Daten mit Cloud Firestore abrufen

Es gibt drei Möglichkeiten, in Cloud Firestore gespeicherte Daten abzurufen. Beide Methoden können für Dokumente, Dokumentensammlungen oder Ergebnisse von Abfragen genutzt werden:

  • Rufen Sie eine Methode auf, um die Daten einmal abzurufen.
  • Legen Sie einen Listener fest, der Ereignisse zu Datenänderungen empfangen soll.
  • Firestore-Snapshot-Daten per Datenpaket aus einer externen Quelle im Bulk-Verfahren laden Weitere Informationen finden Sie im Dokument zu Bundles.

Wenn Sie einen Listener angeben, sendet Cloud Firestore Ihrem Listener einen ersten Snapshot der Daten und anschließend jedes Mal, wenn sich das Dokument ändert, einen weiteren Snapshot.

Hinweis

Weitere Informationen zum Erstellen einer Cloud Firestore-Datenbank finden Sie unter Einstieg in Cloud Firestore.

Cloud Firestore initialisieren

Initialisieren Sie eine Instanz von Cloud Firestore:

Web

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);

Ersetzen Sie FIREBASE_CONFIGURATION durch die firebaseConfig Ihrer Webanwendung.

Informationen zum dauerhaften Sichern von Daten für den Fall, dass die Verbindung des Geräts unterbrochen wird, finden Sie in der Dokumentation Offlinedaten aktivieren.

Web

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();

Ersetzen Sie FIREBASE_CONFIGURATION durch die firebaseConfig Ihrer Webanwendung.

Informationen zum dauerhaften Sichern von Daten für den Fall, dass die Verbindung des Geräts unterbrochen wird, finden Sie in der Dokumentation Offlinedaten aktivieren.

Swift
Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
import FirebaseCore
import FirebaseFirestore
 
FirebaseApp.configure()

let db = Firestore.firestore()
AppDelegate.swift
Objective-C
Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
@import FirebaseCore;
@import FirebaseFirestore;

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

Kotlin

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

Java

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

Dart

db = FirebaseFirestore.instance;
Java
Das Cloud Firestore SDK wird je nach Umgebung unterschiedlich initialisiert. Im Folgenden finden Sie die gängigsten Methoden. Eine vollständige Referenz finden Sie unter Admin SDK initialisieren.
  • Am Google Cloud initialisieren 
    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();
  • Auf eigenem Server initialisieren

    Wenn Sie das Firebase Admin SDK auf Ihrem eigenen Server verwenden möchten, verwenden Sie ein Dienstkonto.

    Gehen Sie in der Google Cloud Console zu IAM & Verwaltung > Dienstkonten. Generieren Sie einen neuen privaten Schlüssel und speichern Sie die JSON-Datei. Initialisieren Sie dann das SDK mit der Datei: 

    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
    Das Cloud Firestore SDK wird je nach Umgebung unterschiedlich initialisiert. Im Folgenden finden Sie die gängigsten Methoden. Eine vollständige Referenz finden Sie unter Admin SDK initialisieren.
  • Am Google Cloud initialisieren 
    import firebase_admin
from firebase_admin import firestore

# Application Default credentials are automatically created.
app = firebase_admin.initialize_app()
db = firestore.client()
    firestore.py

    Sie können auch vorhandene Standardanmeldedaten für Anwendungen verwenden, um das SDK zu initialisieren.

    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()
    firestore.py
  • Auf eigenem Server initialisieren

    Wenn Sie das Firebase Admin SDK auf Ihrem eigenen Server verwenden möchten, verwenden Sie ein Dienstkonto.

    Gehen Sie in der Google Cloud Console zu IAM & Verwaltung > Dienstkonten. Generieren Sie einen neuen privaten Schlüssel und speichern Sie die JSON-Datei. Initialisieren Sie dann das SDK mit der Datei: 

    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()
    firestore.py

    • Python

    Das Cloud Firestore SDK wird je nach Umgebung unterschiedlich initialisiert. Im Folgenden finden Sie die gängigsten Methoden. Eine vollständige Referenz finden Sie unter Admin SDK initialisieren.
  • Am Google Cloud initialisieren 
    import firebase_admin
from firebase_admin import firestore_async

# Application Default credentials are automatically created.
app = firebase_admin.initialize_app()
db = firestore_async.client()
    firestore_async.py

    Sie können auch vorhandene Standardanmeldedaten für Anwendungen verwenden, um das SDK zu initialisieren.

    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()
    firestore_async.py
  • Auf eigenem Server initialisieren

    Wenn Sie das Firebase Admin SDK auf Ihrem eigenen Server verwenden möchten, verwenden Sie ein Dienstkonto.

    Gehen Sie in der Google Cloud Console zu IAM & Verwaltung > Dienstkonten. Generieren Sie einen neuen privaten Schlüssel und speichern Sie die JSON-Datei. Initialisieren Sie dann das SDK mit der Datei: 

    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()
    firestore_async.py
    • C++
    // Make sure the call to `Create()` happens some time before you call Firestore::GetInstance().
App::Create();
Firestore* db = Firestore::GetInstance();
    AppDelegate.mm
    Node.js
    Das Cloud Firestore SDK wird je nach Umgebung unterschiedlich initialisiert. Im Folgenden finden Sie die gängigsten Methoden. Eine vollständige Referenz finden Sie unter Admin SDK initialisieren.
    • Am Cloud Functions initialisieren 
      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
const { getFirestore, Timestamp, FieldValue, Filter } = require('firebase-admin/firestore');
       
      initializeApp();

const db = getFirestore();

      index.js
    • Am Google Cloud initialisieren 
      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
const { getFirestore, Timestamp, FieldValue, Filter } = require('firebase-admin/firestore');
       
      initializeApp({
  credential: applicationDefault()
});

const db = getFirestore();
      index.js
    • Auf eigenem Server initialisieren

      Wenn Sie das Firebase Admin SDK auf Ihrem eigenen Server (oder in einer anderen Node.js-Umgebung) verwenden möchten, verwenden Sie ein Dienstkonto. Klicken Sie in der Google Cloud Console auf IAM & Verwaltung > Dienstkonten. Generieren Sie einen neuen privaten Schlüssel und speichern Sie die JSON-Datei. Initialisieren Sie dann das SDK mit der Datei: 

      const { initializeApp, applicationDefault, cert } = require('firebase-admin/app');
const { getFirestore, Timestamp, FieldValue, Filter } = require('firebase-admin/firestore');
       
      const serviceAccount = require('./path/to/serviceAccountKey.json');

initializeApp({
  credential: cert(serviceAccount)
});

const db = getFirestore();

      index.js
    Go
    Das Cloud Firestore SDK wird je nach Umgebung unterschiedlich initialisiert. Im Folgenden finden Sie die gängigsten Methoden. Eine vollständige Referenz finden Sie unter Admin SDK initialisieren.
  • Am Google Cloud initialisieren 
    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()
  • Auf eigenem Server initialisieren

    Wenn Sie das Firebase Admin SDK auf Ihrem eigenen Server verwenden möchten, verwenden Sie ein Dienstkonto.

    Gehen Sie in der Google Cloud Console zu IAM & Verwaltung > Dienstkonten. Generieren Sie einen neuen privaten Schlüssel und speichern Sie die JSON-Datei. Initialisieren Sie dann das SDK mit der Datei: 

    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

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    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);
    }
}
    setup_client_create.php
    Einheit
    using Firebase.Firestore;
using Firebase.Extensions;
     
    FirebaseFirestore db = FirebaseFirestore.DefaultInstance;
    C#

    C#

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    FirestoreDb db = FirestoreDb.Create(project);
Console.WriteLine("Created Cloud Firestore client with project ID: {0}", project);
    Program.cs
    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."
    quickstart.rb

    Beispieldaten

    Schreiben zuerst einige Daten über Städte, damit wir verschiedene Arten betrachten können, wie sie gelesen werden können:

    Web

    import { collection, doc, setDoc } from "firebase/firestore"; 

const citiesRef = collection(db, "cities");

await setDoc(doc(citiesRef, "SF"), {
    name: "San Francisco", state: "CA", country: "USA",
    capital: false, population: 860000,
    regions: ["west_coast", "norcal"] });
await setDoc(doc(citiesRef, "LA"), {
    name: "Los Angeles", state: "CA", country: "USA",
    capital: false, population: 3900000,
    regions: ["west_coast", "socal"] });
await setDoc(doc(citiesRef, "DC"), {
    name: "Washington, D.C.", state: null, country: "USA",
    capital: true, population: 680000,
    regions: ["east_coast"] });
await setDoc(doc(citiesRef, "TOK"), {
    name: "Tokyo", state: null, country: "Japan",
    capital: true, population: 9000000,
    regions: ["kanto", "honshu"] });
await setDoc(doc(citiesRef, "BJ"), {
    name: "Beijing", state: null, country: "China",
    capital: true, population: 21500000,
    regions: ["jingjinji", "hebei"] });
    example_data.js

