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Add data to Cloud Firestore

There are several ways to write data to Cloud Firestore:

  • Set the data of a document within a collection, explicitly specifying a document identifier.
  • Add a new document to a collection. In this case, Cloud Firestore automatically generates the document identifier.
  • Create an empty document with an automatically generated identifier, and assign data to it later.

This guide explains how to use the set, add, or update individual documents in Cloud Firestore. If you want to write data in bulk, see Transactions and Batched Writes.

Before you begin

See Get started with Cloud Firestore to create a Cloud Firestore database.

Initialize Cloud Firestore

Initialize an instance of Cloud Firestore:

Web version 9

import { initializeApp } from "firebase/app";
import { getFirestore } from "firebase/firestore";

// TODO: Replace the following with your app's Firebase project configuration
// See: https://support.google.com/firebase/answer/7015592
const firebaseConfig = {
    FIREBASE_CONFIGURATION
};

// Initialize Firebase
const app = initializeApp(firebaseConfig);


// Initialize Cloud Firestore and get a reference to the service
const db = getFirestore(app);

Replace FIREBASE_CONFIGURATION with your web app's firebaseConfig.

To persist data when the device loses its connection, see the Enable Offline Data documentation.

Web version 8

import firebase from "firebase/app";
import "firebase/firestore";

// TODO: Replace the following with your app's Firebase project configuration
// See: https://support.google.com/firebase/answer/7015592
const firebaseConfig = {
    FIREBASE_CONFIGURATION
};

// Initialize Firebase
firebase.initializeApp(firebaseConfig);


// Initialize Cloud Firestore and get a reference to the service
const db = firebase.firestore();

Replace FIREBASE_CONFIGURATION with your web app's firebaseConfig.

To persist data when the device loses its connection, see the Enable Offline Data documentation.

Swift
Note: This product is not available on watchOS and App Clip targets.
import FirebaseCore
import FirebaseFirestore
FirebaseApp.configure()

let db = Firestore.firestore()
Objective-C
Note: This product is not available on watchOS and App Clip targets.
@import FirebaseCore;
@import FirebaseFirestore;

// Use Firebase library to configure APIs
[FIRApp configure];
  
FIRFirestore *defaultFirestore = [FIRFirestore firestore];

Kotlin+KTX

// Access a Cloud Firestore instance from your Activity
val db = Firebase.firestore

Java

// Access a Cloud Firestore instance from your Activity
FirebaseFirestore db = FirebaseFirestore.getInstance();

Dart

db = FirebaseFirestore.instance;
Java
The Cloud Firestore SDK is initialized in different ways depending on your environment. Below are the most common methods. For a complete reference, see Initialize the Admin SDK.
  • Initialize on Google Cloud
    import com.google.auth.oauth2.GoogleCredentials;
    import com.google.cloud.firestore.Firestore;
    
    import com.google.firebase.FirebaseApp;
    import com.google.firebase.FirebaseOptions;
    
    // Use the application default credentials
    GoogleCredentials credentials = GoogleCredentials.getApplicationDefault();
    FirebaseOptions options = new FirebaseOptions.Builder()
        .setCredentials(credentials)
        .setProjectId(projectId)
        .build();
    FirebaseApp.initializeApp(options);
    
    Firestore db = FirestoreClient.getFirestore();
    
  • Initialize on your own server

    To use the Firebase Admin SDK on your own server, use a service account.

    Go to IAM & admin > Service accounts in the Google Cloud console. Generate a new private key and save the JSON file. Then use the file to initialize the SDK:

    import com.google.auth.oauth2.GoogleCredentials;
    import com.google.cloud.firestore.Firestore;
    
    import com.google.firebase.FirebaseApp;
    import com.google.firebase.FirebaseOptions;
    
    // Use a service account
    InputStream serviceAccount = new FileInputStream("path/to/serviceAccount.json");
    GoogleCredentials credentials = GoogleCredentials.fromStream(serviceAccount);
    FirebaseOptions options = new FirebaseOptions.Builder()
        .setCredentials(credentials)
        .build();
    FirebaseApp.initializeApp(options);
    
    Firestore db = FirestoreClient.getFirestore();
    
  • Python
    The Cloud Firestore SDK is initialized in different ways depending on your environment. Below are the most common methods. For a complete reference, see Initialize the Admin SDK.
  • Initialize on Google Cloud
    import firebase_admin
    from firebase_admin import firestore
    
    # Application Default credentials are automatically created.
    app = firebase_admin.initialize_app()
    db = firestore.client()

    An existing application default credential can also be used to initialize the SDK.

    import firebase_admin
    from firebase_admin import credentials
    from firebase_admin import firestore
    
    # Use the application default credentials.
    cred = credentials.ApplicationDefault()
    
    firebase_admin.initialize_app(cred)
    db = firestore.client()
  • Initialize on your own server

    To use the Firebase Admin SDK on your own server, use a service account.

    Go to IAM & admin > Service accounts in the Google Cloud console. Generate a new private key and save the JSON file. Then use the file to initialize the SDK:

    import firebase_admin
    from firebase_admin import credentials
    from firebase_admin import firestore
    
    # Use a service account.
    cred = credentials.Certificate('path/to/serviceAccount.json')
    
    app = firebase_admin.initialize_app(cred)
    
    db = firestore.client()
  • Python

    The Cloud Firestore SDK is initialized in different ways depending on your environment. Below are the most common methods. For a complete reference, see Initialize the Admin SDK.
  • Initialize on Google Cloud
    import firebase_admin
    from firebase_admin import firestore_async
    
    # Application Default credentials are automatically created.
    app = firebase_admin.initialize_app()
    db = firestore_async.client()

    An existing application default credential can also be used to initialize the SDK.

    import firebase_admin
    from firebase_admin import credentials
    from firebase_admin import firestore_async
    
    # Use the application default credentials.
    cred = credentials.ApplicationDefault()
    
    firebase_admin.initialize_app(cred)
    db = firestore_async.client()
  • Initialize on your own server

    To use the Firebase Admin SDK on your own server, use a service account.

    Go to IAM & admin > Service accounts in the Google Cloud console. Generate a new private key and save the JSON file. Then use the file to initialize the SDK:

    import firebase_admin
    from firebase_admin import credentials
    from firebase_admin import firestore_async
    
    # Use a service account.
    cred = credentials.Certificate('path/to/serviceAccount.json')
    
    app = firebase_admin.initialize_app(cred)
    
    db = firestore_async.client()
  • C++
    // Make sure the call to `Create()` happens some time before you call Firestore::GetInstance().
    App::Create();
    Firestore* db = Firestore::GetInstance();
    Node.js
    The Cloud Firestore SDK is initialized in different ways depending on your environment. Below are the most common methods. For a complete reference, see Initialize the Admin SDK.
    • Initialize on Cloud Functions
      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
      const { getFirestore, Timestamp, FieldValue } = require('firebase-admin/firestore');
      initializeApp();
      
      const db = getFirestore();
      
    • Initialize on Google Cloud
      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
      const { getFirestore, Timestamp, FieldValue } = require('firebase-admin/firestore');
      initializeApp({
        credential: applicationDefault()
      });
      
      const db = getFirestore();
    • Initialize on your own server

      To use the Firebase Admin SDK on your own server (or any other Node.js environment), use a service account. Go to IAM & admin > Service accounts in the Google Cloud console. Generate a new private key and save the JSON file. Then use the file to initialize the SDK:

      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
      const { getFirestore, Timestamp, FieldValue } = require('firebase-admin/firestore');
      const serviceAccount = require('./path/to/serviceAccountKey.json');
      
      initializeApp({
        credential: cert(serviceAccount)
      });
      
      const db = getFirestore();
      
    Go
    The Cloud Firestore SDK is initialized in different ways depending on your environment. Below are the most common methods. For a complete reference, see Initialize the Admin SDK.
  • Initialize on Google Cloud
    import (
      "log"
    
      firebase "firebase.google.com/go"
      "google.golang.org/api/option"
    )
    
    // Use the application default credentials
    ctx := context.Background()
    conf := &firebase.Config{ProjectID: projectID}
    app, err := firebase.NewApp(ctx, conf)
    if err != nil {
      log.Fatalln(err)
    }
    
    client, err := app.Firestore(ctx)
    if err != nil {
      log.Fatalln(err)
    }
    defer client.Close()
    
  • Initialize on your own server

    To use the Firebase Admin SDK on your own server, use a service account.

    Go to IAM & admin > Service accounts in the Google Cloud console. Generate a new private key and save the JSON file. Then use the file to initialize the SDK:

    import (
      "log"
    
      firebase "firebase.google.com/go"
      "google.golang.org/api/option"
    )
    
    // Use a service account
    ctx := context.Background()
    sa := option.WithCredentialsFile("path/to/serviceAccount.json")
    app, err := firebase.NewApp(ctx, nil, sa)
    if err != nil {
      log.Fatalln(err)
    }
    
    client, err := app.Firestore(ctx)
    if err != nil {
      log.Fatalln(err)
    }
    defer client.Close()
    
  • PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    use Google\Cloud\Firestore\FirestoreClient;
    
    /**
     * Initialize Cloud Firestore with default project ID.
     */
    function setup_client_create(string $projectId = null)
    {
        // Create the Cloud Firestore client
        if (empty($projectId)) {
            // The `projectId` parameter is optional and represents which project the
            // client will act on behalf of. If not supplied, the client falls back to
            // the default project inferred from the environment.
            $db = new FirestoreClient();
            printf('Created Cloud Firestore client with default project ID.' . PHP_EOL);
        } else {
            $db = new FirestoreClient([
                'projectId' => $projectId,
            ]);
            printf('Created Cloud Firestore client with project ID: %s' . PHP_EOL, $projectId);
        }
    }
    Unity
    using Firebase.Firestore;
    using Firebase.Extensions;
    FirebaseFirestore db = FirebaseFirestore.DefaultInstance;
    C#

    C#

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    FirestoreDb db = FirestoreDb.Create(project);
    Console.WriteLine("Created Cloud Firestore client with project ID: {0}", project);
    Ruby
    require "google/cloud/firestore"
    
    # The `project_id` parameter is optional and represents which project the
    # client will act on behalf of. If not supplied, the client falls back to the
    # default project inferred from the environment.
    firestore = Google::Cloud::Firestore.new project_id: project_id
    
    puts "Created Cloud Firestore client with given project ID."

