Cloud Firestore offre potenti funzionalità di query per specificare quali documenti desideri recuperare da una raccolta o da un gruppo di raccolte. Queste query possono essere utilizzate anche con get()
o addSnapshotListener()
, come descritto in Ottenere dati e Ottenere aggiornamenti in tempo reale .
Dati di esempio
Per iniziare, scrivi alcuni dati sulle città in modo che possiamo esaminare diversi modi per rileggerli:
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"] });
Rapido
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"] ])
Obiettivo-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"] }];
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)
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);
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);
Giava
Pitone
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
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("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() )
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
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); citiesRef.Document("SF").SetAsync(new Dictionary<string, object>(){ { "Name", "San Francisco" }, { "State", "CA" }, { "Country", "USA" }, { "Capital", false }, { "Population", 860000 }, { "Regions", new ArrayList{"west_coast", "norcal"} } }); citiesRef.Document("LA").SetAsync(new Dictionary<string, object>(){ { "Name", "Los Angeles" }, { "State", "CA" }, { "Country", "USA" }, { "Capital", false }, { "Population", 3900000 }, { "Regions", new ArrayList{"west_coast", "socal"} } }); citiesRef.Document("DC").SetAsync(new Dictionary<string, object>(){ { "Name", "Washington D.C." }, { "State", null }, { "Country", "USA" }, { "Capital", true }, { "Population", 680000 }, { "Regions", new ArrayList{"east_coast"} } }); citiesRef.Document("TOK").SetAsync(new Dictionary<string, object>(){ { "Name", "Tokyo" }, { "State", null }, { "Country", "Japan" }, { "Capital", true }, { "Population", 9000000 }, { "Regions", new ArrayList{"kanto", "honshu"} } }); citiesRef.Document("BJ").SetAsync(new Dictionary<string, object>(){ { "Name", "Beijing" }, { "State", null }, { "Country", "China" }, { "Capital", true }, { "Population", 21500000 }, { "Regions", new ArrayList{"jingjinji", "hebei"} } });
C#
Rubino
Domande semplici
La seguente query restituisce tutte le città con stato CA
:
Web version 9
// Create a reference to the cities collection import { collection, query, where } from "firebase/firestore"; const citiesRef = collection(db, "cities"); // Create a query against the collection. const q = query(citiesRef, where("state", "==", "CA"));
Web version 8
// Create a reference to the cities collection var citiesRef = db.collection("cities"); // Create a query against the collection. var query = citiesRef.where("state", "==", "CA");
Rapido
// Create a reference to the cities collection let citiesRef = db.collection("cities") // Create a query against the collection. let query = citiesRef.whereField("state", isEqualTo: "CA")
Obiettivo-C
// Create a reference to the cities collection FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"]; // Create a query against the collection. FIRQuery *query = [citiesRef queryWhereField:@"state" isEqualTo:@"CA"];
Kotlin+KTX
// Create a reference to the cities collection val citiesRef = db.collection("cities") // Create a query against the collection. val query = citiesRef.whereEqualTo("state", "CA")
Java
// Create a reference to the cities collection CollectionReference citiesRef = db.collection("cities"); // Create a query against the collection. Query query = citiesRef.whereEqualTo("state", "CA");
Dart
// Create a reference to the cities collection final citiesRef = db.collection("cities"); // Create a query against the collection. final query = citiesRef.where("state", isEqualTo: "CA");
Giava
Pitone
Python
C++
CollectionReference cities_ref = db->Collection("cities"); // Create a query against the collection. Query query_ca = cities_ref.WhereEqualTo("state", FieldValue::String("CA"));
Node.js
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); Query query = citiesRef.WhereEqualTo("State", "CA"); query.GetSnapshotAsync().ContinueWithOnMainThread((querySnapshotTask) => { foreach (DocumentSnapshot documentSnapshot in querySnapshotTask.Result.Documents) { Debug.Log(String.Format("Document {0} returned by query State=CA", documentSnapshot.Id)); } });
C#
Rubino