    Web

    var citiesRef = db.collection("cities");

citiesRef.doc("SF").set({
    name: "San Francisco", state: "CA", country: "USA",
    capital: false, population: 860000,
    regions: ["west_coast", "norcal"] });
citiesRef.doc("LA").set({
    name: "Los Angeles", state: "CA", country: "USA",
    capital: false, population: 3900000,
    regions: ["west_coast", "socal"] });
citiesRef.doc("DC").set({
    name: "Washington, D.C.", state: null, country: "USA",
    capital: true, population: 680000,
    regions: ["east_coast"] });
citiesRef.doc("TOK").set({
    name: "Tokyo", state: null, country: "Japan",
    capital: true, population: 9000000,
    regions: ["kanto", "honshu"] });
citiesRef.doc("BJ").set({
    name: "Beijing", state: null, country: "China",
    capital: true, population: 21500000,
    regions: ["jingjinji", "hebei"] });
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    let citiesRef = db.collection("cities")

citiesRef.document("SF").setData([
  "name": "San Francisco",
  "state": "CA",
  "country": "USA",
  "capital": false,
  "population": 860000,
  "regions": ["west_coast", "norcal"]
])
citiesRef.document("LA").setData([
  "name": "Los Angeles",
  "state": "CA",
  "country": "USA",
  "capital": false,
  "population": 3900000,
  "regions": ["west_coast", "socal"]
])
citiesRef.document("DC").setData([
  "name": "Washington D.C.",
  "country": "USA",
  "capital": true,
  "population": 680000,
  "regions": ["east_coast"]
])
citiesRef.document("TOK").setData([
  "name": "Tokyo",
  "country": "Japan",
  "capital": true,
  "population": 9000000,
  "regions": ["kanto", "honshu"]
])
citiesRef.document("BJ").setData([
  "name": "Beijing",
  "country": "China",
  "capital": true,
  "population": 21500000,
  "regions": ["jingjinji", "hebei"]
])
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"];
[[citiesRef documentWithPath:@"SF"] setData:@{
  @"name": @"San Francisco",
  @"state": @"CA",
  @"country": @"USA",
  @"capital": @(NO),
  @"population": @860000,
  @"regions": @[@"west_coast", @"norcal"]
}];
[[citiesRef documentWithPath:@"LA"] setData:@{
  @"name": @"Los Angeles",
  @"state": @"CA",
  @"country": @"USA",
  @"capital": @(NO),
  @"population": @3900000,
  @"regions": @[@"west_coast", @"socal"]
}];
[[citiesRef documentWithPath:@"DC"] setData:@{
  @"name": @"Washington D.C.",
  @"country": @"USA",
  @"capital": @(YES),
  @"population": @680000,
  @"regions": @[@"east_coast"]
}];
[[citiesRef documentWithPath:@"TOK"] setData:@{
  @"name": @"Tokyo",
  @"country": @"Japan",
  @"capital": @(YES),
  @"population": @9000000,
  @"regions": @[@"kanto", @"honshu"]
}];
[[citiesRef documentWithPath:@"BJ"] setData:@{
  @"name": @"Beijing",
  @"country": @"China",
  @"capital": @(YES),
  @"population": @21500000,
  @"regions": @[@"jingjinji", @"hebei"]
}];
    ViewController.m

    Kotlin

    val cities = db.collection("cities")

val data1 = hashMapOf(
    "name" to "San Francisco",
    "state" to "CA",
    "country" to "USA",
    "capital" to false,
    "population" to 860000,
    "regions" to listOf("west_coast", "norcal"),
)
cities.document("SF").set(data1)

val data2 = hashMapOf(
    "name" to "Los Angeles",
    "state" to "CA",
    "country" to "USA",
    "capital" to false,
    "population" to 3900000,
    "regions" to listOf("west_coast", "socal"),
)
cities.document("LA").set(data2)

val data3 = hashMapOf(
    "name" to "Washington D.C.",
    "state" to null,
    "country" to "USA",
    "capital" to true,
    "population" to 680000,
    "regions" to listOf("east_coast"),
)
cities.document("DC").set(data3)

val data4 = hashMapOf(
    "name" to "Tokyo",
    "state" to null,
    "country" to "Japan",
    "capital" to true,
    "population" to 9000000,
    "regions" to listOf("kanto", "honshu"),
)
cities.document("TOK").set(data4)

val data5 = hashMapOf(
    "name" to "Beijing",
    "state" to null,
    "country" to "China",
    "capital" to true,
    "population" to 21500000,
    "regions" to listOf("jingjinji", "hebei"),
)
cities.document("BJ").set(data5)
    DocSnippets.kt

    Java

    CollectionReference cities = db.collection("cities");

Map<String, Object> data1 = new HashMap<>();
data1.put("name", "San Francisco");
data1.put("state", "CA");
data1.put("country", "USA");
data1.put("capital", false);
data1.put("population", 860000);
data1.put("regions", Arrays.asList("west_coast", "norcal"));
cities.document("SF").set(data1);

Map<String, Object> data2 = new HashMap<>();
data2.put("name", "Los Angeles");
data2.put("state", "CA");
data2.put("country", "USA");
data2.put("capital", false);
data2.put("population", 3900000);
data2.put("regions", Arrays.asList("west_coast", "socal"));
cities.document("LA").set(data2);

Map<String, Object> data3 = new HashMap<>();
data3.put("name", "Washington D.C.");
data3.put("state", null);
data3.put("country", "USA");
data3.put("capital", true);
data3.put("population", 680000);
data3.put("regions", Arrays.asList("east_coast"));
cities.document("DC").set(data3);

Map<String, Object> data4 = new HashMap<>();
data4.put("name", "Tokyo");
data4.put("state", null);
data4.put("country", "Japan");
data4.put("capital", true);
data4.put("population", 9000000);
data4.put("regions", Arrays.asList("kanto", "honshu"));
cities.document("TOK").set(data4);

Map<String, Object> data5 = new HashMap<>();
data5.put("name", "Beijing");
data5.put("state", null);
data5.put("country", "China");
data5.put("capital", true);
data5.put("population", 21500000);
data5.put("regions", Arrays.asList("jingjinji", "hebei"));
cities.document("BJ").set(data5);
    DocSnippets.java

    Dart

    final cities = db.collection("cities");
final data1 = <String, dynamic>{
  "name": "San Francisco",
  "state": "CA",
  "country": "USA",
  "capital": false,
  "population": 860000,
  "regions": ["west_coast", "norcal"]
};
cities.doc("SF").set(data1);

final data2 = <String, dynamic>{
  "name": "Los Angeles",
  "state": "CA",
  "country": "USA",
  "capital": false,
  "population": 3900000,
  "regions": ["west_coast", "socal"],
};
cities.doc("LA").set(data2);

final data3 = <String, dynamic>{
  "name": "Washington D.C.",
  "state": null,
  "country": "USA",
  "capital": true,
  "population": 680000,
  "regions": ["east_coast"]
};
cities.doc("DC").set(data3);

final data4 = <String, dynamic>{
  "name": "Tokyo",
  "state": null,
  "country": "Japan",
  "capital": true,
  "population": 9000000,
  "regions": ["kanto", "honshu"]
};
cities.doc("TOK").set(data4);

final data5 = <String, dynamic>{
  "name": "Beijing",
  "state": null,
  "country": "China",
  "capital": true,
  "population": 21500000,
  "regions": ["jingjinji", "hebei"],
};
cities.doc("BJ").set(data5);
    firestore.dart
    Java
    CollectionReference cities = db.collection("cities");
List<ApiFuture<WriteResult>> futures = new ArrayList<>();
futures.add(
    cities
        .document("SF")
        .set(
            new City(
                "San Francisco",
                "CA",
                "USA",
                false,
                860000L,
                Arrays.asList("west_coast", "norcal"))));
futures.add(
    cities
        .document("LA")
        .set(
            new City(
                "Los Angeles",
                "CA",
                "USA",
                false,
                3900000L,
                Arrays.asList("west_coast", "socal"))));
futures.add(
    cities
        .document("DC")
        .set(
            new City(
                "Washington D.C.", null, "USA", true, 680000L, Arrays.asList("east_coast"))));
futures.add(
    cities
        .document("TOK")
        .set(
            new City(
                "Tokyo", null, "Japan", true, 9000000L, Arrays.asList("kanto", "honshu"))));
futures.add(
    cities
        .document("BJ")
        .set(
            new City(
                "Beijing",
                null,
                "China",
                true,
                21500000L,
                Arrays.asList("jingjinji", "hebei"))));
// (optional) block on operation
ApiFutures.allAsList(futures).get();
    RetrieveDataSnippets.java
    Python
    class City:
    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}\
            )"
     