    Set a document

    To create or overwrite a single document, use the following language-specific set() methods:

    Web version 9

    Use the setDoc() method:

    import { doc, setDoc } from "firebase/firestore"; 
    
    // Add a new document in collection "cities"
    await setDoc(doc(db, "cities", "LA"), {
      name: "Los Angeles",
      state: "CA",
      country: "USA"
    });

    Web version 8

    Use the set() method:

    // Add a new document in collection "cities"
    db.collection("cities").doc("LA").set({
        name: "Los Angeles",
        state: "CA",
        country: "USA"
    })
    .then(() => {
        console.log("Document successfully written!");
    })
    .catch((error) => {
        console.error("Error writing document: ", error);
    });
    Swift

    Use the setData() method:

    Note: This product is not available on watchOS and App Clip targets.
    // Add a new document in collection "cities"
    db.collection("cities").document("LA").setData([
        "name": "Los Angeles",
        "state": "CA",
        "country": "USA"
    ]) { err in
        if let err = err {
            print("Error writing document: \(err)")
        } else {
            print("Document successfully written!")
        }
    }
    Objective-C

    Use the setData: method:

    Note: This product is not available on watchOS and App Clip targets.
    // Add a new document in collection "cities"
    [[[self.db collectionWithPath:@"cities"] documentWithPath:@"LA"] setData:@{
      @"name": @"Los Angeles",
      @"state": @"CA",
      @"country": @"USA"
    } completion:^(NSError * _Nullable error) {
      if (error != nil) {
        NSLog(@"Error writing document: %@", error);
      } else {
        NSLog(@"Document successfully written!");
      }
    }];

    Kotlin+KTX

    Use the set() method:

    val city = hashMapOf(
            "name" to "Los Angeles",
            "state" to "CA",
            "country" to "USA"
    )
    
    db.collection("cities").document("LA")
            .set(city)
            .addOnSuccessListener { Log.d(TAG, "DocumentSnapshot successfully written!") }
            .addOnFailureListener { e -> Log.w(TAG, "Error writing document", e) }

    Java

    Use the set() method:

    Map<String, Object> city = new HashMap<>();
    city.put("name", "Los Angeles");
    city.put("state", "CA");
    city.put("country", "USA");
    
    db.collection("cities").document("LA")
            .set(city)
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Log.d(TAG, "DocumentSnapshot successfully written!");
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.w(TAG, "Error writing document", e);
                }
            });
    

    Dart

    Use the set() method:

    final city = <String, String>{
      "name": "Los Angeles",
      "state": "CA",
      "country": "USA"
    };
    
    db
        .collection("cities")
        .doc("LA")
        .set(city)
        .onError((e, _) => print("Error writing document: $e"));
    Java

    Use the set() method:

    // Create a Map to store the data we want to set
    Map<String, Object> docData = new HashMap<>();
    docData.put("name", "Los Angeles");
    docData.put("state", "CA");
    docData.put("country", "USA");
    docData.put("regions", Arrays.asList("west_coast", "socal"));
    // Add a new document (asynchronously) in collection "cities" with id "LA"
    ApiFuture<WriteResult> future = db.collection("cities").document("LA").set(docData);
    // ...
    // future.get() blocks on response
    System.out.println("Update time : " + future.get().getUpdateTime());
    Python

    Use the set() method:

    data = {
        u'name': u'Los Angeles',
        u'state': u'CA',
        u'country': u'USA'
    }
    
    # Add a new doc in collection 'cities' with ID 'LA'
    db.collection(u'cities').document(u'LA').set(data)

    Python

    Use the set() method:

    data = {"name": "Los Angeles", "state": "CA", "country": "USA"}
    
    # Add a new doc in collection 'cities' with ID 'LA'
    await db.collection("cities").document("LA").set(data)
    C++

    Use the Set() method:

    // Add a new document in collection 'cities'
    db->Collection("cities")
        .Document("LA")
        .Set({{"name", FieldValue::String("Los Angeles")},
              {"state", FieldValue::String("CA")},
              {"country", FieldValue::String("USA")}})
        .OnCompletion([](const Future<void>& future) {
          if (future.error() == Error::kErrorOk) {
            std::cout << "DocumentSnapshot successfully written!" << std::endl;
          } else {
            std::cout << "Error writing document: " << future.error_message()
                      << std::endl;
          }
        });
    Node.js

    Use the set() method:

    const data = {
      name: 'Los Angeles',
      state: 'CA',
      country: 'USA'
    };
    
    // Add a new document in collection "cities" with ID 'LA'
    const res = await db.collection('cities').doc('LA').set(data);
    Go

    Use the Set() method:

    _, err := client.Collection("cities").Doc("LA").Set(ctx, map[string]interface{}{
    	"name":    "Los Angeles",
    	"state":   "CA",
    	"country": "USA",
    })
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    Use the set() method:

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $data = [
        'name' => 'Los Angeles',
        'state' => 'CA',
        'country' => 'USA'
    ];
    $db->collection('samples/php/cities')->document('LA')->set($data);
    Unity

    Use the SetAsync() method:

    DocumentReference docRef = db.Collection("cities").Document("LA");
    Dictionary<string, object> city = new Dictionary<string, object>
    {
    	{ "Name", "Los Angeles" },
    	{ "State", "CA" },
    	{ "Country", "USA" }
    };
    docRef.SetAsync(city).ContinueWithOnMainThread(task => {
    	Debug.Log("Added data to the LA document in the cities collection.");
    });
    C#

    Use the SetAsync() method:

    DocumentReference docRef = db.Collection("cities").Document("LA");
    Dictionary<string, object> city = new Dictionary<string, object>
    {
        { "name", "Los Angeles" },
        { "state", "CA" },
        { "country", "USA" }
    };
    await docRef.SetAsync(city);
    Ruby

    Use the set() method:

    city_ref = firestore.doc "#{collection_path}/LA"
    
    data = {
      name:    "Los Angeles",
      state:   "CA",
      country: "USA"
    }
    
    city_ref.set data

    If the document does not exist, it will be created. If the document does exist, its contents will be overwritten with the newly provided data, unless you specify that the data should be merged into the existing document, as follows:

    Web version 9

    import { doc, setDoc } from "firebase/firestore"; 
    
    const cityRef = doc(db, 'cities', 'BJ');
    setDoc(cityRef, { capital: true }, { merge: true });

    Web version 8

    var cityRef = db.collection('cities').doc('BJ');
    
    var setWithMerge = cityRef.set({
        capital: true
    }, { merge: true });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    // Update one field, creating the document if it does not exist.
    db.collection("cities").document("BJ").setData([ "capital": true ], merge: true)
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    // Write to the document reference, merging data with existing
    // if the document already exists
    [[[self.db collectionWithPath:@"cities"] documentWithPath:@"BJ"]
         setData:@{ @"capital": @YES }
         merge:YES
         completion:^(NSError * _Nullable error) {
           // ...
         }];

    Kotlin+KTX

    // Update one field, creating the document if it does not already exist.
    val data = hashMapOf("capital" to true)
    
    db.collection("cities").document("BJ")
            .set(data, SetOptions.merge())
    

    Java

    // Update one field, creating the document if it does not already exist.
    Map<String, Object> data = new HashMap<>();
    data.put("capital", true);
    
    db.collection("cities").document("BJ")
            .set(data, SetOptions.merge());
    

    Dart

    // Update one field, creating the document if it does not already exist.
    final data = {"capital": true};
    
    db.collection("cities").doc("BJ").set(data, SetOptions(merge: true));
    Java
    // asynchronously update doc, create the document if missing
    Map<String, Object> update = new HashMap<>();
    update.put("capital", true);
    
    ApiFuture<WriteResult> writeResult =
        db.collection("cities").document("BJ").set(update, SetOptions.merge());
    // ...
    System.out.println("Update time : " + writeResult.get().getUpdateTime());
    Python
    city_ref = db.collection(u'cities').document(u'BJ')
    
    city_ref.set({
        u'capital': True
    }, merge=True)

    Python

    city_ref = db.collection("cities").document("BJ")
    
    await city_ref.set({"capital": True}, merge=True)
    C++
    db->Collection("cities").Document("BJ").Set(
        {{"capital", FieldValue::Boolean(true)}}, SetOptions::Merge());
    Node.js
    const cityRef = db.collection('cities').doc('BJ');
    
    const res = await cityRef.set({
      capital: true
    }, { merge: true });
    Go
    _, err := client.Collection("cities").Doc("BJ").Set(ctx, map[string]interface{}{
    	"capital": true,
    }, firestore.MergeAll)
    
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $cityRef = $db->collection('samples/php/cities')->document('BJ');
    $cityRef->set([
        'capital' => true
    ], ['merge' => true]);
    Unity
    DocumentReference docRef = db.Collection("cities").Document("LA");
    Dictionary<string, object> update = new Dictionary<string, object>
    {
    	{ "capital", false }
    };
    docRef.SetAsync(update, SetOptions.MergeAll);
    C#
    DocumentReference docRef = db.Collection("cities").Document("LA");
    Dictionary<string, object> update = new Dictionary<string, object>
    {
        { "capital", false }
    };
    await docRef.SetAsync(update, SetOptions.MergeAll);
    Ruby
    city_ref = firestore.doc "#{collection_path}/LA"
    city_ref.set({ capital: false }, merge: true)

    If you're not sure whether the document exists, pass the option to merge the new data with any existing document to avoid overwriting entire documents. For documents containing maps, note that specifying a set with a field containing an empty map will overwrite the target document's map field.

    Data types

    Cloud Firestore lets you write a variety of data types inside a document, including strings, booleans, numbers, dates, null, and nested arrays and objects. Cloud Firestore always stores numbers as doubles, regardless of what type of number you use in your code.