La seguente query restituisce tutte le capitali:
Web version 9
import { collection, query, where } from "firebase/firestore"; const citiesRef = collection(db, "cities"); const q = query(citiesRef, where("capital", "==", true));
Web version 8
var citiesRef = db.collection("cities"); var query = citiesRef.where("capital", "==", true);
Rapido
let capitalCities = db.collection("cities").whereField("capital", isEqualTo: true)
Obiettivo-C
FIRQuery *capitalCities = [[self.db collectionWithPath:@"cities"] queryWhereField:@"capital" isEqualTo:@YES];
Kotlin+KTX
val capitalCities = db.collection("cities").whereEqualTo("capital", true)
Java
Query capitalCities = db.collection("cities").whereEqualTo("capital", true);
Dart
final capitalcities = db.collection("cities").where("capital", isEqualTo: true);
Giava
Pitone
Python
C++
Query capital_cities = db->Collection("cities").WhereEqualTo( "capital", FieldValue::Boolean(true));
Node.js
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); Query query = citiesRef.WhereEqualTo("Capital", true); query.GetSnapshotAsync().ContinueWithOnMainThread((querySnapshotTask) => { foreach (DocumentSnapshot documentSnapshot in querySnapshotTask.Result.Documents) { Debug.Log(String.Format("Document {0} returned by query Capital=true", documentSnapshot.Id)); } });
C#
Rubino
Eseguire una query
Dopo aver creato un oggetto query, utilizzare la funzione get()
per recuperare i risultati:
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); });
Rapido
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())") } } }
Obiettivo-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); } } }];
Kotlin+KTX
db.collection("cities") .whereEqualTo("capital", true) .get() .addOnSuccessListener { documents -> for (document in documents) { Log.d(TAG, "${document.id} => ${document.data}") } } .addOnFailureListener { exception -> Log.w(TAG, "Error getting documents: ", exception) }
Java
db.collection("cities") .whereEqualTo("capital", true) .get() .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() { @Override public void onComplete(@NonNull Task<QuerySnapshot> task) { if (task.isSuccessful()) { for (QueryDocumentSnapshot document : task.getResult()) { Log.d(TAG, document.getId() + " => " + document.getData()); } } else { Log.d(TAG, "Error getting documents: ", task.getException()); } } });
Dart
db.collection("cities").where("capital", isEqualTo: true).get().then( (querySnapshot) { print("Successfully completed"); for (var docSnapshot in querySnapshot.docs) { print('${docSnapshot.id} => ${docSnapshot.data()}'); } }, onError: (e) => print("Error completing: $e"), );
Giava
Pitone
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
andare
PHP
PHP
Per ulteriori informazioni sull'installazione e la creazione di un client Cloud Firestore, fai riferimento a Librerie client Cloud Firestore .
Unità
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#
Rubino
Vedere Ottenere dati per ulteriori informazioni sul recupero dei risultati della query. Puoi anche aggiungere un listener a una query per ottenere i risultati correnti e ascoltare gli aggiornamenti futuri.
Operatori di interrogazione
Il metodo where()
accetta tre parametri: un campo su cui filtrare, un operatore di confronto e un valore. Cloud Firestore supporta i seguenti operatori di confronto:
-
<
meno di -
<=
minore o uguale a -
==
uguale a -
>
maggiore di -
>=
maggiore o uguale a -
!=
non uguale a -
array-contains
-
array-contains-any
-
in
-
not-in
Per esempio:
Web version 9
const stateQuery = query(citiesRef, where("state", "==", "CA")); const populationQuery = query(citiesRef, where("population", "<", 100000)); const nameQuery = query(citiesRef, where("name", ">=", "San Francisco"));
Web version 8
const stateQuery = citiesRef.where("state", "==", "CA"); const populationQuery = citiesRef.where("population", "<", 100000); const nameQuery = citiesRef.where("name", ">=", "San Francisco");
Rapido
let stateQuery = citiesRef.whereField("state", isEqualTo: "CA") let populationQuery = citiesRef.whereField("population", isLessThan: 100000) let nameQuery = citiesRef.whereField("name", isGreaterThanOrEqualTo: "San Francisco")
Obiettivo-C
FIRQuery *stateQuery = [citiesRef queryWhereField:@"state" isEqualTo:@"CA"]; FIRQuery *populationQuery = [citiesRef queryWhereField:@"population" isLessThan:@100000]; FIRQuery *nameQuery = [citiesRef queryWhereField:@"name" isGreaterThanOrEqualTo:@"San Francisco"];
Kotlin+KTX