    cities_ref = db.collection("cities")
cities_ref.document("BJ").set(
    City("Beijing", None, "China", True, 21500000, ["hebei"]).to_dict()
)
cities_ref.document("SF").set(
    City(
        "San Francisco", "CA", "USA", False, 860000, ["west_coast", "norcal"]
    ).to_dict()
)
cities_ref.document("LA").set(
    City(
        "Los Angeles", "CA", "USA", False, 3900000, ["west_coast", "socal"]
    ).to_dict()
)
cities_ref.document("DC").set(
    City("Washington D.C.", None, "USA", True, 680000, ["east_coast"]).to_dict()
)
cities_ref.document("TOK").set(
    City("Tokyo", None, "Japan", True, 9000000, ["kanto", "honshu"]).to_dict()
)
    snippets.py

    Python

    cities_ref = db.collection("cities")
await cities_ref.document("BJ").set(
    City("Beijing", None, "China", True, 21500000, ["hebei"]).to_dict()
)
await cities_ref.document("SF").set(
    City(
        "San Francisco", "CA", "USA", False, 860000, ["west_coast", "norcal"]
    ).to_dict()
)
await cities_ref.document("LA").set(
    City(
        "Los Angeles", "CA", "USA", False, 3900000, ["west_coast", "socal"]
    ).to_dict()
)
await cities_ref.document("DC").set(
    City("Washington D.C.", None, "USA", True, 680000, ["east_coast"]).to_dict()
)
await cities_ref.document("TOK").set(
    City("Tokyo", None, "Japan", True, 9000000, ["kanto", "honshu"]).to_dict()
)
    snippets.py
    C++
    CollectionReference cities = db->Collection("cities");

cities.Document("SF").Set({
    {"name", FieldValue::String("San Francisco")},
    {"state", FieldValue::String("CA")},
    {"country", FieldValue::String("USA")},
    {"capital", FieldValue::Boolean(false)},
    {"population", FieldValue::Integer(860000)},
    {"regions", FieldValue::Array({FieldValue::String("west_coast"),
                                   FieldValue::String("norcal")})},
});

cities.Document("LA").Set({
    {"name", FieldValue::String("Los Angeles")},
    {"state", FieldValue::String("CA")},
    {"country", FieldValue::String("USA")},
    {"capital", FieldValue::Boolean(false)},
    {"population", FieldValue::Integer(3900000)},
    {"regions", FieldValue::Array({FieldValue::String("west_coast"),
                                   FieldValue::String("socal")})},
});

cities.Document("DC").Set({
    {"name", FieldValue::String("Washington D.C.")},
    {"state", FieldValue::Null()},
    {"country", FieldValue::String("USA")},
    {"capital", FieldValue::Boolean(true)},
    {"population", FieldValue::Integer(680000)},
    {"regions",
     FieldValue::Array({FieldValue::String("east_coast")})},
});

cities.Document("TOK").Set({
    {"name", FieldValue::String("Tokyo")},
    {"state", FieldValue::Null()},
    {"country", FieldValue::String("Japan")},
    {"capital", FieldValue::Boolean(true)},
    {"population", FieldValue::Integer(9000000)},
    {"regions", FieldValue::Array({FieldValue::String("kanto"),
                                   FieldValue::String("honshu")})},
});

cities.Document("BJ").Set({
    {"name", FieldValue::String("Beijing")},
    {"state", FieldValue::Null()},
    {"country", FieldValue::String("China")},
    {"capital", FieldValue::Boolean(true)},
    {"population", FieldValue::Integer(21500000)},
    {"regions", FieldValue::Array({FieldValue::String("jingjinji"),
                                   FieldValue::String("hebei")})},
});
    snippets.cpp
    Node.js
    const citiesRef = db.collection('cities');

await citiesRef.doc('SF').set({
  name: 'San Francisco', state: 'CA', country: 'USA',
  capital: false, population: 860000
});
await citiesRef.doc('LA').set({
  name: 'Los Angeles', state: 'CA', country: 'USA',
  capital: false, population: 3900000
});
await citiesRef.doc('DC').set({
  name: 'Washington, D.C.', state: null, country: 'USA',
  capital: true, population: 680000
});
await citiesRef.doc('TOK').set({
  name: 'Tokyo', state: null, country: 'Japan',
  capital: true, population: 9000000
});
await citiesRef.doc('BJ').set({
  name: 'Beijing', state: null, country: 'China',
  capital: true, population: 21500000
});
    index.js
    Go
    
import (
	"context"

	"cloud.google.com/go/firestore"
)

func prepareRetrieve(ctx context.Context, client *firestore.Client) error {
	cities := []struct {
		id string
		c  City
	}{
		{id: "SF", c: City{Name: "San Francisco", State: "CA", Country: "USA", Capital: false, Population: 860000}},
		{id: "LA", c: City{Name: "Los Angeles", State: "CA", Country: "USA", Capital: false, Population: 3900000}},
		{id: "DC", c: City{Name: "Washington D.C.", Country: "USA", Capital: true, Population: 680000}},
		{id: "TOK", c: City{Name: "Tokyo", Country: "Japan", Capital: true, Population: 9000000}},
		{id: "BJ", c: City{Name: "Beijing", Country: "China", Capital: true, Population: 21500000}},
	}
	for _, c := range cities {
		_, err := client.Collection("cities").Doc(c.id).Set(ctx, c.c)
		if err != nil {
			return err
		}
	}
	return nil
}

    retrieve_data_get_dataset.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $citiesRef = $db->collection('samples/php/cities');
$citiesRef->document('SF')->set([
    'name' => 'San Francisco',
    'state' => 'CA',
    'country' => 'USA',
    'capital' => false,
    'population' => 860000,
    'density' => 18000,
]);
$citiesRef->document('LA')->set([
    'name' => 'Los Angeles',
    'state' => 'CA',
    'country' => 'USA',
    'capital' => false,
    'population' => 3900000,
    'density' => 8000,
]);
$citiesRef->document('DC')->set([
    'name' => 'Washington D.C.',
    'state' => null,
    'country' => 'USA',
    'capital' => true,
    'population' => 680000,
    'density' => 11000,
]);
$citiesRef->document('TOK')->set([
    'name' => 'Tokyo',
    'state' => null,
    'country' => 'Japan',
    'capital' => true,
    'population' => 9000000,
    'density' => 16000,