    Web version 9

    import { doc, setDoc, Timestamp } from "firebase/firestore"; 
    
    const docData = {
        stringExample: "Hello world!",
        booleanExample: true,
        numberExample: 3.14159265,
        dateExample: Timestamp.fromDate(new Date("December 10, 1815")),
        arrayExample: [5, true, "hello"],
        nullExample: null,
        objectExample: {
            a: 5,
            b: {
                nested: "foo"
            }
        }
    };
    await setDoc(doc(db, "data", "one"), docData);

    Web version 8

    var docData = {
        stringExample: "Hello world!",
        booleanExample: true,
        numberExample: 3.14159265,
        dateExample: firebase.firestore.Timestamp.fromDate(new Date("December 10, 1815")),
        arrayExample: [5, true, "hello"],
        nullExample: null,
        objectExample: {
            a: 5,
            b: {
                nested: "foo"
            }
        }
    };
    db.collection("data").doc("one").set(docData).then(() => {
        console.log("Document successfully written!");
    });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    let docData: [String: Any] = [
        "stringExample": "Hello world!",
        "booleanExample": true,
        "numberExample": 3.14159265,
        "dateExample": Timestamp(date: Date()),
        "arrayExample": [5, true, "hello"],
        "nullExample": NSNull(),
        "objectExample": [
            "a": 5,
            "b": [
                "nested": "foo"
            ]
        ]
    ]
    db.collection("data").document("one").setData(docData) { err in
        if let err = err {
            print("Error writing document: \(err)")
        } else {
            print("Document successfully written!")
        }
    }
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    NSDictionary *docData = @{
      @"stringExample": @"Hello world!",
      @"booleanExample": @YES,
      @"numberExample": @3.14,
      @"dateExample": [FIRTimestamp timestampWithDate:[NSDate date]],
      @"arrayExample": @[@5, @YES, @"hello"],
      @"nullExample": [NSNull null],
      @"objectExample": @{
        @"a": @5,
        @"b": @{
          @"nested": @"foo"
        }
      }
    };
    
    [[[self.db collectionWithPath:@"data"] documentWithPath:@"one"] setData:docData
        completion:^(NSError * _Nullable error) {
          if (error != nil) {
            NSLog(@"Error writing document: %@", error);
          } else {
            NSLog(@"Document successfully written!");
          }
        }];

    Kotlin+KTX

    val docData = hashMapOf(
            "stringExample" to "Hello world!",
            "booleanExample" to true,
            "numberExample" to 3.14159265,
            "dateExample" to Timestamp(Date()),
            "listExample" to arrayListOf(1, 2, 3),
            "nullExample" to null
    )
    
    val nestedData = hashMapOf(
            "a" to 5,
            "b" to true
    )
    
    docData["objectExample"] = nestedData
    
    db.collection("data").document("one")
            .set(docData)
            .addOnSuccessListener { Log.d(TAG, "DocumentSnapshot successfully written!") }
            .addOnFailureListener { e -> Log.w(TAG, "Error writing document", e) }
    

    Java

    Map<String, Object> docData = new HashMap<>();
    docData.put("stringExample", "Hello world!");
    docData.put("booleanExample", true);
    docData.put("numberExample", 3.14159265);
    docData.put("dateExample", new Timestamp(new Date()));
    docData.put("listExample", Arrays.asList(1, 2, 3));
    docData.put("nullExample", null);
    
    Map<String, Object> nestedData = new HashMap<>();
    nestedData.put("a", 5);
    nestedData.put("b", true);
    
    docData.put("objectExample", nestedData);
    
    db.collection("data").document("one")
            .set(docData)
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Log.d(TAG, "DocumentSnapshot successfully written!");
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.w(TAG, "Error writing document", e);
                }
            });
    

    Dart

    final docData = {
      "stringExample": "Hello world!",
      "booleanExample": true,
      "numberExample": 3.14159265,
      "dateExample": Timestamp.now(),
      "listExample": [1, 2, 3],
      "nullExample": null
    };
    
    final nestedData = {
      "a": 5,
      "b": true,
    };
    
    docData["objectExample"] = nestedData;
    
    db
        .collection("data")
        .doc("one")
        .set(docData)
        .onError((e, _) => print("Error writing document: $e"));
    Java
    Map<String, Object> docData = new HashMap<>();
    docData.put("stringExample", "Hello, World");
    docData.put("booleanExample", false);
    docData.put("numberExample", 3.14159265);
    docData.put("nullExample", null);
    
    ArrayList<Object> arrayExample = new ArrayList<>();
    Collections.addAll(arrayExample, 5L, true, "hello");
    docData.put("arrayExample", arrayExample);
    
    Map<String, Object> objectExample = new HashMap<>();
    objectExample.put("a", 5L);
    objectExample.put("b", true);
    
    docData.put("objectExample", objectExample);
    
    ApiFuture<WriteResult> future = db.collection("data").document("one").set(docData);
    System.out.println("Update time : " + future.get().getUpdateTime());
    Python
    data = {
        u'stringExample': u'Hello, World!',
        u'booleanExample': True,
        u'numberExample': 3.14159265,
        u'dateExample': datetime.datetime.now(tz=datetime.timezone.utc),
        u'arrayExample': [5, True, u'hello'],
        u'nullExample': None,
        u'objectExample': {
            u'a': 5,
            u'b': True
        }
    }
    
    db.collection(u'data').document(u'one').set(data)

    Python

    data = {
        "stringExample": "Hello, World!",
        "booleanExample": True,
        "numberExample": 3.14159265,
        "dateExample": datetime.datetime.now(tz=datetime.timezone.utc),
        "arrayExample": [5, True, "hello"],
        "nullExample": None,
        "objectExample": {"a": 5, "b": True},
    }
    
    await db.collection("data").document("one").set(data)
    C++
    MapFieldValue doc_data{
        {"stringExample", FieldValue::String("Hello world!")},
        {"booleanExample", FieldValue::Boolean(true)},
        {"numberExample", FieldValue::Double(3.14159265)},
        {"dateExample", FieldValue::Timestamp(Timestamp::Now())},
        {"arrayExample", FieldValue::Array({FieldValue::Integer(1),
                                            FieldValue::Integer(2),
                                            FieldValue::Integer(3)})},
        {"nullExample", FieldValue::Null()},
        {"objectExample",
         FieldValue::Map(
             {{"a", FieldValue::Integer(5)},
              {"b", FieldValue::Map(
                        {{"nested", FieldValue::String("foo")}})}})},
    };
    
    db->Collection("data").Document("one").Set(doc_data).OnCompletion(
        [](const Future<void>& future) {
          if (future.error() == Error::kErrorOk) {
            std::cout << "DocumentSnapshot successfully written!" << std::endl;
          } else {
            std::cout << "Error writing document: " << future.error_message()
                      << std::endl;
          }
        });
    Node.js
    const data = {
      stringExample: 'Hello, World!',
      booleanExample: true,
      numberExample: 3.14159265,
      dateExample: Timestamp.fromDate(new Date('December 10, 1815')),
      arrayExample: [5, true, 'hello'],
      nullExample: null,
      objectExample: {
        a: 5,
        b: true
      }
    };
    
    const res = await db.collection('data').doc('one').set(data);
    Go
    doc := make(map[string]interface{})
    doc["stringExample"] = "Hello world!"
    doc["booleanExample"] = true
    doc["numberExample"] = 3.14159265
    doc["dateExample"] = time.Now()
    doc["arrayExample"] = []interface{}{5, true, "hello"}
    doc["nullExample"] = nil
    doc["objectExample"] = map[string]interface{}{
    	"a": 5,
    	"b": true,
    }
    
    _, err := client.Collection("data").Doc("one").Set(ctx, doc)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $data = [
        'stringExample' => 'Hello World',
        'booleanExample' => true,
        'numberExample' => 3.14159265,
        'dateExample' => new Timestamp(new DateTime()),
        'arrayExample' => array(5, true, 'hello'),
        'nullExample' => null,
        'objectExample' => ['a' => 5, 'b' => true],
        'documentReferenceExample' => $db->collection('samples/php/data')->document('two'),
    ];
    $db->collection('samples/php/data')->document('one')->set($data);
    printf('Set multiple data-type data for the one document in the data collection.' . PHP_EOL);
    Unity
    DocumentReference docRef = db.Collection("data").Document("one");
    Dictionary<string, object> docData = new Dictionary<string, object>
    {
    	{ "stringExample", "Hello World" },
    	{ "booleanExample", false },
    	{ "numberExample", 3.14159265 },
    	{ "nullExample", null },
    	{ "arrayExample", new List<object>() { 5, true, "Hello" } },
    	{ "objectExample", new Dictionary<string, object>
    		{
    			{ "a", 5 },
    			{ "b", true },
    		}
    	},
    };
    
    docRef.SetAsync(docData);
    C#
    DocumentReference docRef = db.Collection("data").Document("one");
    Dictionary<string, object> docData = new Dictionary<string, object>
    {
        { "stringExample", "Hello World" },
        { "booleanExample", false },
        { "numberExample", 3.14159265 },
        { "nullExample", null },
    };
    
    ArrayList arrayExample = new ArrayList();
    arrayExample.Add(5);
    arrayExample.Add(true);
    arrayExample.Add("Hello");
    docData.Add("arrayExample", arrayExample);
    
    Dictionary<string, object> objectExample = new Dictionary<string, object>
    {
        { "a", 5 },
        { "b", true },
    };
    docData.Add("objectExample", objectExample);
    
    await docRef.SetAsync(docData);
    Ruby
    doc_ref = firestore.doc "#{collection_path}/one"
    
    data = {
      stringExample:  "Hello, World!",
      booleanExample: true,
      numberExample:  3.14159265,
      dateExample:    DateTime.now,
      arrayExample:   [5, true, "hello"],
      nullExample:    nil,
      objectExample:  {
        a: 5,
        b: true
      }
    }
    
    doc_ref.set data

    Custom objects

    Using Map or Dictionary objects to represent your documents is often not very convenient, so Cloud Firestore supports writing documents with custom classes. Cloud Firestore converts the objects to supported data types.

