Há duas maneiras de recuperar dados armazenados no Cloud Firestore. Qualquer um desses métodos pode ser usado com documentos, coleções de documentos ou os resultados de consultas:
- Chame um método para receber os dados.
- Defina um listener para receber eventos de mudança de dados.
Quando você configura um listener, o Cloud Firestore envia para ele um snapshot inicial dos dados e, em seguida, outro snapshot cada vez que o documento é alterado.
.Dados de exemplo
Para começar, escreva alguns dados sobre cidades para demonstrarmos diversas formas de leitura:
Web version 9
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"] });
Web version 8
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"] });
Swift
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"] ])
Objective-C
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"] }];
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);
Kotlin+KTX
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)
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);
Java
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}\ )' )
cities_ref = db.collection(u'cities') cities_ref.document(u'BJ').set( City(u'Beijing', None, u'China', True, 21500000, [u'hebei']).to_dict()) cities_ref.document(u'SF').set( City(u'San Francisco', u'CA', u'USA', False, 860000, [u'west_coast', u'norcal']).to_dict()) cities_ref.document(u'LA').set( City(u'Los Angeles', u'CA', u'USA', False, 3900000, [u'west_coast', u'socal']).to_dict()) cities_ref.document(u'DC').set( City(u'Washington D.C.', None, u'USA', True, 680000, [u'east_coast']).to_dict()) cities_ref.document(u'TOK').set( City(u'Tokyo', None, u'Japan', True, 9000000, [u'kanto', u'honshu']).to_dict())
Python
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")})}, });
Node.js
Go
PHP
$citiesRef = $db->collection('samples/php/cities'); $citiesRef->document('SF')->set([ 'name' => 'San Francisco', 'state' => 'CA', 'country' => 'USA', 'capital' => false, 'population' => 860000 ]); $citiesRef->document('LA')->set([ 'name' => 'Los Angeles', 'state' => 'CA', 'country' => 'USA', 'capital' => false, 'population' => 3900000 ]); $citiesRef->document('DC')->set([ 'name' => 'Washington D.C.', 'state' => null, 'country' => 'USA', 'capital' => true, 'population' => 680000 ]); $citiesRef->document('TOK')->set([ 'name' => 'Tokyo', 'state' => null, 'country' => 'Japan', 'capital' => true, 'population' => 9000000 ]); $citiesRef->document('BJ')->set([ 'name' => 'Beijing', 'state' => null, 'country' => 'China', 'capital' => true, 'population' => 21500000 ]); printf('Added example cities data to the cities collection.' . PHP_EOL);
Unity
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.");
Ruby
Receber um documento
No exemplo a seguir, mostramos como recuperar o conteúdo de um único documento
usando get()
:
Web version 9
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 { // doc.data() will be undefined in this case console.log("No such document!"); }
Web version 8
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); });
Swift
let docRef = db.collection("cities").document("SF") docRef.getDocument { (document, error) in if let document = document, document.exists { let dataDescription = document.data().map(String.init(describing:)) ?? "nil" print("Document data: \(dataDescription)") } else { print("Document does not exist") } }
Objective-C
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"); } }];
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()); } } });
Kotlin+KTX
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) }
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"), );
Java
Python
Python
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; } });
Node.js
Go
PHP
$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()); }
Unity
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); }
Ruby
Opções de origem
Para plataformas com suporte off-line, defina a opção source
para controlar
como uma chamada get
usa o cache off-line.
Por padrão, uma chamada get
tentará buscar o snapshot do documento mais recente do
seu banco de dados. Nas plataformas com suporte off-line, a biblioteca de cliente usará
o cache off-line se a rede estiver indisponível ou se a solicitação expirar.
É possível especificar a opção source
em uma chamada get()
para alterar
o comportamento padrão. É possível buscar apenas no banco de dados e ignorar
o cache off-line ou buscar somente no cache off-line. Exemplo:
Web version 9
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); }
Web version 8
var docRef = db.collection("cities").doc("SF"); // Valid options for source are 'server', 'cache', or // 'default'. See https://firebase.google.com/docs/reference/js/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); });
Swift
let docRef = db.collection("cities").document("SF") // Force the SDK to fetch the document from the cache. Could also specify // FirestoreSource.server or FirestoreSource.default. docRef.getDocument(source: .cache) { (document, error) in if let document = document { let dataDescription = document.data().map(String.init(describing:)) ?? "nil" print("Cached document data: \(dataDescription)") } else { print("Document does not exist in cache") } }
Objective-C
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); } }];
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()); } } });
Kotlin+KTX
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) } }
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"), );
Java
Não é compatível com o SDK do Java.
Python
Não é compatível com o SDK do Python.
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; } });
Node.js
Não é compatível com o SDK do Node.js.
Go
Não é compatível com o SDK do Go.
PHP
Não é compatível com o SDK do PHP.
Unity
Não é compatível com o SDK do Unity.
C#
Não é compatível com o SDK do C#.
Ruby
Não é compatível com o SDK do Ruby.