val stateQuery = citiesRef.whereEqualTo("state", "CA") val populationQuery = citiesRef.whereLessThan("population", 100000) val nameQuery = citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco")
Java
Query stateQuery = citiesRef.whereEqualTo("state", "CA"); Query populationQuery = citiesRef.whereLessThan("population", 100000); Query nameQuery = citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco");
Dart
final citiesRef = db.collection("cities"); final stateQuery = citiesRef.where("state", isEqualTo: "CA"); final populationQuery = citiesRef.where("population", isLessThan: 100000); final nameQuery = citiesRef.where("name", isEqualTo: "San Francisco");
Giava
Pitone
Python
C++
cities_ref.WhereEqualTo("state", FieldValue::String("CA")); cities_ref.WhereLessThan("population", FieldValue::Integer(100000)); cities_ref.WhereGreaterThanOrEqualTo("name", FieldValue::String("San Francisco"));
Node.js
andare
PHP
Unità
Query stateQuery = citiesRef.WhereEqualTo("State", "CA"); Query populationQuery = citiesRef.WhereGreaterThan("Population", 1000000); Query nameQuery = citiesRef.WhereGreaterThanOrEqualTo("Name", "San Francisco");
C#
Rubino
Non uguale ( !=
)
Utilizzare l'operatore non uguale ( !=
) per restituire i documenti in cui il campo specificato esiste e non corrisponde al valore di confronto. Per esempio:
Web version 9
const notCapitalQuery = query(citiesRef, where("capital", "!=", false));
Web version 8
citiesRef.where("capital", "!=", false);
Rapido
let notEqualQuery = citiesRef.whereField("capital", isNotEqualTo: false)
Obiettivo-C
query = [citiesRef queryWhereField:@"capital" isNotEqualTo:@NO];
Kotlin+KTX
val notCapitalQuery = citiesRef.whereNotEqualTo("capital", false)
Java
Query notCapitalQuery = citiesRef.whereNotEqualTo("capital", false);
Dart
final citiesRef = db.collection("cities"); final notCapitals = citiesRef.where("capital", isNotEqualTo: true);
Giava
Pitone
// Snippet not yet available
C++
// Snippet not yet available
Node.js
andare
// Snippet not yet available
PHP
Unità
// Snippet not yet available
C#
// Snippet not yet available
Rubino
Questa query restituisce ogni documento di city
in cui esiste il campo capital
con un valore diverso da false
o null
. Ciò include i documenti di city
in cui il valore del campo capital
è uguale a true
o qualsiasi valore non booleano oltre a null
.
Questa query non restituisce documenti di city
in cui il campo capital
non esiste. Le query non uguali ( !=
) e not-in
escludono i documenti in cui il campo specificato non esiste .
Un campo esiste quando è impostato su qualsiasi valore, inclusa una stringa vuota ( ""
), null
e NaN
(non un numero). Si noti che i valori di campo null
non corrispondono alle clausole !=
, perché x != null
restituisce undefined
.
Limitazioni
Tieni presente le seguenti limitazioni per le query !=
:
- Solo i documenti in cui esiste il campo specificato possono corrispondere alla query.
- Non puoi combinare
not-in
e!=
in una query composta. - In una query composta, i confronti intervallo (
<
,<=
,>
,>=
) e non uguale (!=
,not-in
) devono filtrare tutti sullo stesso campo.
Adesione all'array
È possibile utilizzare l'operatore array-contains
per filtrare in base ai valori dell'array. Per esempio:
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where("regions", "array-contains", "west_coast"));
Web version 8
citiesRef.where("regions", "array-contains", "west_coast");
Rapido
citiesRef .whereField("regions", arrayContains: "west_coast")
Obiettivo-C
[citiesRef queryWhereField:@"state" arrayContains:@"west_coast"];
Kotlin+KTX
val citiesRef = db.collection("cities") citiesRef.whereArrayContains("regions", "west_coast")
Java
CollectionReference citiesRef = db.collection("cities"); citiesRef.whereArrayContains("regions", "west_coast");
Dart
final citiesRef = db.collection("cities"); final westCoastcities = citiesRef.where("regions", arrayContains: "west_coast");
Giava
Pitone
Python
C++
CollectionReference cities_ref = db->Collection("cities"); cities_ref.WhereArrayContains("region", FieldValue::String("west_coast"));
Node.js
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); Query arrayContainsQuery = citiesRef.WhereArrayContains("region", "west_coast");
C#
Rubino
Questa query restituisce ogni documento di city
in cui il campo west_coast
regions
Se l'array ha più istanze del valore su cui si esegue la query, il documento viene incluso nei risultati solo una volta.