    Using custom classes, you could rewrite the initial example as shown:

    Web version 9

    class City {
        constructor (name, state, country ) {
            this.name = name;
            this.state = state;
            this.country = country;
        }
        toString() {
            return this.name + ', ' + this.state + ', ' + this.country;
        }
    }
    
    // Firestore data converter
    const cityConverter = {
        toFirestore: (city) => {
            return {
                name: city.name,
                state: city.state,
                country: city.country
                };
        },
        fromFirestore: (snapshot, options) => {
            const data = snapshot.data(options);
            return new City(data.name, data.state, data.country);
        }
    };

    Web version 8

    class City {
        constructor (name, state, country ) {
            this.name = name;
            this.state = state;
            this.country = country;
        }
        toString() {
            return this.name + ', ' + this.state + ', ' + this.country;
        }
    }
    
    // Firestore data converter
    var cityConverter = {
        toFirestore: function(city) {
            return {
                name: city.name,
                state: city.state,
                country: city.country
                };
        },
        fromFirestore: function(snapshot, options){
            const data = snapshot.data(options);
            return new City(data.name, data.state, data.country);
        }
    };
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    public struct City: Codable {
    
        let name: String
        let state: String?
        let country: String?
        let isCapital: Bool?
        let population: Int64?
    
        enum CodingKeys: String, CodingKey {
            case name
            case state
            case country
            case isCapital = "capital"
            case population
        }
    
    }
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    // This isn't supported in Objective-C.
      

    Kotlin+KTX

    data class City(
        val name: String? = null,
        val state: String? = null,
        val country: String? = null,
        @field:JvmField // use this annotation if your Boolean field is prefixed with 'is'
        val isCapital: Boolean? = null,
        val population: Long? = null,
        val regions: List<String>? = null
    )
    

    Java

    Each custom class must have a public constructor that takes no arguments. In addition, the class must include a public getter for each property.

    public class City {
    
    
        private String name;
        private String state;
        private String country;
        private boolean capital;
        private long population;
        private List<String> regions;
    
        public City() {}
    
        public City(String name, String state, String country, boolean capital, long population, List<String> regions) {
            // ...
        }
    
        public String getName() {
            return name;
        }
    
        public String getState() {
            return state;
        }
    
        public String getCountry() {
            return country;
        }
    
        public boolean isCapital() {
            return capital;
        }
    
        public long getPopulation() {
            return population;
        }
    
        public List<String> getRegions() {
            return regions;
        }
    
    }
    

    Dart

    class City {
      final String? name;
      final String? state;
      final String? country;
      final bool? capital;
      final int? population;
      final List<String>? regions;
    
      City({
        this.name,
        this.state,
        this.country,
        this.capital,
        this.population,
        this.regions,
      });
    
      factory City.fromFirestore(
        DocumentSnapshot<Map<String, dynamic>> snapshot,
        SnapshotOptions? options,
      ) {
        final data = snapshot.data();
        return City(
          name: data?['name'],
          state: data?['state'],
          country: data?['country'],
          capital: data?['capital'],
          population: data?['population'],
          regions:
              data?['regions'] is Iterable ? List.from(data?['regions']) : null,
        );
      }
    
      Map<String, dynamic> toFirestore() {
        return {
          if (name != null) "name": name,
          if (state != null) "state": state,
          if (country != null) "country": country,
          if (capital != null) "capital": capital,
          if (population != null) "population": population,
          if (regions != null) "regions": regions,
        };
      }
    }
    Java
    public City() {
      // Must have a public no-argument constructor
    }
    
    // Initialize all fields of a city
    public City(
        String name,
        String state,
        String country,
        Boolean capital,
        Long population,
        List<String> regions) {
      this.name = name;
      this.state = state;
      this.country = country;
      this.capital = capital;
      this.population = population;
      this.regions = regions;
    }
    Python
    class City(object):
        def __init__(self, name, state, country, capital=False, population=0,
                     regions=[]):
            self.name = name
            self.state = state
            self.country = country
            self.capital = capital
            self.population = population
            self.regions = regions
    
        @staticmethod
        def from_dict(source):
            # ...
    
        def to_dict(self):
            # ...
    
        def __repr__(self):
            return (
                f'City(\
                    name={self.name}, \
                    country={self.country}, \
                    population={self.population}, \
                    capital={self.capital}, \
                    regions={self.regions}\
                )'
            )

    Python

    class City(object):
        def __init__(self, name, state, country, capital=False, population=0, regions=[]):
            self.name = name
            self.state = state
            self.country = country
            self.capital = capital
            self.population = population
            self.regions = regions
    
        @staticmethod
        def from_dict(source):
            # ...
    
        def to_dict(self):
            # ...
    
        def __repr__(self):
            return f"City(\
                    name={self.name}, \
                    country={self.country}, \
                    population={self.population}, \
                    capital={self.capital}, \
                    regions={self.regions}\
                )"
    
    C++
    // This is not yet supported.
    
    Node.js
    // Node.js uses JavaScript objects
    
    Go
    
    // City represents a city.
    type City struct {
    	Name       string   `firestore:"name,omitempty"`
    	State      string   `firestore:"state,omitempty"`
    	Country    string   `firestore:"country,omitempty"`
    	Capital    bool     `firestore:"capital,omitempty"`
    	Population int64    `firestore:"population,omitempty"`
    	Regions    []string `firestore:"regions,omitempty"`
    }
    
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    class City
    {
        /* var string */
        public $name;
        /* var string */
        public $state;
        /* var string */
        public $country;
        /* var bool */
        public $capital;
        /* var int */
        public $population;
        /* var array */
        public $regions;
    
        public function __construct(
            string $name,
            string $state,
            string $country,
            bool $capital = false,
            int $population = 0,
            array $regions = []
        ) {
            $this->name = $name;
            $this->state = $state;
            $this->country = $country;
            $this->capital = $capital;
            $this->population = $population;
            $this->regions = $regions;
        }
    
        public static function fromArray(array $source): City
        {
            // implementation of fromArray is excluded for brevity
            # ...
        }
    
        public function toArray(): array
        {
            // implementation of toArray is excluded for brevity
            # ...
        }
    
        public function __toString()
        {
            // implementation of __toString is excluded for brevity
            # ...
        }
    }
    
    Unity
    [FirestoreData]
    public class City
    {
    	[FirestoreProperty]
    	public string Name { get; set; }
    
    	[FirestoreProperty]
    	public string State { get; set; }
    
    	[FirestoreProperty]
    	public string Country { get; set; }
    
    	[FirestoreProperty]
    	public bool Capital { get; set; }
    
    	[FirestoreProperty]
    	public long Population { get; set; }
    }
    C#
    [FirestoreData]
    public class City
    {
        [FirestoreProperty]
        public string Name { get; set; }
    
        [FirestoreProperty]
        public string State { get; set; }
    
        [FirestoreProperty]
        public string Country { get; set; }
    
        [FirestoreProperty]
        public bool Capital { get; set; }
    
        [FirestoreProperty]
        public long Population { get; set; }
    }
    Ruby
    // This isn't supported in Ruby
    

    Web version 9

    import { doc, setDoc } from "firebase/firestore"; 
    
    // Set with cityConverter
    const ref = doc(db, "cities", "LA").withConverter(cityConverter);
    await setDoc(ref, new City("Los Angeles", "CA", "USA"));

    Web version 8

    // Set with cityConverter
    db.collection("cities").doc("LA")
      .withConverter(cityConverter)
      .set(new City("Los Angeles", "CA", "USA"));
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    let city = City(name: "Los Angeles",
                    state: "CA",
                    country: "USA",
                    isCapital: false,
                    population: 5000000)
    
    do {
        try db.collection("cities").document("LA").setData(from: city)
    } catch let error {
        print("Error writing city to Firestore: \(error)")
    }
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    // This isn't supported in Objective-C.
      

    Kotlin+KTX

    val city = City("Los Angeles", "CA", "USA",
            false, 5000000L, listOf("west_coast", "socal"))
    db.collection("cities").document("LA").set(city)
    

    Java

    City city = new City("Los Angeles", "CA", "USA",
            false, 5000000L, Arrays.asList("west_coast", "sorcal"));
    db.collection("cities").document("LA").set(city);
    

    Dart

    final city = City(
      name: "Los Angeles",
      state: "CA",
      country: "USA",
      capital: false,
      population: 5000000,
      regions: ["west_coast", "socal"],
    );
    final docRef = db
        .collection("cities")
        .withConverter(
          fromFirestore: City.fromFirestore,
          toFirestore: (City city, options) => city.toFirestore(),
        )
        .doc("LA");
    await docRef.set(city);
    Java
    City city =
        new City("Los Angeles", "CA", "USA", false, 3900000L, Arrays.asList("west_coast", "socal"));
    ApiFuture<WriteResult> future = db.collection("cities").document("LA").set(city);
    // block on response if required
    System.out.println("Update time : " + future.get().getUpdateTime());
    Python
    city = City(name=u'Los Angeles', state=u'CA', country=u'USA')
    db.collection(u'cities').document(u'LA').set(city.to_dict())

    Python

    city = City(name="Los Angeles", state="CA", country="USA")
    await db.collection("cities").document("LA").set(city.to_dict())
    C++
    // This is not yet supported.
    
    Node.js
    // Node.js uses JavaScript objects
    
    Go
    city := City{
    	Name:    "Los Angeles",
    	Country: "USA",
    }
    _, err := client.Collection("cities").Doc("LA").Set(ctx, city)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP
    // This isn't supported in PHP.
    
    Unity
    DocumentReference docRef = db.Collection("cities").Document("LA");
    City city = new City
    {
    	Name = "Los Angeles",
    	State = "CA",
    	Country = "USA",
    	Capital = false,
    	Population = 3900000L
    };
    docRef.SetAsync(city);
    C#
    DocumentReference docRef = db.Collection("cities").Document("LA");
    City city = new City
    {
        Name = "Los Angeles",
        State = "CA",
        Country = "USA",
        Capital = false,
        Population = 3900000L
    };
    await docRef.SetAsync(city);
    Ruby
    // This isn't supported in Ruby.
    