Objetos personalizados
O exemplo anterior recuperou o conteúdo do
documento como um mapa. No entanto, muitas vezes é mais conveniente usar um tipo de objeto personalizado
em algumas linguagens. Em Adicionar dados, você definiu uma classe City
que usou para definir cada cidade. É possível transformar seu documento em um objeto
City
:
Para usar objetos personalizados, defina uma função FirestoreDataConverter para sua classe. Exemplo:
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); } };
Para usar objetos personalizados, defina uma função FirestoreDataConverter para sua classe. Exemplo:
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); } };
Chame seu conversor de dados com suas operações de leitura. Após a conversão, você pode acessar métodos de objeto personalizados:
Web version 9
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!"); }
Chame seu conversor de dados com suas operações de leitura. Após a conversão, você pode acessar métodos de objeto personalizados:
Web version 8
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); });
Swift
Para oferecer suporte à serialização automática de tipos no Swift, seu tipo precisa estar em conformidade com o
protocolo Codable,
e você precisa incluir pod 'FirebaseFirestoreSwift'
como uma dependência
do projeto.
let docRef = db.collection("cities").document("BJ") docRef.getDocument(as: City.self) { result in // The Result type encapsulates deserialization errors or // successful deserialization, and can be handled as follows: // // Result // /\ // Error City switch result { case .success(let city): // A `City` value was successfully initialized from the DocumentSnapshot. print("City: \(city)") case .failure(let error): // A `City` value could not be initialized from the DocumentSnapshot. print("Error decoding city: \(error)") } }
Objective-C
Em Objective-C, você precisa fazer isso manualmente.
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"); } }];
Java
Importante: cada classe personalizada precisa ter um construtor público sem argumentos. Além disso, a classe precisa incluir um getter público para cada propriedade.
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); } });
Kotlin+KTX
val docRef = db.collection("cities").document("BJ") docRef.get().addOnSuccessListener { documentSnapshot -> val city = documentSnapshot.toObject<City>() }
Dart
Para usar objetos personalizados, você precisa definir as funções de conversão de dados do Firestore para sua classe. Exemplo:
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, }; } }
Em seguida, crie uma referência de documento com suas funções de conversão de dados. Qualquer operação de leitura que você executar usando essa referência retornará instâncias da sua classe personalizada:
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."); }
Java
Cada classe personalizada deve ter um construtor público sem argumentos. Além disso, a classe precisa incluir um getter público para cada propriedade.
Python
Python
C++
// This is not yet supported.
Node.js
O Node.js usa objetos JavaScript.
Go
PHP
Não aplicável para PHP.
Unity
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); }
Ruby
Não aplicável para Ruby.
Obter vários documentos de uma coleção
Também é possível recuperar vários documentos com uma solicitação, basta consultar os documentos
em uma coleção. Por exemplo, use where()
para consultar todos os
documentos que atendam a uma determinada condição e use get()
para recuperar os
resultados:
Web version 9
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()); });
Web version 8
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); });
Swift
db.collection("cities").whereField("capital", isEqualTo: true) .getDocuments() { (querySnapshot, err) in if let err = err { print("Error getting documents: \(err)") } else { for document in querySnapshot!.documents { print("\(document.documentID) => \(document.data())") } } }
Objective-C
[[[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); } } }];
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()); } } });
Kotlin+KTX
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) }
Dart
db.collection("cities").where("capital", isEqualTo: true).get().then( (res) => print("Successfully completed"), onError: (e) => print("Error completing: $e"), );
Java
Python
Python
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; } });
Node.js
Go
PHP
$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()); } }
Unity
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(""); }
Ruby
Por padrão, o Cloud Firestore recupera todos os documentos que atendem à consulta em ordem crescente por ID. No entanto, é possível ordenar e limitar os dados retornados.
Recuperar todos os documentos em uma coleção
Além disso, é possível recuperar todos os documentos de uma coleção, basta omitir o filtro
where()
completamente:
Web version 9
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()); });
Web version 8
db.collection("cities").get().then((querySnapshot) => { querySnapshot.forEach((doc) => { // doc.data() is never undefined for query doc snapshots console.log(doc.id, " => ", doc.data()); }); });
Swift
db.collection("cities").getDocuments() { (querySnapshot, err) in if let err = err { print("Error getting documents: \(err)") } else { for document in querySnapshot!.documents { print("\(document.documentID) => \(document.data())") } } }
Objective-C
[[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); } } }];
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()); } } });
Kotlin+KTX
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) }
Dart
db.collection("cities").get().then( (res) => print("Successfully completed"), onError: (e) => print("Error completing: $e"), );
Java
Python
Python
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; } });
Node.js
Go
PHP
$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()); } }
Unity
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(""); }
Ruby
Reunir vários documentos de um grupo de coleções
Um grupo de coleções é composto de todos os conjuntos com o mesmo ID. Por exemplo, se
cada documento da coleção cities
tiver uma subcoleção chamada
landmarks
, todas as subcoleções de landmarks
pertencerão ao mesmo grupo. Por padrão, as consultas recuperam resultados de uma única coleção no seu
banco de dados. Use uma consulta de grupo de coleções para recuperar resultados de um
grupo, em vez de uma única coleção.
Listar as subcoleções de um documento
O método listCollections()
das bibliotecas de cliente do servidor do Cloud Firestore
lista todas as subcoleções de uma referência de documento.
Não é possível recuperar uma lista de coleções com as bibliotecas de cliente da Web/para dispositivos móveis. Procure nomes de coleções somente como parte de tarefas administrativas em ambientes de servidor confiáveis. Se você julgar que precisa desse recurso nas bibliotecas de clientes da Web/para dispositivos móveis, pense em reestruturar seus dados para que os nomes de subcoleções sejam previsíveis.
Web
Não disponível na biblioteca de cliente da Web.
Swift
Não disponível na biblioteca de cliente do Swift.
Objective-C
Não disponível na biblioteca de cliente do Objective-C.
Java
Não disponível na biblioteca de cliente do Android.
Kotlin+KTX
Não disponível na biblioteca de cliente do Android.
Dart
Não disponível na biblioteca de cliente do Flutter.
Java
Python
Python
C++
Não disponível na biblioteca de cliente do C++
Node.js
Go
PHP
$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()); }
Unity
// 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); }
Ruby
Saiba mais sobre os diferentes tipos de consultas.