]);
$citiesRef->document('BJ')->set([
    'name' => 'Beijing',
    'state' => null,
    'country' => 'China',
    'capital' => true,
    'population' => 21500000,
    'density' => 3500,
]);
printf('Added example cities data to the cities collection.' . PHP_EOL);
    data_get_dataset.php
    Einheit
    CollectionReference citiesRef = db.Collection("cities");
citiesRef.Document("SF").SetAsync(new Dictionary<string, object>(){
        { "Name", "San Francisco" },
        { "State", "CA" },
        { "Country", "USA" },
        { "Capital", false },
        { "Population", 860000 }
    }).ContinueWithOnMainThread(task =>
        citiesRef.Document("LA").SetAsync(new Dictionary<string, object>(){
            { "Name", "Los Angeles" },
            { "State", "CA" },
            { "Country", "USA" },
            { "Capital", false },
            { "Population", 3900000 }
        })
).ContinueWithOnMainThread(task =>
    citiesRef.Document("DC").SetAsync(new Dictionary<string, object>(){
            { "Name", "Washington D.C." },
            { "State", null },
            { "Country", "USA" },
            { "Capital", true },
            { "Population", 680000 }
    })
).ContinueWithOnMainThread(task =>
    citiesRef.Document("TOK").SetAsync(new Dictionary<string, object>(){
            { "Name", "Tokyo" },
            { "State", null },
            { "Country", "Japan" },
            { "Capital", true },
            { "Population", 9000000 }
    })
).ContinueWithOnMainThread(task =>
    citiesRef.Document("BJ").SetAsync(new Dictionary<string, object>(){
            { "Name", "Beijing" },
            { "State", null },
            { "Country", "China" },
            { "Capital", true },
            { "Population", 21500000 }
    })
);
    C#
    CollectionReference citiesRef = db.Collection("cities");
await citiesRef.Document("SF").SetAsync(new Dictionary<string, object>(){
    { "Name", "San Francisco" },
    { "State", "CA" },
    { "Country", "USA" },
    { "Capital", false },
    { "Population", 860000 }
});
await citiesRef.Document("LA").SetAsync(new Dictionary<string, object>(){
    { "Name", "Los Angeles" },
    { "State", "CA" },
    { "Country", "USA" },
    { "Capital", false },
    { "Population", 3900000 }
});
await citiesRef.Document("DC").SetAsync(new Dictionary<string, object>(){
    { "Name", "Washington D.C." },
    { "State", null },
    { "Country", "USA" },
    { "Capital", true },
    { "Population", 680000 }
});
await citiesRef.Document("TOK").SetAsync(new Dictionary<string, object>(){
    { "Name", "Tokyo" },
    { "State", null },
    { "Country", "Japan" },
    { "Capital", true },
    { "Population", 9000000 }
});
await citiesRef.Document("BJ").SetAsync(new Dictionary<string, object>(){
    { "Name", "Beijing" },
    { "State", null },
    { "Country", "China" },
    { "Capital", true },
    { "Population", 21500000 }
});
Console.WriteLine("Added example cities data to the cities collection.");
    Program.cs
    Ruby
    cities_ref = firestore.col collection_path
cities_ref.doc("SF").set(
  {
    name:       "San Francisco",
    state:      "CA",
    country:    "USA",
    capital:    false,
    population: 860_000
  }
)
cities_ref.doc("LA").set(
  {
    name:       "Los Angeles",
    state:      "CA",
    country:    "USA",
    capital:    false,
    population: 3_900_000
  }
)
cities_ref.doc("DC").set(
  {
    name:       "Washington D.C.",
    state:      nil,
    country:    "USA",
    capital:    true,
    population: 680_000
  }
)
cities_ref.doc("TOK").set(
  {
    name:       "Tokyo",
    state:      nil,
    country:    "Japan",
    capital:    true,
    population: 9_000_000
  }
)
cities_ref.doc("BJ").set(
  {
    name:       "Beijing",
    state:      nil,
    country:    "China",
    capital:    true,
    population: 21_500_000
  }
)
    get_data.rb

    Dokument abrufen

    Das folgende Beispiel zeigt, wie der Inhalt eines einzelnen Dokuments mithilfe von get() abgerufen werden kann:

    Web

    import { doc, getDoc } from "firebase/firestore";

const docRef = doc(db, "cities", "SF");
const docSnap = await getDoc(docRef);

if (docSnap.exists()) {
  console.log("Document data:", docSnap.data());
} else {
  // docSnap.data() will be undefined in this case
  console.log("No such document!");
}
    get_document.js

    Web

    var docRef = db.collection("cities").doc("SF");

docRef.get().then((doc) => {
    if (doc.exists) {
        console.log("Document data:", doc.data());
    } else {
        // doc.data() will be undefined in this case
        console.log("No such document!");
    }
}).catch((error) => {
    console.log("Error getting document:", error);
});
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    let docRef = db.collection("cities").document("SF")

do {
  let document = try await docRef.getDocument()
  if document.exists {
    let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
    print("Document data: \(dataDescription)")
  } else {
    print("Document does not exist")
  }
} catch {
  print("Error getting document: \(error)")
}
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    FIRDocumentReference *docRef =
    [[self.db collectionWithPath:@"cities"] documentWithPath:@"SF"];
[docRef getDocumentWithCompletion:^(FIRDocumentSnapshot *snapshot, NSError *error) {
  if (snapshot.exists) {
    // Document data may be nil if the document exists but has no keys or values.
    NSLog(@"Document data: %@", snapshot.data);
  } else {
    NSLog(@"Document does not exist");
  }
}];
    ViewController.m

    Kotlin

    val docRef = db.collection("cities").document("SF")
docRef.get()
    .addOnSuccessListener { document ->
        if (document != null) {
            Log.d(TAG, "DocumentSnapshot data: ${document.data}")
        } else {
            Log.d(TAG, "No such document")
        }
    }
    .addOnFailureListener { exception ->
        Log.d(TAG, "get failed with ", exception)
    }
    DocSnippets.kt

    Java

    DocumentReference docRef = db.collection("cities").document("SF");
docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            DocumentSnapshot document = task.getResult();
            if (document.exists()) {
                Log.d(TAG, "DocumentSnapshot data: " + document.getData());
            } else {
                Log.d(TAG, "No such document");
            }
        } else {
            Log.d(TAG, "get failed with ", task.getException());
        }
    }
});
    DocSnippets.java

    Dart

    final docRef = db.collection("cities").doc("SF");
docRef.get().then(
  (DocumentSnapshot doc) {
    final data = doc.data() as Map<String, dynamic>;
    // ...
  },
  onError: (e) => print("Error getting document: $e"),
);
    firestore.dart
    Java
    DocumentReference docRef = db.collection("cities").document("SF");
// asynchronously retrieve the document
ApiFuture<DocumentSnapshot> future = docRef.get();
// ...
// future.get() blocks on response
DocumentSnapshot document = future.get();
if (document.exists()) {
  System.out.println("Document data: " + document.getData());
} else {
  System.out.println("No such document!");
}
    RetrieveDataSnippets.java
    Python
    doc_ref = db.collection("cities").document("SF")

doc = doc_ref.get()
if doc.exists:
    print(f"Document data: {doc.to_dict()}")
else:
    print("No such document!")
    snippets.py

    Python

    doc_ref = db.collection("cities").document("SF")

doc = await doc_ref.get()
if doc.exists:
    print(f"Document data: {doc.to_dict()}")
else:
    print("No such document!")
    snippets.py
    C++
    DocumentReference doc_ref = db->Collection("cities").Document("SF");
doc_ref.Get().OnCompletion([](const Future<DocumentSnapshot>& future) {
  if (future.error() == Error::kErrorOk) {
    const DocumentSnapshot& document = *future.result();
    if (document.exists()) {
      std::cout << "DocumentSnapshot id: " << document.id() << std::endl;
    } else {
      std::cout << "no such document" << std::endl;
    }
  } else {
    std::cout << "Get failed with: " << future.error_message() << std::endl;
  }
});
    snippets.cpp
    Node.js
    const cityRef = db.collection('cities').doc('SF');
const doc = await cityRef.get();
if (!doc.exists) {
  console.log('No such document!');
} else {
  console.log('Document data:', doc.data());
}
    index.js
    Go
    
import (
	"context"
	"fmt"

	"cloud.google.com/go/firestore"
)

func docAsMap(ctx context.Context, client *firestore.Client) (map[string]interface{}, error) {
	dsnap, err := client.Collection("cities").Doc("SF").Get(ctx)
	if err != nil {
		return nil, err
	}
	m := dsnap.Data()
	fmt.Printf("Document data: %#v\n", m)
	return m, nil
}

    retrieve_data_get_as_map.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $docRef = $db->collection('samples/php/cities')->document('SF');
$snapshot = $docRef->snapshot();

if ($snapshot->exists()) {
    printf('Document data:' . PHP_EOL);
    print_r($snapshot->data());
} else {
    printf('Document %s does not exist!' . PHP_EOL, $snapshot->id());
}
    data_get_as_map.php
    Einheit
    DocumentReference docRef = db.Collection("cities").Document("SF");
docRef.GetSnapshotAsync().ContinueWithOnMainThread(task =>
{
  DocumentSnapshot snapshot = task.Result;
  if (snapshot.Exists) {
    Debug.Log(String.Format("Document data for {0} document:", snapshot.Id));
    Dictionary<string, object> city = snapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city) {
      Debug.Log(String.Format("{0}: {1}", pair.Key, pair.Value));
    }
  } else {
    Debug.Log(String.Format("Document {0} does not exist!", snapshot.Id));
  }
});
    C#
    DocumentReference docRef = db.Collection("cities").Document("SF");
DocumentSnapshot snapshot = await docRef.GetSnapshotAsync();
if (snapshot.Exists)
{
    Console.WriteLine("Document data for {0} document:", snapshot.Id);
    Dictionary<string, object> city = snapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city)
    {
        Console.WriteLine("{0}: {1}", pair.Key, pair.Value);
    }
}
else
{
    Console.WriteLine("Document {0} does not exist!", snapshot.Id);
}
    Program.cs
    Ruby
    doc_ref  = firestore.doc "#{collection_path}/SF"
snapshot = doc_ref.get
if snapshot.exists?
  puts "#{snapshot.document_id} data: #{snapshot.data}."
else
  puts "Document #{snapshot.document_id} does not exist!"
end
    get_data.rb

    Quelloptionen

    Bei Plattformen mit Offline-Unterstützung können Sie die Option source festlegen, um zu steuern, wie ein get-Aufruf den Offline-Cache verwendet.