    Add a document

    When you use set() to create a document, you must specify an ID for the document to create. For example:

    Web version 9

    import { doc, setDoc } from "firebase/firestore"; 
    
    await setDoc(doc(db, "cities", "new-city-id"), data);

    Web version 8

    db.collection("cities").doc("new-city-id").set(data);
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    db.collection("cities").document("new-city-id").setData(data)
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    [[[self.db collectionWithPath:@"cities"] documentWithPath:@"new-city-id"]
        setData:data];

    Kotlin+KTX

    db.collection("cities").document("new-city-id").set(data)
    

    Java

    db.collection("cities").document("new-city-id").set(data);
    

    Dart

    db.collection("cities").doc("new-city-id").set({"name": "Chicago"});
    Java
    db.collection("cities").document("new-city-id").set(data);
    Python
    db.collection(u'cities').document(u'new-city-id').set(data)

    Python

    await db.collection("cities").document("new-city-id").set(data)
    C++
    db->Collection("cities").Document("SF").Set({/*some data*/});
    Node.js
    await db.collection('cities').doc('new-city-id').set(data);
    Go
    _, err := client.Collection("cities").Doc("new-city-id").Set(ctx, data)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $db->collection('samples/php/cities')->document('new-city-id')->set($data);
    Unity
    db.Collection("cities").Document("new-city-id").SetAsync(city);
    C#
    await db.Collection("cities").Document("new-city-id").SetAsync(city);
    Ruby
    city_ref = firestore.doc "#{collection_path}/new-city-id"
    city_ref.set data

    But sometimes there isn't a meaningful ID for the document, and it's more convenient to let Cloud Firestore auto-generate an ID for you. You can do this by calling the following language-specific add() methods:

    Web version 9

    Use the addDoc() method:

    import { collection, addDoc } from "firebase/firestore"; 
    
    // Add a new document with a generated id.
    const docRef = await addDoc(collection(db, "cities"), {
      name: "Tokyo",
      country: "Japan"
    });
    console.log("Document written with ID: ", docRef.id);

    Web version 8

    Use the add() method:

    // Add a new document with a generated id.
    db.collection("cities").add({
        name: "Tokyo",
        country: "Japan"
    })
    .then((docRef) => {
        console.log("Document written with ID: ", docRef.id);
    })
    .catch((error) => {
        console.error("Error adding document: ", error);
    });
    Swift

    Use the addDocument() method:

    Note: This product is not available on watchOS and App Clip targets.
    // Add a new document with a generated id.
    var ref: DocumentReference? = nil
    ref = db.collection("cities").addDocument(data: [
        "name": "Tokyo",
        "country": "Japan"
    ]) { err in
        if let err = err {
            print("Error adding document: \(err)")
        } else {
            print("Document added with ID: \(ref!.documentID)")
        }
    }
    Objective-C

    Use the addDocumentWithData: method:

    Note: This product is not available on watchOS and App Clip targets.
    // Add a new document with a generated id.
    __block FIRDocumentReference *ref =
        [[self.db collectionWithPath:@"cities"] addDocumentWithData:@{
          @"name": @"Tokyo",
          @"country": @"Japan"
        } completion:^(NSError * _Nullable error) {
          if (error != nil) {
            NSLog(@"Error adding document: %@", error);
          } else {
            NSLog(@"Document added with ID: %@", ref.documentID);
          }
        }];

    Kotlin+KTX

    Use the add() method:

    // Add a new document with a generated id.
    val data = hashMapOf(
            "name" to "Tokyo",
            "country" to "Japan"
    )
    
    db.collection("cities")
        .add(data)
        .addOnSuccessListener { documentReference ->
            Log.d(TAG, "DocumentSnapshot written with ID: ${documentReference.id}")
        }
        .addOnFailureListener { e ->
            Log.w(TAG, "Error adding document", e)
        }
    

    Java

    Use the add() method:

    // Add a new document with a generated id.
    Map<String, Object> data = new HashMap<>();
    data.put("name", "Tokyo");
    data.put("country", "Japan");
    
    db.collection("cities")
            .add(data)
            .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                @Override
                public void onSuccess(DocumentReference documentReference) {
                    Log.d(TAG, "DocumentSnapshot written with ID: " + documentReference.getId());
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.w(TAG, "Error adding document", e);
                }
            });
    

    Dart

    Use the add() method:

    // Add a new document with a generated id.
    final data = {"name": "Tokyo", "country": "Japan"};
    
    db.collection("cities").add(data).then((documentSnapshot) =>
        print("Added Data with ID: ${documentSnapshot.id}"));
    Java

    Use the add() method:

    // Add document data with auto-generated id.
    Map<String, Object> data = new HashMap<>();
    data.put("name", "Tokyo");
    data.put("country", "Japan");
    ApiFuture<DocumentReference> addedDocRef = db.collection("cities").add(data);
    System.out.println("Added document with ID: " + addedDocRef.get().getId());
    Python

    Use the add() method:

    city = {
        u'name': u'Tokyo',
        u'country': u'Japan'
    }
    update_time, city_ref = db.collection(u'cities').add(city)
    print(f'Added document with id {city_ref.id}')

    Python

    Use the add() method:

    city = City(name="Tokyo", state=None, country="Japan")
    await db.collection("cities").add(city.to_dict())
    C++

    Use the Add() method:

    db->Collection("cities").Add({/*some data*/});
    Node.js

    Use the add() method:

    // Add a new document with a generated id.
    const res = await db.collection('cities').add({
      name: 'Tokyo',
      country: 'Japan'
    });
    
    console.log('Added document with ID: ', res.id);
    Go

    Use the Add() method:

    _, _, err := client.Collection("cities").Add(ctx, map[string]interface{}{
    	"name":    "Tokyo",
    	"country": "Japan",
    })
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    Use the add() method:

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $data = [
        'name' => 'Tokyo',
        'country' => 'Japan'
    ];
    $addedDocRef = $db->collection('samples/php/cities')->add($data);
    printf('Added document with ID: %s' . PHP_EOL, $addedDocRef->id());
    Unity

    Use the AddAsync() method:

    Dictionary<string, object> city = new Dictionary<string, object>
    {
    	{ "Name", "Tokyo" },
    	{ "Country", "Japan" }
    };
    db.Collection("cities").AddAsync(city).ContinueWithOnMainThread(task => {
    	DocumentReference addedDocRef = task.Result;
    	Debug.Log(String.Format("Added document with ID: {0}.", addedDocRef.Id));
    });
    C#

    Use the AddAsync() method:

    Dictionary<string, object> city = new Dictionary<string, object>
    {
        { "Name", "Tokyo" },
        { "Country", "Japan" }
    };
    DocumentReference addedDocRef = await db.Collection("cities").AddAsync(city);
    Console.WriteLine("Added document with ID: {0}.", addedDocRef.Id);
    Ruby

    Use the add() method:

    data = {
      name:    "Tokyo",
      country: "Japan"
    }
    
    cities_ref = firestore.col collection_path
    
    added_doc_ref = cities_ref.add data
    puts "Added document with ID: #{added_doc_ref.document_id}."

    In some cases, it can be useful to create a document reference with an auto-generated ID, then use the reference later. For this use case, you can call doc():

    Web version 9

    import { collection, doc, setDoc } from "firebase/firestore"; 
    
    // Add a new document with a generated id
    const newCityRef = doc(collection(db, "cities"));
    
    // later...
    await setDoc(newCityRef, data);

    Web version 8

    // Add a new document with a generated id.
    var newCityRef = db.collection("cities").doc();
    
    // later...
    newCityRef.set(data);
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    let newCityRef = db.collection("cities").document()
    
    // later...
    newCityRef.setData([
        // ...
    ])
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    FIRDocumentReference *newCityRef = [[self.db collectionWithPath:@"cities"] documentWithAutoID];
    // later...
    [newCityRef setData:@{ /* ... */ }];

    Kotlin+KTX

    val data = HashMap<String, Any>()
    
    val newCityRef = db.collection("cities").document()
    
    // Later...
    newCityRef.set(data)
    

    Java

    Map<String, Object> data = new HashMap<>();
    
    DocumentReference newCityRef = db.collection("cities").document();
    
    // Later...
    newCityRef.set(data);
    

    Dart

    // Add a new document with a generated id.
    final data = <String, dynamic>{};
    
    final newCityRef = db.collection("cities").doc();
    
    // Later...
    newCityRef.set(data);
    
    Java
    // Add document data after generating an id.
    DocumentReference addedDocRef = db.collection("cities").document();
    System.out.println("Added document with ID: " + addedDocRef.getId());
    
    // later...
    ApiFuture<WriteResult> writeResult = addedDocRef.set(data);
    Python
    new_city_ref = db.collection(u'cities').document()
    
    # later...
    new_city_ref.set({
        # ...
    })

    Python

    new_city_ref = db.collection("cities").document()
    
    # later...
    await new_city_ref.set(
        {
            # ...
        }
    )
    C++
    DocumentReference new_city_ref = db->Collection("cities").Document();
    Node.js
    const newCityRef = db.collection('cities').doc();
    
    // Later...
    const res = await newCityRef.set({
      // ...
    });
    Go
    ref := client.Collection("cities").NewDoc()
    
    // later...
    _, err := ref.Set(ctx, data)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $addedDocRef = $db->collection('samples/php/cities')->newDocument();
    printf('Added document with ID: %s' . PHP_EOL, $addedDocRef->id());
    $addedDocRef->set($data);
    Unity
    DocumentReference addedDocRef = db.Collection("cities").Document();
    Debug.Log(String.Format("Added document with ID: {0}.", addedDocRef.Id));
    addedDocRef.SetAsync(city).ContinueWithOnMainThread(task => {
    	Debug.Log(String.Format(
    		"Added data to the {0} document in the cities collection.", addedDocRef.Id));
    });
    C#
    DocumentReference addedDocRef = db.Collection("cities").Document();
    Console.WriteLine("Added document with ID: {0}.", addedDocRef.Id);
    await addedDocRef.SetAsync(city);
    Ruby
    cities_ref = firestore.col collection_path
    
    added_doc_ref = cities_ref.doc
    puts "Added document with ID: #{added_doc_ref.document_id}."
    
    added_doc_ref.set data

    Behind the scenes, .add(...) and .doc().set(...) are completely equivalent, so you can use whichever is more convenient.