È possibile utilizzare al massimo una clausola array-contains
per query. Non puoi combinare array-contains
con array-contains-any
.
in
, not-in
e array-contains-any
Utilizzare l'operatore in
per combinare fino a 10 clausole di uguaglianza ( ==
) sullo stesso campo con un OR
logico. Una query in
restituisce i documenti in cui il campo specificato corrisponde a uno qualsiasi dei valori di confronto. Per esempio:
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where('country', 'in', ['USA', 'Japan']));
Web version 8
citiesRef.where('country', 'in', ['USA', 'Japan']);
Rapido
let citiesRef = db.collection("cities") citiesRef.whereField("country", in: ["USA", "Japan"])
Obiettivo-C
FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"]; [citiesRef queryWhereField:@"country" in:@[@"USA", @"Japan"]];
Kotlin+KTX
val citiesRef = db.collection("cities") citiesRef.whereIn("country", listOf("USA", "Japan"))
Java
CollectionReference citiesRef = db.collection("cities"); citiesRef.whereIn("country", Arrays.asList("USA", "Japan"));
Dart
final citiesRef = db.collection("cities"); final cities = citiesRef.where("country", whereIn: ["USA", "Japan"]);
Giava
Pitone
Python
C++
CollectionReference cities_ref = db->Collection("cities"); cities_ref.WhereIn("country", std::vector<FieldValue> { FieldValue::String("USA"), FieldValue::String("Japan") });
Node.js
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); ListcountriesList = new List<object>() {"USA", "Japan"}; Query whereInQuery = citiesRef.WhereIn("country", countriesList);
C#
Rubino
Questa query restituisce ogni documento di city
in cui il campo country
è impostato su USA
o Japan
. Dai dati di esempio, questo include i documenti SF
, LA
, DC
e TOK
.
not-in
Utilizzare l'operatore not-in
per combinare fino a 10 clausole non uguale ( !=
) sullo stesso campo con un AND
logico. Una query not-in
restituisce i documenti in cui esiste il campo specificato, non è null
e non corrisponde a nessuno dei valori di confronto. Per esempio:
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where('country', 'not-in', ['USA', 'Japan']));
Web version 8
citiesRef.where('country', 'not-in', ['USA', 'Japan']);
Rapido
citiesRef.whereField("country", notIn: ["USA", "Japan"])
Obiettivo-C
[citiesRef queryWhereField:@"country" notIn:@[@"USA", @"Japan"]];
Kotlin+KTX
citiesRef.whereNotIn("country", listOf("USA", "Japan"))
Java
citiesRef.whereNotIn("country", Arrays.asList("USA", "Japan"));
Dart
final citiesRef = db.collection("cities"); final cities = citiesRef.where("country", whereNotIn: ["USA", "Japan"]);
Giava
Pitone
// Snippet not yet available
C++
cities_ref.WhereNotIn("country", std::vector<FieldValue> { FieldValue::String("USA"), FieldValue::String("Japan") });
Node.js
andare
// Snippet not yet available
PHP
Unità
// Snippet not yet available
C#
// Snippet not yet available
Rubino
Questa query restituisce ogni documento di city
in cui esiste il campo country
e non è impostato su USA
, Japan
o null
. Dai dati di esempio, questo include i documenti di London
e Hong Kong
.
le query not-in
escludono i documenti in cui il campo specificato non esiste. Un campo esiste quando è impostato su qualsiasi valore, inclusa una stringa vuota ( ""
), null
e NaN
(non un numero). Si noti che x != null
restituisce undefined
. Una query not-in
con null
come uno dei valori di confronto non corrisponde ad alcun documento.