    Standardmäßig versucht ein get-Aufruf, den neuesten Dokument-Snapshot aus Ihrer Datenbank abzurufen. Auf Plattformen mit Offline-Unterstützung verwendet die Clientbibliothek den Offline-Cache, wenn das Netzwerk nicht verfügbar ist oder wenn für die Anfrage eine Zeitüberschreitung auftritt.

    Sie können die Option source in einem get()-Aufruf angeben, um das Standardverhalten zu ändern. Sie können entweder nur aus der Datenbank abrufen und den Offline-Cache ignorieren oder nur aus dem Offline-Cache abrufen. Beispiel:

    Web

    import { doc, getDocFromCache } from "firebase/firestore";

const docRef = doc(db, "cities", "SF");

// Get a document, forcing the SDK to fetch from the offline cache.
try {
  const doc = await getDocFromCache(docRef);

  // Document was found in the cache. If no cached document exists,
  // an error will be returned to the 'catch' block below.
  console.log("Cached document data:", doc.data());
} catch (e) {
  console.log("Error getting cached document:", e);
}
    get_document_options.js

    Web

    var docRef = db.collection("cities").doc("SF");

// Valid options for source are 'server', 'cache', or
// 'default'. See https://firebase.google.com/docs/reference/js/v8/firebase.firestore.GetOptions
// for more information.
var getOptions = {
    source: 'cache'
};

// Get a document, forcing the SDK to fetch from the offline cache.
docRef.get(getOptions).then((doc) => {
    // Document was found in the cache. If no cached document exists,
    // an error will be returned to the 'catch' block below.
    console.log("Cached document data:", doc.data());
}).catch((error) => {
    console.log("Error getting cached document:", error);
});
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    let docRef = db.collection("cities").document("SF")

do {
  // Force the SDK to fetch the document from the cache. Could also specify
  // FirestoreSource.server or FirestoreSource.default.
  let document = try await docRef.getDocument(source: .cache)
  if document.exists {
    let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
    print("Cached document data: \(dataDescription)")
  } else {
    print("Document does not exist in cache")
  }
} catch {
  print("Error getting document: \(error)")
}
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    FIRDocumentReference *docRef =
[[self.db collectionWithPath:@"cities"] documentWithPath:@"SF"];

// Force the SDK to fetch the document from the cache. Could also specify
// FIRFirestoreSourceServer or FIRFirestoreSourceDefault.
[docRef getDocumentWithSource:FIRFirestoreSourceCache
                   completion:^(FIRDocumentSnapshot *snapshot, NSError *error) {
  if (snapshot != NULL) {
    // The document data was found in the cache.
    NSLog(@"Cached document data: %@", snapshot.data);
  } else {
    // The document data was not found in the cache.
    NSLog(@"Document does not exist in cache: %@", error);
  }
}];
    ViewController.m

    Kotlin

    val docRef = db.collection("cities").document("SF")

// Source can be CACHE, SERVER, or DEFAULT.
val source = Source.CACHE

// Get the document, forcing the SDK to use the offline cache
docRef.get(source).addOnCompleteListener { task ->
    if (task.isSuccessful) {
        // Document found in the offline cache
        val document = task.result
        Log.d(TAG, "Cached document data: ${document?.data}")
    } else {
        Log.d(TAG, "Cached get failed: ", task.exception)
    }
}
    DocSnippets.kt

    Java

    DocumentReference docRef = db.collection("cities").document("SF");

// Source can be CACHE, SERVER, or DEFAULT.
Source source = Source.CACHE;

// Get the document, forcing the SDK to use the offline cache
docRef.get(source).addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            // Document found in the offline cache
            DocumentSnapshot document = task.getResult();
            Log.d(TAG, "Cached document data: " + document.getData());
        } else {
            Log.d(TAG, "Cached get failed: ", task.getException());
        }
    }
});
    DocSnippets.java

    Dart

    final docRef = db.collection("cities").doc("SF");

// Source can be CACHE, SERVER, or DEFAULT.
const source = Source.cache;

docRef.get(const GetOptions(source: source)).then(
      (res) => print("Successfully completed"),
      onError: (e) => print("Error completing: $e"),
    );
    firestore.dart
    Java

    Wird im Java SDK nicht unterstützt

    Python

    Wird im Python SDK nicht unterstützt

    C++
    DocumentReference doc_ref = db->Collection("cities").Document("SF");
Source source = Source::kCache;
doc_ref.Get(source).OnCompletion([](const Future<DocumentSnapshot>& future) {
  if (future.error() == Error::kErrorOk) {
    const DocumentSnapshot& document = *future.result();
    if (document.exists()) {
      std::cout << "Cached document id: " << document.id() << std::endl;
    } else {
    }
  } else {
    std::cout << "Cached get failed: " << future.error_message() << std::endl;
  }
});
    snippets.cpp
    Node.js

    Wird im Node.js SDK nicht unterstützt

    Go

    Wird im Go SDK nicht unterstützt

    PHP

    Wird im PHP SDK nicht unterstützt

    Unity

    Wird im Unity SDK nicht unterstützt

    C#

    Wird im C# SDK nicht unterstützt

    Ruby

    Wird im Ruby SDK nicht unterstützt

    Benutzerdefinierte Objekte

    Im vorherigen Beispiel wurde der Inhalt des Dokuments als Karte abgerufen. In einigen Sprachen ist es jedoch häufig praktischer, einen benutzerdefinierten Objekttyp zu verwenden. Unter Daten hinzufügen haben Sie eine City-Klasse festgelegt, mit der Sie die einzelnen Städte definiert haben. Sie können Ihr Dokument wieder in ein City-Objekt umwandeln:

    Wenn Sie benutzerdefinierte Objekte verwenden möchten, müssen Sie eine FirestoreDataConverter-Funktion für Ihre Klasse definieren. Beispiel:

    Web

    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);
    }
};
    city_custom_object.js

    Wenn Sie benutzerdefinierte Objekte verwenden möchten, müssen Sie eine FirestoreDataConverter-Funktion für Ihre Klasse definieren. Beispiel:

    Web

    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);
    }
};
    test.firestore.js

    Rufen Sie für Ihre Lesevorgänge den Datenkonverter auf. Nach der Konvertierung können Sie auf benutzerdefinierte Objektmethoden zugreifen:

    Web

    import { doc, getDoc} from "firebase/firestore"; 

const ref = doc(db, "cities", "LA").withConverter(cityConverter);
const docSnap = await getDoc(ref);
if (docSnap.exists()) {
  // Convert to City object
  const city = docSnap.data();
  // Use a City instance method
  console.log(city.toString());
} else {
  console.log("No such document!");
}
    get_custom_object.js

    Rufen Sie für Ihre Lesevorgänge den Datenkonverter auf. Nach der Konvertierung können Sie auf benutzerdefinierte Objektmethoden zugreifen:

    Web

    db.collection("cities").doc("LA")
  .withConverter(cityConverter)
  .get().then((doc) => {
    if (doc.exists){
      // Convert to City object
      var city = doc.data();
      // Use a City instance method
      console.log(city.toString());
    } else {
      console.log("No such document!");
    }}).catch((error) => {
      console.log("Error getting document:", error);
    });
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar.

    Damit die automatische Serialisierung von Typen in Swift unterstützt wird, muss Ihr Typ dem Codable-Protokoll entsprechen.

    let docRef = db.collection("cities").document("BJ")

do {
  let city = try await docRef.getDocument(as: City.self)
  print("City: \(city)")
} catch {
  print("Error decoding city: \(error)")
}
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar.

    In Objective-C müssen Sie dies manuell tun.