    Update a document

    To update some fields of a document without overwriting the entire document, use the following language-specific update() methods:

    Web version 9

    Use the updateDoc() method:

    import { doc, updateDoc } from "firebase/firestore";
    
    const washingtonRef = doc(db, "cities", "DC");
    
    // Set the "capital" field of the city 'DC'
    await updateDoc(washingtonRef, {
      capital: true
    });

    Web version 8

    Use the update() method:

    var washingtonRef = db.collection("cities").doc("DC");
    
    // Set the "capital" field of the city 'DC'
    return washingtonRef.update({
        capital: true
    })
    .then(() => {
        console.log("Document successfully updated!");
    })
    .catch((error) => {
        // The document probably doesn't exist.
        console.error("Error updating document: ", error);
    });
    Swift

    Use the updateData() method:

    Note: This product is not available on watchOS and App Clip targets.
    let washingtonRef = db.collection("cities").document("DC")
    
    // Set the "capital" field of the city 'DC'
    washingtonRef.updateData([
        "capital": true
    ]) { err in
        if let err = err {
            print("Error updating document: \(err)")
        } else {
            print("Document successfully updated")
        }
    }
    Objective-C

    Use the updateData: method:

    Note: This product is not available on watchOS and App Clip targets.
    FIRDocumentReference *washingtonRef =
        [[self.db collectionWithPath:@"cities"] documentWithPath:@"DC"];
    // Set the "capital" field of the city
    [washingtonRef updateData:@{
      @"capital": @YES
    } completion:^(NSError * _Nullable error) {
      if (error != nil) {
        NSLog(@"Error updating document: %@", error);
      } else {
        NSLog(@"Document successfully updated");
      }
    }];

    Kotlin+KTX

    Use the update() method:

    val washingtonRef = db.collection("cities").document("DC")
    
    // Set the "isCapital" field of the city 'DC'
    washingtonRef
            .update("capital", true)
            .addOnSuccessListener { Log.d(TAG, "DocumentSnapshot successfully updated!") }
            .addOnFailureListener { e -> Log.w(TAG, "Error updating document", e) }
    

    Java

    Use the update() method:

    DocumentReference washingtonRef = db.collection("cities").document("DC");
    
    // Set the "isCapital" field of the city 'DC'
    washingtonRef
            .update("capital", true)
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Log.d(TAG, "DocumentSnapshot successfully updated!");
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Log.w(TAG, "Error updating document", e);
                }
            });
    

    Dart

    Use the update() method:

    final washingtonRef = db.collection("cites").doc("DC");
    washingtonRef.update({"capital": true}).then(
        (value) => print("DocumentSnapshot successfully updated!"),
        onError: (e) => print("Error updating document $e"));
    Java

    Use the update() method:

    // Update an existing document
    DocumentReference docRef = db.collection("cities").document("DC");
    
    // (async) Update one field
    ApiFuture<WriteResult> future = docRef.update("capital", true);
    
    // ...
    WriteResult result = future.get();
    System.out.println("Write result: " + result);
    Python

    Use the update() method:

    city_ref = db.collection(u'cities').document(u'DC')
    
    # Set the capital field
    city_ref.update({u'capital': True})

    Python

    Use the update() method:

    city_ref = db.collection("cities").document("DC")
    
    # Set the capital field
    await city_ref.update({"capital": True})
    C++

    Use the Update() method:

    DocumentReference washington_ref = db->Collection("cities").Document("DC");
    // Set the "capital" field of the city "DC".
    washington_ref.Update({{"capital", FieldValue::Boolean(true)}});
    Node.js

    Use the update() method:

    const cityRef = db.collection('cities').doc('DC');
    
    // Set the 'capital' field of the city
    const res = await cityRef.update({capital: true});
    Go

    Use the Update() method:

    _, err = client.Collection("cities").Doc("DC").Update(ctx, []firestore.Update{
    	{
    		Path:  "capital",
    		Value: true,
    	},
    })
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    Use the update() method:

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $cityRef = $db->collection('samples/php/cities')->document('DC');
    $cityRef->update([
        ['path' => 'capital', 'value' => true]
    ]);
    Unity

    Use the UpdateAsync() method:

    DocumentReference cityRef = db.Collection("cities").Document("new-city-id");
    Dictionary<string, object> updates = new Dictionary<string, object>
    {
    	{ "Capital", false }
    };
    
    cityRef.UpdateAsync(updates).ContinueWithOnMainThread(task => {
    	Debug.Log(
    		"Updated the Capital field of the new-city-id document in the cities collection.");
    });
    // You can also update a single field with: cityRef.UpdateAsync("Capital", false);
    C#

    Use the UpdateAsync() method:

    DocumentReference cityRef = db.Collection("cities").Document("new-city-id");
    Dictionary<string, object> updates = new Dictionary<string, object>
    {
        { "Capital", false }
    };
    await cityRef.UpdateAsync(updates);
    
    // You can also update a single field with: await cityRef.UpdateAsync("Capital", false);
    Ruby

    Use the update() method:

    city_ref = firestore.doc "#{collection_path}/DC"
    city_ref.update({ capital: true })

    Server Timestamp

    You can set a field in your document to a server timestamp which tracks when the server receives the update.

    Web version 9

    import { updateDoc, serverTimestamp } from "firebase/firestore";
    
    const docRef = doc(db, 'objects', 'some-id');
    
    // Update the timestamp field with the value from the server
    const updateTimestamp = await updateDoc(docRef, {
        timestamp: serverTimestamp()
    });

    Web version 8

    var docRef = db.collection('objects').doc('some-id');
    
    // Update the timestamp field with the value from the server
    var updateTimestamp = docRef.update({
        timestamp: firebase.firestore.FieldValue.serverTimestamp()
    });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    db.collection("objects").document("some-id").updateData([
        "lastUpdated": FieldValue.serverTimestamp(),
    ]) { err in
        if let err = err {
            print("Error updating document: \(err)")
        } else {
            print("Document successfully updated")
        }
    }
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    [[[self.db collectionWithPath:@"objects"] documentWithPath:@"some-id"] updateData:@{
      @"lastUpdated": [FIRFieldValue fieldValueForServerTimestamp]
    } completion:^(NSError * _Nullable error) {
      if (error != nil) {
        NSLog(@"Error updating document: %@", error);
      } else {
        NSLog(@"Document successfully updated");
      }
    }];

    Kotlin+KTX

    // If you're using custom Kotlin objects in Android, add an @ServerTimestamp
    // annotation to a Date field for your custom object classes. This indicates
    // that the Date field should be treated as a server timestamp by the object mapper.
    val docRef = db.collection("objects").document("some-id")
    
    // Update the timestamp field with the value from the server
    val updates = hashMapOf<String, Any>(
            "timestamp" to FieldValue.serverTimestamp()
    )
    
    docRef.update(updates).addOnCompleteListener { }
    

    Java

    // If you're using custom Java objects in Android, add an @ServerTimestamp
    // annotation to a Date field for your custom object classes. This indicates
    // that the Date field should be treated as a server timestamp by the object mapper.
    DocumentReference docRef = db.collection("objects").document("some-id");
    
    // Update the timestamp field with the value from the server
    Map<String,Object> updates = new HashMap<>();
    updates.put("timestamp", FieldValue.serverTimestamp());
    
    docRef.update(updates).addOnCompleteListener(new OnCompleteListener<Void>() {
        // ...
        // ...
    

    Dart

    final docRef = db.collection("objects").doc("some-id");
    final updates = <String, dynamic>{
      "timestamp": FieldValue.serverTimestamp(),
    };
    
    docRef.update(updates).then(
        (value) => print("DocumentSnapshot successfully updated!"),
        onError: (e) => print("Error updating document $e"));
    Java
    DocumentReference docRef = db.collection("objects").document("some-id");
    // Update the timestamp field with the value from the server
    ApiFuture<WriteResult> writeResult = docRef.update("timestamp", FieldValue.serverTimestamp());
    System.out.println("Update time : " + writeResult.get());
    Python
    city_ref = db.collection(u'objects').document(u'some-id')
    city_ref.update({
        u'timestamp': firestore.SERVER_TIMESTAMP
    })

    Python

    city_ref = db.collection("objects").document("some-id")
    await city_ref.update({"timestamp": firestore.SERVER_TIMESTAMP})
    C++
    DocumentReference doc_ref = db->Collection("objects").Document("some-id");
    doc_ref.Update({{"timestamp", FieldValue::ServerTimestamp()}})
        .OnCompletion([](const Future<void>& future) {
          // ...
        });
    Node.js
    // Create a document reference
    const docRef = db.collection('objects').doc('some-id');
    
    // Update the timestamp field with the value from the server
    const res = await docRef.update({
      timestamp: FieldValue.serverTimestamp()
    });
    Go
    _, err := client.Collection("objects").Doc("some-id").Set(ctx, map[string]interface{}{
    	"timestamp": firestore.ServerTimestamp,
    }, firestore.MergeAll)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $docRef = $db->collection('samples/php/objects')->document('some-id');
    $docRef->update([
        ['path' => 'timestamp', 'value' => FieldValue::serverTimestamp()]
    ]);
    Unity
    DocumentReference cityRef = db.Collection("cities").Document("new-city-id");
    cityRef.UpdateAsync("Timestamp", FieldValue.ServerTimestamp)
    	.ContinueWithOnMainThread(task => {
    		Debug.Log(
    			"Updated the Timestamp field of the new-city-id document in the cities "
    			+ "collection.");
    	});
    C#
    DocumentReference cityRef = db.Collection("cities").Document("new-city-id");
    await cityRef.UpdateAsync("Timestamp", Timestamp.GetCurrentTimestamp());
    Ruby
    city_ref = firestore.doc "#{collection_path}/new-city-id"
    city_ref.update({ timestamp: firestore.field_server_time })

    When updating multiple timestamp fields inside of a transaction, each field receives the same server timestamp value.

    Update fields in nested objects

    If your document contains nested objects, you can use "dot notation" to reference nested fields within the document when you call update():

    Web version 9

    import { doc, setDoc, updateDoc } from "firebase/firestore"; 
    
    // Create an initial document to update.
    const frankDocRef = doc(db, "users", "frank");
    await setDoc(frankDocRef, {
        name: "Frank",
        favorites: { food: "Pizza", color: "Blue", subject: "recess" },
        age: 12
    });
    
    // To update age and favorite color:
    await updateDoc(frankDocRef, {
        "age": 13,
        "favorites.color": "Red"
    });

    Web version 8

    // Create an initial document to update.
    var frankDocRef = db.collection("users").doc("frank");
    frankDocRef.set({
        name: "Frank",
        favorites: { food: "Pizza", color: "Blue", subject: "recess" },
        age: 12
    });
    
    // To update age and favorite color:
    db.collection("users").doc("frank").update({
        "age": 13,
        "favorites.color": "Red"
    })
    .then(() => {
        console.log("Document successfully updated!");
    });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    // Create an initial document to update.
    let frankDocRef = db.collection("users").document("frank")
    frankDocRef.setData([
        "name": "Frank",
        "favorites": [ "food": "Pizza", "color": "Blue", "subject": "recess" ],
        "age": 12
        ])
    
    // To update age and favorite color:
    db.collection("users").document("frank").updateData([
        "age": 13,
        "favorites.color": "Red"
    ]) { err in
        if let err = err {
            print("Error updating document: \(err)")
        } else {
            print("Document successfully updated")
        }
    }
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    // Create an initial document to update.
    FIRDocumentReference *frankDocRef =
        [[self.db collectionWithPath:@"users"] documentWithPath:@"frank"];
    [frankDocRef setData:@{
      @"name": @"Frank",
      @"favorites": @{
        @"food": @"Pizza",
        @"color": @"Blue",
        @"subject": @"recess"
      },
      @"age": @12
    }];
    // To update age and favorite color:
    [frankDocRef updateData:@{
      @"age": @13,
      @"favorites.color": @"Red",
    } completion:^(NSError * _Nullable error) {
      if (error != nil) {
        NSLog(@"Error updating document: %@", error);
      } else {
        NSLog(@"Document successfully updated");
      }
    }];

    Kotlin+KTX

    // Assume the document contains:
    // {
    //   name: "Frank",
    //   favorites: { food: "Pizza", color: "Blue", subject: "recess" }
    //   age: 12
    // }
    //
    // To update age and favorite color:
    db.collection("users").document("frank")
            .update(mapOf(
                    "age" to 13,
                    "favorites.color" to "Red"
            ))
    

    Java

    // Assume the document contains:
    // {
    //   name: "Frank",
    //   favorites: { food: "Pizza", color: "Blue", subject: "recess" }
    //   age: 12
    // }
    //
    // To update age and favorite color:
    db.collection("users").document("frank")
            .update(
                    "age", 13,
                    "favorites.color", "Red"
            );
    

    Dart

    // Assume the document contains:
    // {
    //   name: "Frank",
    //   favorites: { food: "Pizza", color: "Blue", subject: "recess" }
    //   age: 12
    // }
    db
        .collection("users")
        .doc("frank")
        .update({"age": 13, "favorites.color": "Red"});
    Java
    // Create an initial document to update
    DocumentReference frankDocRef = db.collection("users").document("frank");
    Map<String, Object> initialData = new HashMap<>();
    initialData.put("name", "Frank");
    initialData.put("age", 12);
    
    Map<String, Object> favorites = new HashMap<>();
    favorites.put("food", "Pizza");
    favorites.put("color", "Blue");
    favorites.put("subject", "Recess");
    initialData.put("favorites", favorites);
    
    ApiFuture<WriteResult> initialResult = frankDocRef.set(initialData);
    // Confirm that data has been successfully saved by blocking on the operation
    initialResult.get();
    
    // Update age and favorite color
    Map<String, Object> updates = new HashMap<>();
    updates.put("age", 13);
    updates.put("favorites.color", "Red");
    
    // Async update document
    ApiFuture<WriteResult> writeResult = frankDocRef.update(updates);
    // ...
    System.out.println("Update time : " + writeResult.get().getUpdateTime());
    Python
    # Create an initial document to update
    frank_ref = db.collection(u'users').document(u'frank')
    frank_ref.set({
        u'name': u'Frank',
        u'favorites': {
            u'food': u'Pizza',
            u'color': u'Blue',
            u'subject': u'Recess'
        },
        u'age': 12
    })
    
    # Update age and favorite color
    frank_ref.update({
        u'age': 13,
        u'favorites.color': u'Red'
    })

    Python

    # Create an initial document to update
    frank_ref = db.collection("users").document("frank")
    await frank_ref.set(
        {
            "name": "Frank",
            "favorites": {"food": "Pizza", "color": "Blue", "subject": "Recess"},
            "age": 12,
        }
    )
    
    # Update age and favorite color
    await frank_ref.update({"age": 13, "favorites.color": "Red"})
    C++
    // Assume the document contains:
    // {
    //   name: "Frank",
    //   favorites: { food: "Pizza", color: "Blue", subject: "recess" }
    //   age: 12
    // }
    //
    // To update age and favorite color:
    db->Collection("users").Document("frank").Update({
        {"age", FieldValue::Integer(13)},
        {"favorites.color", FieldValue::String("red")},
    });
    Node.js
    const initialData = {
      name: 'Frank',
      age: 12,
      favorites: {
        food: 'Pizza',
        color: 'Blue',
        subject: 'recess'
      }
    };
    
    // ...
    const res = await db.collection('users').doc('Frank').update({
      age: 13,
      'favorites.color': 'Red'
    });
    Go
    initialData := map[string]interface{}{
    	"name": "Frank",
    	"age":  12,
    	"favorites": map[string]interface{}{
    		"food":    "Pizza",
    		"color":   "Blue",
    		"subject": "recess",
    	},
    }
    
    // ...
    
    _, err := client.Collection("users").Doc("frank").Set(ctx, map[string]interface{}{
    	"age": 13,
    	"favorites": map[string]interface{}{
    		"color": "Red",
    	},
    }, firestore.MergeAll)
    if err != nil {
    	// Handle any errors in an appropriate way, such as returning them.
    	log.Printf("An error has occurred: %s", err)
    }
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    // Create an initial document to update
    $frankRef = $db->collection('samples/php/users')->document('frank');
    $frankRef->set([
        'first' => 'Frank',
        'last' => 'Franklin',
        'favorites' => ['food' => 'Pizza', 'color' => 'Blue', 'subject' => 'Recess'],
        'age' => 12
    ]);
    
    // Update age and favorite color
    $frankRef->update([
        ['path' => 'age', 'value' => 13],
        ['path' => 'favorites.color', 'value' => 'Red']
    ]);
    Unity
    DocumentReference frankDocRef = db.Collection("users").Document("frank");
    Dictionary<string, object> initialData = new Dictionary<string, object>
    {
    	{ "Name", "Frank" },
    	{ "Age", 12 }
    };
    
    Dictionary<string, object> favorites = new Dictionary<string, object>
    {
    	{ "Food", "Pizza" },
    	{ "Color", "Blue" },
    	{ "Subject", "Recess" },
    };
    initialData.Add("Favorites", favorites);
    frankDocRef.SetAsync(initialData).ContinueWithOnMainThread(task => {
    
    	// Update age and favorite color
    	Dictionary<string, object> updates = new Dictionary<string, object>
    	{
    		{ "Age", 13 },
    		{ "Favorites.Color", "Red" },
    	};
    
    	// Asynchronously update the document
    	return frankDocRef.UpdateAsync(updates);
    }).ContinueWithOnMainThread(task => {
    	Debug.Log(
    		"Updated the age and favorite color fields of the Frank document in "
    		+ "the users collection.");
    });
    C#
    DocumentReference frankDocRef = db.Collection("users").Document("frank");
    Dictionary<string, object> initialData = new Dictionary<string, object>
    {
        { "Name", "Frank" },
        { "Age", 12 }
    };
    
    Dictionary<string, object> favorites = new Dictionary<string, object>
    {
        { "Food", "Pizza" },
        { "Color", "Blue" },
        { "Subject", "Recess" },
    };
    initialData.Add("Favorites", favorites);
    await frankDocRef.SetAsync(initialData);
    
    // Update age and favorite color
    Dictionary<string, object> updates = new Dictionary<string, object>
    {
        { "Age", 13 },
        { "Favorites.Color", "Red" },
    };
    
    // Asynchronously update the document
    await frankDocRef.UpdateAsync(updates);
    Ruby
    # Create an initial document to update
    frank_ref = firestore.doc "#{collection_path}/frank"
    frank_ref.set(
      {
        name:      "Frank",
        favorites: {
          food:    "Pizza",
          color:   "Blue",
          subject: "Recess"
        },
        age:       12
      }
    )
    
    # Update age and favorite color
    frank_ref.update({ age: 13, "favorites.color": "Red" })

    Dot notation allows you to update a single nested field without overwriting other nested field. If you update a nested field without dot notation, you will overwrite the entire map field, for example:

    Web
    
    // Create our initial doc
    db.collection("users").doc("frank").set({
      name: "Frank",
      favorites: {
        food: "Pizza",
        color: "Blue",
        subject: "Recess"
      },
      age: 12
    }).then(function() {
      console.log("Frank created");
    });
    
    // Update the doc without using dot notation.
    // Notice the map value for favorites.
    db.collection("users").doc("frank").update({
      favorites: {
        food: "Ice Cream"
      }
    }).then(function() {
      console.log("Frank food updated");
    });
    
    /*
    Ending State, favorite.color and favorite.subject are no longer present:
    /users
        /frank
            {
                name: "Frank",
                favorites: {
                    food: "Ice Cream",
                },
                age: 12
            }
     */
    

    Update elements in an array

    If your document contains an array field, you can use arrayUnion() and arrayRemove() to add and remove elements. arrayUnion() adds elements to an array but only elements not already present. arrayRemove() removes all instances of each given element.