    FIRDocumentReference *docRef =
[[self.db collectionWithPath:@"cities"] documentWithPath:@"BJ"];
[docRef getDocumentWithCompletion:^(FIRDocumentSnapshot *snapshot, NSError *error) {
  FSTCity *city = [[FSTCity alloc] initWithDictionary:snapshot.data];
  if (city != nil) {
    NSLog(@"City: %@", city);
  } else {
    NSLog(@"Document does not exist");
  }
}];
    ViewController.m

    Kotlin

    val docRef = db.collection("cities").document("BJ")
docRef.get().addOnSuccessListener { documentSnapshot ->
    val city = documentSnapshot.toObject<City>()
}
    DocSnippets.kt

    Java

    Wichtig: Jede benutzerdefinierte Klasse muss einen öffentlichen Konstruktor haben, der keine Argumente annimmt. Darüber hinaus muss die Klasse für jedes Attribut einen öffentlichen Getter enthalten. 

    DocumentReference docRef = db.collection("cities").document("BJ");
docRef.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
    @Override
    public void onSuccess(DocumentSnapshot documentSnapshot) {
        City city = documentSnapshot.toObject(City.class);
    }
});
    DocSnippets.java

    Dart

    Wenn Sie benutzerdefinierte Objekte verwenden möchten, müssen Sie Firestore-Datenkonvertierungsfunktionen für Ihre Klasse definieren. Beispiel:

    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,
    };
  }
}
    firestore_add_data_custom_objects_snippet.dart

    Erstellen Sie dann eine Dokumentreferenz mit Ihren Datenkonvertierungsfunktionen. Alle Lesevorgänge, die Sie mit dieser Referenz ausführen, geben Instanzen Ihrer benutzerdefinierten Klasse zurück:

    final ref = db.collection("cities").doc("LA").withConverter(
      fromFirestore: City.fromFirestore,
      toFirestore: (City city, _) => city.toFirestore(),
    );
final docSnap = await ref.get();
final city = docSnap.data(); // Convert to City object
if (city != null) {
  print(city);
} else {
  print("No such document.");
}
    firestore.dart
    Java

    Jede benutzerdefinierte Klasse muss einen öffentlichen Konstruktor haben, der keine Argumente annimmt. Darüber hinaus muss die Klasse für jedes Attribut einen öffentlichen Getter enthalten. 

    DocumentReference docRef = db.collection("cities").document("BJ");
// asynchronously retrieve the document
ApiFuture<DocumentSnapshot> future = docRef.get();
// block on response
DocumentSnapshot document = future.get();
City city = null;
if (document.exists()) {
  // convert document to POJO
  city = document.toObject(City.class);
  System.out.println(city);
} else {
  System.out.println("No such document!");
}
    RetrieveDataSnippets.java
    Python
    doc_ref = db.collection("cities").document("BJ")

doc = doc_ref.get()
city = City.from_dict(doc.to_dict())
print(city)
    snippets.py

    Python

    doc_ref = db.collection("cities").document("BJ")

doc = await doc_ref.get()
city = City.from_dict(doc.to_dict())
print(city)
    snippets.py
    C++
    // This is not yet supported.
    Node.js

    Node.js verwendet JavaScript-Objekte.

    Go
    
import (
	"context"
	"fmt"

	"cloud.google.com/go/firestore"
)

func docAsEntity(ctx context.Context, client *firestore.Client) (*City, error) {
	dsnap, err := client.Collection("cities").Doc("BJ").Get(ctx)
	if err != nil {
		return nil, err
	}
	var c City
	dsnap.DataTo(&c)
	fmt.Printf("Document data: %#v\n", c)
	return &c, nil
}

    retrieve_data_get_as_custom_type.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $docRef = $db->collection('samples/php/cities')->document('SF');
$snapshot = $docRef->snapshot();
$city = City::fromArray($snapshot->data());

if ($snapshot->exists()) {
    printf('Document data:' . PHP_EOL);
    print((string) $city);
} else {
    printf('Document %s does not exist!' . PHP_EOL, $snapshot->id());
}
    data_get_as_custom_type.php
    Einheit
    DocumentReference docRef = db.Collection("cities").Document("BJ");

docRef.GetSnapshotAsync().ContinueWith((task) =>
{
  var snapshot = task.Result;
  if (snapshot.Exists)
  {
    Debug.Log(String.Format("Document data for {0} document:", snapshot.Id));
    City city = snapshot.ConvertTo<City>();
    Debug.Log(String.Format("Name: {0}", city.Name));
    Debug.Log(String.Format("State: {0}", city.State));
    Debug.Log(String.Format("Country: {0}", city.Country));
    Debug.Log(String.Format("Capital: {0}", city.Capital));
    Debug.Log(String.Format("Population: {0}", city.Population));
  }
  else
  {
    Debug.Log(String.Format("Document {0} does not exist!", snapshot.Id));
  }
});
    C#
    DocumentReference docRef = db.Collection("cities").Document("BJ");
DocumentSnapshot snapshot = await docRef.GetSnapshotAsync();
if (snapshot.Exists)
{
    Console.WriteLine("Document data for {0} document:", snapshot.Id);
    City city = snapshot.ConvertTo<City>();
    Console.WriteLine("Name: {0}", city.Name);
    Console.WriteLine("State: {0}", city.State);
    Console.WriteLine("Country: {0}", city.Country);
    Console.WriteLine("Capital: {0}", city.Capital);
    Console.WriteLine("Population: {0}", city.Population);
}
else
{
    Console.WriteLine("Document {0} does not exist!", snapshot.Id);
}
    Program.cs
    Ruby

    Gilt nicht für Ruby

    Mehrere Dokumente aus einer Sammlung abrufen

    Sie können auch mehrere Dokumente mit einer einzigen Anfrage abrufen, indem Sie Dokumente in einer Sammlung abfragen. Sie können beispielsweise where() verwenden, um alle Dokumente abzufragen, die eine bestimmte Bedingung erfüllen, und anschließend get() verwenden, um die Ergebnisse abzurufen:

    Web

    import { collection, query, where, getDocs } from "firebase/firestore";

const q = query(collection(db, "cities"), where("capital", "==", true));

const querySnapshot = await getDocs(q);
querySnapshot.forEach((doc) => {
  // doc.data() is never undefined for query doc snapshots
  console.log(doc.id, " => ", doc.data());
});
    get_multiple.js

    Web

    db.collection("cities").where("capital", "==", true)
    .get()
    .then((querySnapshot) => {
        querySnapshot.forEach((doc) => {
            // doc.data() is never undefined for query doc snapshots
            console.log(doc.id, " => ", doc.data());
        });
    })
    .catch((error) => {
        console.log("Error getting documents: ", error);
    });
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    do {
  let querySnapshot = try await db.collection("cities").whereField("capital", isEqualTo: true)
    .getDocuments()
  for document in querySnapshot.documents {
    print("\(document.documentID) => \(document.data())")
  }
} catch {
  print("Error getting documents: \(error)")
}
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    [[[self.db collectionWithPath:@"cities"] queryWhereField:@"capital" isEqualTo:@(YES)]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
      if (error != nil) {
        NSLog(@"Error getting documents: %@", error);
      } else {
        for (FIRDocumentSnapshot *document in snapshot.documents) {
          NSLog(@"%@ => %@", document.documentID, document.data);
        }
      }
    }];
    ViewController.m

    Kotlin

    db.collection("cities")
    .whereEqualTo("capital", true)
    .get()
    .addOnSuccessListener { documents ->
        for (document in documents) {
            Log.d(TAG, "${document.id} => ${document.data}")
        }
    }
    .addOnFailureListener { exception ->
        Log.w(TAG, "Error getting documents: ", exception)
    }
    DocSnippets.kt

    Java

    db.collection("cities")
        .whereEqualTo("capital", true)
        .get()
        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, document.getId() + " => " + document.getData());
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.getException());
                }
            }
        });
    DocSnippets.java