    Web version 9

    import { doc, updateDoc, arrayUnion, arrayRemove } from "firebase/firestore";
    
    const washingtonRef = doc(db, "cities", "DC");
    
    // Atomically add a new region to the "regions" array field.
    await updateDoc(washingtonRef, {
        regions: arrayUnion("greater_virginia")
    });
    
    // Atomically remove a region from the "regions" array field.
    await updateDoc(washingtonRef, {
        regions: arrayRemove("east_coast")
    });

    Web version 8

    var washingtonRef = db.collection("cities").doc("DC");
    
    // Atomically add a new region to the "regions" array field.
    washingtonRef.update({
        regions: firebase.firestore.FieldValue.arrayUnion("greater_virginia")
    });
    
    // Atomically remove a region from the "regions" array field.
    washingtonRef.update({
        regions: firebase.firestore.FieldValue.arrayRemove("east_coast")
    });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    let washingtonRef = db.collection("cities").document("DC")
    
    // Atomically add a new region to the "regions" array field.
    washingtonRef.updateData([
        "regions": FieldValue.arrayUnion(["greater_virginia"])
    ])
    
    // Atomically remove a region from the "regions" array field.
    washingtonRef.updateData([
        "regions": FieldValue.arrayRemove(["east_coast"])
    ])
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    FIRDocumentReference *washingtonRef =
        [[self.db collectionWithPath:@"cities"] documentWithPath:@"DC"];
    
    // Atomically add a new region to the "regions" array field.
    [washingtonRef updateData:@{
      @"regions": [FIRFieldValue fieldValueForArrayUnion:@[@"greater_virginia"]]
    }];
    
    // Atomically remove a new region to the "regions" array field.
    [washingtonRef updateData:@{
      @"regions": [FIRFieldValue fieldValueForArrayRemove:@[@"east_coast"]]
    }];

    Kotlin+KTX

    val washingtonRef = db.collection("cities").document("DC")
    
    // Atomically add a new region to the "regions" array field.
    washingtonRef.update("regions", FieldValue.arrayUnion("greater_virginia"))
    
    // Atomically remove a region from the "regions" array field.
    washingtonRef.update("regions", FieldValue.arrayRemove("east_coast"))
    

    Java

    DocumentReference washingtonRef = db.collection("cities").document("DC");
    
    // Atomically add a new region to the "regions" array field.
    washingtonRef.update("regions", FieldValue.arrayUnion("greater_virginia"));
    
    // Atomically remove a region from the "regions" array field.
    washingtonRef.update("regions", FieldValue.arrayRemove("east_coast"));
    

    Dart

    final washingtonRef = db.collection("cities").doc("DC");
    
    // Atomically add a new region to the "regions" array field.
    washingtonRef.update({
      "regions": FieldValue.arrayUnion(["greater_virginia"]),
    });
    
    // Atomically remove a region from the "regions" array field.
    washingtonRef.update({
      "regions": FieldValue.arrayRemove(["east_coast"]),
    });
    Java
    DocumentReference washingtonRef = db.collection("cities").document("DC");
    
    // Atomically add a new region to the "regions" array field.
    ApiFuture<WriteResult> arrayUnion =
        washingtonRef.update("regions", FieldValue.arrayUnion("greater_virginia"));
    System.out.println("Update time : " + arrayUnion.get());
    
    // Atomically remove a region from the "regions" array field.
    ApiFuture<WriteResult> arrayRm =
        washingtonRef.update("regions", FieldValue.arrayRemove("east_coast"));
    System.out.println("Update time : " + arrayRm.get());
    Python
    city_ref = db.collection(u'cities').document(u'DC')
    
    # Atomically add a new region to the 'regions' array field.
    city_ref.update({u'regions': firestore.ArrayUnion([u'greater_virginia'])})
    
    # // Atomically remove a region from the 'regions' array field.
    city_ref.update({u'regions': firestore.ArrayRemove([u'east_coast'])})

    Python

    city_ref = db.collection("cities").document("DC")
    
    # Atomically add a new region to the 'regions' array field.
    await city_ref.update({"regions": firestore.ArrayUnion(["greater_virginia"])})
    
    # // Atomically remove a region from the 'regions' array field.
    await city_ref.update({"regions": firestore.ArrayRemove(["east_coast"])})
    C++
    // This is not yet supported.
    
    Node.js
    // ...
    const washingtonRef = db.collection('cities').doc('DC');
    
    // Atomically add a new region to the "regions" array field.
    const unionRes = await washingtonRef.update({
      regions: FieldValue.arrayUnion('greater_virginia')
    });
    // Atomically remove a region from the "regions" array field.
    const removeRes = await washingtonRef.update({
      regions: FieldValue.arrayRemove('east_coast')
    });
    
    // To add or remove multiple items, pass multiple arguments to arrayUnion/arrayRemove
    const multipleUnionRes = await washingtonRef.update({
      regions: FieldValue.arrayUnion('south_carolina', 'texas')
      // Alternatively, you can use spread operator in ES6 syntax
      // const newRegions = ['south_carolina', 'texas']
      // regions: FieldValue.arrayUnion(...newRegions)
    });
    Go
    // Not supported yet
    
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $cityRef = $db->collection('samples/php/cities')->document('DC');
    
    // Atomically add a new region to the "regions" array field.
    $cityRef->update([
        ['path' => 'regions', 'value' => FieldValue::arrayUnion(['greater_virginia'])]
    ]);
    
    // Atomically remove a region from the "regions" array field.
    $cityRef->update([
        ['path' => 'regions', 'value' => FieldValue::arrayRemove(['east_coast'])]
    ]);
    Unity
    // This is not yet supported in the Unity SDK
      
    C#
    DocumentReference washingtonRef = db.Collection("cities").Document("DC");
    
    // Atomically add a new region to the "regions" array field.
    await washingtonRef.UpdateAsync("Regions", FieldValue.ArrayUnion("greater_virginia"));
    
    // Atomically remove a region from the "regions" array field.
    await washingtonRef.UpdateAsync("Regions", FieldValue.ArrayRemove("east_coast"));
    Ruby
    // Not supported yet
    

    Increment a numeric value

    You can increment or decrement a numeric field value as shown in the following example. An increment operation increases or decreases the current value of a field by the given amount.

    Web version 9

    import { doc, updateDoc, increment } from "firebase/firestore";
    
    const washingtonRef = doc(db, "cities", "DC");
    
    // Atomically increment the population of the city by 50.
    await updateDoc(washingtonRef, {
        population: increment(50)
    });

    Web version 8

    var washingtonRef = db.collection('cities').doc('DC');
    
    // Atomically increment the population of the city by 50.
    washingtonRef.update({
        population: firebase.firestore.FieldValue.increment(50)
    });
    Swift
    Note: This product is not available on watchOS and App Clip targets.
    let washingtonRef = db.collection("cities").document("DC")
    
    // Atomically increment the population of the city by 50.
    // Note that increment() with no arguments increments by 1.
    washingtonRef.updateData([
        "population": FieldValue.increment(Int64(50))
    ])
    Objective-C
    Note: This product is not available on watchOS and App Clip targets.
    FIRDocumentReference *washingtonRef =
        [[self.db collectionWithPath:@"cities"] documentWithPath:@"DC"];
    
    // Atomically increment the population of the city by 50.
    // Note that increment() with no arguments increments by 1.
    [washingtonRef updateData:@{
      @"population": [FIRFieldValue fieldValueForIntegerIncrement:50]
    }];

    Kotlin+KTX

    val washingtonRef = db.collection("cities").document("DC")
    
    // Atomically increment the population of the city by 50.
    washingtonRef.update("population", FieldValue.increment(50))
    

    Java

    DocumentReference washingtonRef = db.collection("cities").document("DC");
    
    // Atomically increment the population of the city by 50.
    washingtonRef.update("population", FieldValue.increment(50));
    

    Dart

    var washingtonRef = db.collection('cities').doc('DC');
    
    // Atomically increment the population of the city by 50.
    washingtonRef.update(
      {"population": FieldValue.increment(50)},
    );
    Java
    DocumentReference washingtonRef = db.collection("cities").document("DC");
    
    // Atomically increment the population of the city by 50.
    final ApiFuture<WriteResult> updateFuture =
        washingtonRef.update("population", FieldValue.increment(50));
    Python
    washington_ref = db.collection(u'cities').document(u'DC')
    
    washington_ref.update({"population": firestore.Increment(50)})

    Python

    washington_ref = db.collection("cities").document("DC")
    
    washington_ref.update({"population": firestore.Increment(50)})
    C++
    // This is not yet supported.
    
    Node.js
    // ...
    const washingtonRef = db.collection('cities').doc('DC');
    
    // Atomically increment the population of the city by 50.
    const res = await washingtonRef.update({
      population: FieldValue.increment(50)
    });
    Go
    import (
    	"context"
    	"fmt"
    
    	"cloud.google.com/go/firestore"
    )
    
    // updateDocumentIncrement increments the population of the city document in the
    // cities collection by 50.
    func updateDocumentIncrement(projectID, city string) error {
    	// projectID := "my-project"
    
    	ctx := context.Background()
    
    	client, err := firestore.NewClient(ctx, projectID)
    	if err != nil {
    		return fmt.Errorf("firestore.NewClient: %v", err)
    	}
    	defer client.Close()
    
    	dc := client.Collection("cities").Doc(city)
    	_, err = dc.Update(ctx, []firestore.Update{
    		{Path: "population", Value: firestore.Increment(50)},
    	})
    	if err != nil {
    		return fmt.Errorf("Update: %v", err)
    	}
    
    	return nil
    }
    
    PHP

    PHP

    For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.

    $cityRef = $db->collection('samples/php/cities')->document('DC');
    
    // Atomically increment the population of the city by 50.
    $cityRef->update([
        ['path' => 'regions', 'value' => FieldValue::increment(50)]
    ]);
    Unity
    // This is not yet supported in the Unity SDK.
      
    C#
    DocumentReference washingtonRef = db.Collection("cities").Document("DC");
    
    // Atomically increment the population of the city by 50.
    await washingtonRef.UpdateAsync("Regions", FieldValue.Increment(50));
    Ruby
    city_ref = firestore.doc "#{collection_path}/DC"
    city_ref.update({ population: firestore.field_increment(50) })

    Increment operations are useful for implementing counters, but keep in mind that you can update a single document only once per second. If you need to update your counter above this rate, see the Distributed counters page.