    Dart

    db.collection("cities").where("capital", isEqualTo: true).get().then(
  (querySnapshot) {
    print("Successfully completed");
    for (var docSnapshot in querySnapshot.docs) {
      print('${docSnapshot.id} => ${docSnapshot.data()}');
    }
  },
  onError: (e) => print("Error completing: $e"),
);
    firestore.dart
    Java
    // asynchronously retrieve multiple documents
ApiFuture<QuerySnapshot> future = db.collection("cities").whereEqualTo("capital", true).get();
// future.get() blocks on response
List<QueryDocumentSnapshot> documents = future.get().getDocuments();
for (DocumentSnapshot document : documents) {
  System.out.println(document.getId() + " => " + document.toObject(City.class));
}
    RetrieveDataSnippets.java
    Python
    # Note: Use of CollectionRef stream() is prefered to get()
docs = (
    db.collection("cities")
    .where(filter=FieldFilter("capital", "==", True))
    .stream()
)

for doc in docs:
    print(f"{doc.id} => {doc.to_dict()}")
    snippets.py

    Python

    # Note: Use of CollectionRef stream() is prefered to get()
docs = (
    db.collection("cities")
    .where(filter=FieldFilter("capital", "==", True))
    .stream()
)

async for doc in docs:
    print(f"{doc.id} => {doc.to_dict()}")
    snippets.py
    C++
    db->Collection("cities")
    .WhereEqualTo("capital", FieldValue::Boolean(true))
    .Get()
    .OnCompletion([](const Future<QuerySnapshot>& future) {
      if (future.error() == Error::kErrorOk) {
        for (const DocumentSnapshot& document :
             future.result()->documents()) {
          std::cout << document << std::endl;
        }
      } else {
        std::cout << "Error getting documents: " << future.error_message()
                  << std::endl;
      }
    });
    snippets.cpp
    Node.js
    const citiesRef = db.collection('cities');
const snapshot = await citiesRef.where('capital', '==', true).get();
if (snapshot.empty) {
  console.log('No matching documents.');
  return;
}  

snapshot.forEach(doc => {
  console.log(doc.id, '=>', doc.data());
});
    index.js
    Go
    
import (
	"context"
	"fmt"

	"cloud.google.com/go/firestore"
	"google.golang.org/api/iterator"
)

func multipleDocs(ctx context.Context, client *firestore.Client) error {
	fmt.Println("All capital cities:")
	iter := client.Collection("cities").Where("capital", "==", true).Documents(ctx)
	for {
		doc, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return err
		}
		fmt.Println(doc.Data())
	}
	return nil
}

    retrieve_data_query.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $citiesRef = $db->collection('samples/php/cities');
$query = $citiesRef->where('capital', '=', true);
$documents = $query->documents();
foreach ($documents as $document) {
    if ($document->exists()) {
        printf('Document data for document %s:' . PHP_EOL, $document->id());
        print_r($document->data());
        printf(PHP_EOL);
    } else {
        printf('Document %s does not exist!' . PHP_EOL, $document->id());
    }
}
    data_query.php
    Einheit
    Query capitalQuery = db.Collection("cities").WhereEqualTo("Capital", true);
capitalQuery.GetSnapshotAsync().ContinueWithOnMainThread(task => {
  QuerySnapshot capitalQuerySnapshot = task.Result;
  foreach (DocumentSnapshot documentSnapshot in capitalQuerySnapshot.Documents) {
    Debug.Log(String.Format("Document data for {0} document:", documentSnapshot.Id));
    Dictionary<string, object> city = documentSnapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city) {
      Debug.Log(String.Format("{0}: {1}", pair.Key, pair.Value));
    }

    // Newline to separate entries
    Debug.Log("");
  };
});
    C#
    Query capitalQuery = db.Collection("cities").WhereEqualTo("Capital", true);
QuerySnapshot capitalQuerySnapshot = await capitalQuery.GetSnapshotAsync();
foreach (DocumentSnapshot documentSnapshot in capitalQuerySnapshot.Documents)
{
    Console.WriteLine("Document data for {0} document:", documentSnapshot.Id);
    Dictionary<string, object> city = documentSnapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city)
    {
        Console.WriteLine("{0}: {1}", pair.Key, pair.Value);
    }
    Console.WriteLine("");
}
    Program.cs
    Ruby
    cities_ref = firestore.col collection_path

query = cities_ref.where "capital", "=", true

query.get do |city|
  puts "#{city.document_id} data: #{city.data}."
end
    get_data.rb

    Standardmäßig ruft Cloud Firestore alle Dokumente, die die Abfrage erfüllen, in aufsteigender Reihenfolge nach Dokument-ID ab. Sie können aber auch die zurückgegebenen Daten sortieren und beschränken.

    Alle Dokumente in einer Sammlung abrufen

    Darüber hinaus können Sie alle Dokumente in einer Sammlung abrufen, indem Sie den Filter where() ganz weglassen:

    Web

    import { collection, getDocs } from "firebase/firestore";

const querySnapshot = await getDocs(collection(db, "cities"));
querySnapshot.forEach((doc) => {
  // doc.data() is never undefined for query doc snapshots
  console.log(doc.id, " => ", doc.data());
});
    get_multiple_all.js

    Web

    db.collection("cities").get().then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
        // doc.data() is never undefined for query doc snapshots
        console.log(doc.id, " => ", doc.data());
    });
});
    test.firestore.js
    Swift
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    do {
  let querySnapshot = try await db.collection("cities").getDocuments()
  for document in querySnapshot.documents {
    print("\(document.documentID) => \(document.data())")
  }
} catch {
  print("Error getting documents: \(error)")
}
    ViewController.swift
    Objective-C
    Hinweis: Dieses Produkt nicht ist auf WatchOS- und App Clip-Zielen verfügbar. 
    [[self.db collectionWithPath:@"cities"]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
      if (error != nil) {
        NSLog(@"Error getting documents: %@", error);
      } else {
        for (FIRDocumentSnapshot *document in snapshot.documents) {
          NSLog(@"%@ => %@", document.documentID, document.data);
        }
      }
    }];
    ViewController.m

    Kotlin

    db.collection("cities")
    .get()
    .addOnSuccessListener { result ->
        for (document in result) {
            Log.d(TAG, "${document.id} => ${document.data}")
        }
    }
    .addOnFailureListener { exception ->
        Log.d(TAG, "Error getting documents: ", exception)
    }
    DocSnippets.kt

    Java

    db.collection("cities")
        .get()
        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, document.getId() + " => " + document.getData());
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.getException());
                }
            }
        });
    DocSnippets.java

    Dart

    db.collection("cities").get().then(
  (querySnapshot) {
    print("Successfully completed");
    for (var docSnapshot in querySnapshot.docs) {
      print('${docSnapshot.id} => ${docSnapshot.data()}');
    }
  },
  onError: (e) => print("Error completing: $e"),
);
    firestore.dart
    Java
    // asynchronously retrieve all documents
ApiFuture<QuerySnapshot> future = db.collection("cities").get();
// future.get() blocks on response
List<QueryDocumentSnapshot> documents = future.get().getDocuments();
for (QueryDocumentSnapshot document : documents) {
  System.out.println(document.getId() + " => " + document.toObject(City.class));
}
    RetrieveDataSnippets.java
    Python
    docs = db.collection("cities").stream()

for doc in docs:
    print(f"{doc.id} => {doc.to_dict()}")
    snippets.py

    Python

    docs = db.collection("cities").stream()

async for doc in docs:
    print(f"{doc.id} => {doc.to_dict()}")
    snippets.py
    C++
    db->Collection("cities").Get().OnCompletion(
    [](const Future<QuerySnapshot>& future) {
      if (future.error() == Error::kErrorOk) {
        for (const DocumentSnapshot& document :
             future.result()->documents()) {
          std::cout << document << std::endl;
        }
      } else {
        std::cout << "Error getting documents: " << future.error_message()
                  << std::endl;
      }
    });
    snippets.cpp
    Node.js
    const citiesRef = db.collection('cities');
const snapshot = await citiesRef.get();
snapshot.forEach(doc => {
  console.log(doc.id, '=>', doc.data());
});
    index.js
    Go
    
import (
	"context"
	"fmt"

	"cloud.google.com/go/firestore"
	"google.golang.org/api/iterator"
)

func allDocs(ctx context.Context, client *firestore.Client) error {
	fmt.Println("All cities:")
	iter := client.Collection("cities").Documents(ctx)
	defer iter.Stop()
	for {
		doc, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return err
		}
		fmt.Println(doc.Data())
	}
	return nil
}

    retrieve_data_get_all_documents.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $citiesRef = $db->collection('samples/php/cities');
$documents = $citiesRef->documents();
foreach ($documents as $document) {
    if ($document->exists()) {
        printf('Document data for document %s:' . PHP_EOL, $document->id());
        print_r($document->data());
        printf(PHP_EOL);
    } else {
        printf('Document %s does not exist!' . PHP_EOL, $document->id());
    }
}
    data_get_all_documents.php
    Einheit
    Query allCitiesQuery = db.Collection("cities");
allCitiesQuery.GetSnapshotAsync().ContinueWithOnMainThread(task =>
{
  QuerySnapshot allCitiesQuerySnapshot = task.Result;
  foreach (DocumentSnapshot documentSnapshot in allCitiesQuerySnapshot.Documents)
  {
    Debug.Log(String.Format("Document data for {0} document:", documentSnapshot.Id));
    Dictionary<string, object> city = documentSnapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city)
    {
      Debug.Log(String.Format("{0}: {1}", pair.Key, pair.Value));
    }

    // Newline to separate entries
    Debug.Log("");
  }
});
    C#
    Query allCitiesQuery = db.Collection("cities");
QuerySnapshot allCitiesQuerySnapshot = await allCitiesQuery.GetSnapshotAsync();
foreach (DocumentSnapshot documentSnapshot in allCitiesQuerySnapshot.Documents)
{
    Console.WriteLine("Document data for {0} document:", documentSnapshot.Id);
    Dictionary<string, object> city = documentSnapshot.ToDictionary();
    foreach (KeyValuePair<string, object> pair in city)
    {
        Console.WriteLine("{0}: {1}", pair.Key, pair.Value);
    }
    Console.WriteLine("");
}
    Program.cs
    Ruby
    cities_ref = firestore.col collection_path
cities_ref.get do |city|
  puts "#{city.document_id} data: #{city.data}."
end
    get_data.rb

    Alle Dokumente in einer untergeordneten Sammlung abrufen

    Wenn Sie alle Dokumente aus einer Untersammlung abrufen möchten, erstellen Sie eine Referenz mit dem vollständigen Pfad zu dieser Untersammlung:

    Web

    const { collection, getDocs } = require("firebase/firestore");
// Query a reference to a subcollection
const querySnapshot = await getDocs(collection(db, "cities", "SF", "landmarks"));
querySnapshot.forEach((doc) => {
  // doc.data() is never undefined for query doc snapshots
  console.log(doc.id, " => ", doc.data());
});
    test.firestore.js

    Web

    // Snippet not available
    Swift
    do {
  let querySnapshot = try await db.collection("cities/SF/landmarks").getDocuments()
  for document in querySnapshot.documents {
    print("\(document.documentID) => \(document.data())")
  }
} catch {
  print("Error getting documents: \(error)")
}
    ViewController.swift
    Objective-C
    [[self.db collectionWithPath:@"cities/SF/landmarks"]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
      if (error != nil) {
        NSLog(@"Error getting documents: %@", error);
      } else {
        for (FIRDocumentSnapshot *document in snapshot.documents) {
          NSLog(@"%@ => %@", document.documentID, document.data);
        }
      }
    }];
    ViewController.m

    Kotlin

    db.collection("cities")
    .document("SF")
    .collection("landmarks")
    .get()
    .addOnSuccessListener { result ->
        for (document in result) {
            Log.d(TAG, "${document.id} => ${document.data}")
        }
    }
    .addOnFailureListener { exception ->
        Log.d(TAG, "Error getting documents: ", exception)
    }
    DocSnippets.kt

    Java

    db.collection("cities")
        .document("SF")
        .collection("landmarks")
        .get()
        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, document.getId() + " => " + document.getData());
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.getException());
                }
            }
        });
    DocSnippets.java

    Dart

    db.collection("cities").doc("SF").collection("landmarks").get().then(
  (querySnapshot) {
    print("Successfully completed");
    for (var docSnapshot in querySnapshot.docs) {
      print('${docSnapshot.id} => ${docSnapshot.data()}');
    }
  },
  onError: (e) => print("Error completing: $e"),
);
    firestore.dart
    Java
    // Snippet not available
    Python
    // Snippet not available

    Python

    // Snippet not available
    C++
    // Snippet not available
    Node.js
    // Snippet not available
    Go
    // Snippet not available
    PHP
    // Snippet not available
    Unity
    // Snippet not available
    C#
    // Snippet not available
    Ruby
    // Snippet not available

    Mehrere Dokumente aus einer Sammlungsgruppe abrufen

    Eine Sammlungsgruppe umfasst alle Sammlungen mit derselben ID. Wenn beispielsweise jedes Dokument in Ihrer Sammlung cities eine Untersammlung namens landmarks hat, gehören all diese landmarks-Untersammlungen zur selben Sammlungsgruppe. Standardmäßig rufen Abfragen Ergebnisse aus einer einzelnen Sammlung in Ihrer Datenbank ab. Verwenden Sie eine Sammlungsgruppenabfrage, um Ergebnisse aus einer Sammlungsgruppe abzurufen, statt aus einer einzelnen Sammlung.

    Untergeordnete Sammlungen eines Dokuments auflisten

    Die Methode listCollections() der Cloud Firestore-Server-Clientbibliotheken listet alle Untersammlungen einer Dokumentreferenz auf.

    Das Abrufen einer Liste von Sammlungen ist mit den Mobil-/Web-Clientbibliotheken nicht möglich. Sie sollten nach Sammlungsnamen nur im Rahmen von Verwaltungsaufgaben in vertrauenswürdigen Serverumgebungen suchen. Wenn Sie diese Funktion in den Mobil-/Web-Clientbibliotheken benötigen, sollten Sie Ihre Daten so umstrukturieren, dass die Namen der Untersammlungen vorhersehbar sind.

    Web

    Nicht verfügbar in der Web-Clientbibliothek

    Swift

    Nicht verfügbar in der Swift-Clientbibliothek.

    Objective-C

    Nicht verfügbar in der Objective-C-Clientbibliothek

    Kotlin

    Nicht verfügbar in der Android-Clientbibliothek

    Java

    Nicht verfügbar in der Android-Clientbibliothek

    Dart

    Nicht verfügbar in der Flutter-Clientbibliothek.

    Java
    Iterable<CollectionReference> collections =
    db.collection("cities").document("SF").listCollections();

for (CollectionReference collRef : collections) {
  System.out.println("Found subcollection with id: " + collRef.getId());
}
    RetrieveDataSnippets.java
    Python
    city_ref = db.collection("cities").document("SF")
collections = city_ref.collections()
for collection in collections:
    for doc in collection.stream():
        print(f"{doc.id} => {doc.to_dict()}")
    snippets.py

    Python

    collections = db.collection("cities").document("SF").collections()
async for collection in collections:
    async for doc in collection.stream():
        print(f"{doc.id} => {doc.to_dict()}")
    snippets.py
    C++

    Nicht verfügbar in der C++-Clientbibliothek

    Node.js
    const sfRef = db.collection('cities').doc('SF');
const collections = await sfRef.listCollections();
collections.forEach(collection => {
  console.log('Found subcollection with id:', collection.id);
});
    index.js
    Go
    
import (
	"context"
	"fmt"

	"cloud.google.com/go/firestore"
	"google.golang.org/api/iterator"
)

func getCollections(ctx context.Context, client *firestore.Client) error {
	iter := client.Collection("cities").Doc("SF").Collections(ctx)
	for {
		collRef, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return err
		}
		fmt.Printf("Found collection with id: %s\n", collRef.ID)
	}
	return nil
}

    retrieve_data_get_sub_collections.go
    PHP

    PHP

    Weitere Informationen zum Installieren und Erstellen eines Cloud Firestore-Clients finden Sie unter Cloud Firestore-Clientbibliotheken. 

    $cityRef = $db->collection('samples/php/cities')->document('SF');
$collections = $cityRef->collections();
foreach ($collections as $collection) {
    printf('Found subcollection with id: %s' . PHP_EOL, $collection->id());
}
    data_get_sub_collections.php
    Einheit
    // This is not yet supported in the Unity SDK.
    C#
    DocumentReference cityRef = db.Collection("cities").Document("SF");
IAsyncEnumerable<CollectionReference> subcollections = cityRef.ListCollectionsAsync();
IAsyncEnumerator<CollectionReference> subcollectionsEnumerator = subcollections.GetAsyncEnumerator(default);
while (await subcollectionsEnumerator.MoveNextAsync())
{
    CollectionReference subcollectionRef = subcollectionsEnumerator.Current;
    Console.WriteLine("Found subcollection with ID: {0}", subcollectionRef.Id);
}
    Program.cs
    Ruby
    city_ref = firestore.doc "#{collection_path}/SF"
city_ref.cols do |col|
  puts col.collection_id
end
    get_data.rb

    Weitere Informationen zu verschiedenen Arten von Abfragen

    Weitere Informationen zu Fehlercodes und zur Behebung von Latenzproblemen beim Abrufen von Daten finden Sie auf der Fehlerbehebungsseite.