array-contains-any
Utilizzare l'operatore array-contains-any
per combinare fino a 10 clausole array-contains
sullo stesso campo con un OR
logico. Una query array-contains-any
restituisce documenti in cui il campo specificato è un array che contiene uno o più dei valori di confronto:
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where('regions', 'array-contains-any', ['west_coast', 'east_coast']));
Web version 8
citiesRef.where('regions', 'array-contains-any', ['west_coast', 'east_coast']);
Rapido
let citiesRef = db.collection("cities") citiesRef.whereField("regions", arrayContainsAny: ["west_coast", "east_coast"])
Obiettivo-C
FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"]; [citiesRef queryWhereField:@"regions" arrayContainsAny:@[@"west_coast", @"east_coast"]];
Kotlin+KTX
val citiesRef = db.collection("cities") citiesRef.whereArrayContainsAny("regions", listOf("west_coast", "east_coast"))
Java
CollectionReference citiesRef = db.collection("cities"); citiesRef.whereArrayContainsAny("regions", Arrays.asList("west_coast", "east_coast"));
Dart
final citiesRef = db.collection("cities"); final cities = citiesRef .where("regions", arrayContainsAny: ["west_coast", "east_coast"]);
Giava
Pitone
Python
C++
CollectionReference cities_ref = db->Collection("cities"); cities_ref.WhereArrayContainsAny("region", std::vector<FieldValue> { FieldValue::String("west_coast"), FieldValue::String("east_coast") });
Node.js
andare
PHP
Unità
CollectionReference citiesRef = db.Collection("cities"); ListregionsList = new List<object>() {"west_coast", "east_coast"}; Query arrayContainsAnyQuery = citiesRef.WhereArrayContainsAny("regions", regionsList);
C#
Rubino
Questa query restituisce ogni documento di città in cui il campo west_coast
regions
east_coast
. Dai dati di esempio, questo include i documenti SF
, LA
e DC
.
I risultati di array-contains-any
vengono deduplicati. Anche se il campo matrice di un documento corrisponde a più di uno dei valori di confronto, il set di risultati include tale documento solo una volta.
array-contains-any
filtra sempre in base al tipo di dati dell'array. Ad esempio, la query precedente non restituirebbe un documento di città dove invece di un array, il campo west_coast
regions
È possibile utilizzare un valore di matrice come valore di confronto per in
, ma a differenza array-contains-any
, la clausola corrisponde a una corrispondenza esatta di lunghezza, ordine e valori dell'array. Per esempio:
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where('regions', 'in', [['west_coast', 'east_coast']]));
Web version 8
citiesRef.where('regions', 'in', [['west_coast', 'east_coast']]);
Rapido
citiesRef.whereField("regions", in: [["west_coast"], ["east_coast"]]);
Obiettivo-C
[citiesRef queryWhereField:@"regions" in:@[@[@"west_coast"], @[@"east_coast"]]];
Kotlin+KTX
citiesRef.whereIn("regions", listOf(arrayOf("west_coast"), arrayOf("east_coast")))
Java
citiesRef.whereIn("regions", Arrays.asList(new String[]{"west_coast"}, new String[]{"east_coast"}));
Dart
final citiesRef = db.collection("cities"); final cities = citiesRef.where("regions", whereIn: [ ["west_coast"], ["east_coast"] ]);
Giava
Pitone
Python
C++
cities_ref.WhereIn("region", std::vector<FieldValue> { FieldValue::String("west_coast"), FieldValue::String("east_coast") });
Node.js
andare
PHP
Unità
// Not yet supported in the Unity SDK
C#
Rubino
Questa query restituisce ogni documento di città in cui il campo west_coast
regions
east_coast
. Dai dati di esempio, solo il documento DC
si qualifica con il relativo campo region di [" regions
["east_coast"]
. Il documento SF
, tuttavia, non corrisponde perché il suo campo region è [" regions
["west_coast", "norcal"]
.
Limitazioni
Nota le seguenti limitazioni per in
, not-in
e array-contains-any
:
-
in
,not-in
earray-contains-any
supportano fino a 10 valori di confronto. - È possibile utilizzare al massimo una clausola
array-contains
per query. Non puoi combinarearray-contains
conarray-contains-any
. - È possibile utilizzare al massimo una clausola
in
,not-in
oarray-contains-any
per query. Non puoi combinare questi operatori nella stessa query. - Non puoi combinare
not-in
con non uguale!=
. - Non è possibile ordinare la query in base a un campo incluso in un'uguaglianza (
==
) oin
una clausola.
Query composte
È possibile concatenare più metodi di operatori di uguaglianza ( ==
o array-contains
) per creare query più specifiche ( AND
logico). Tuttavia, è necessario creare un indice composito per combinare gli operatori di uguaglianza con gli operatori di disuguaglianza <
, <=
, >
e !=
.
Web version 9
import { query, where } from "firebase/firestore"; const q1 = query(citiesRef, where("state", "==", "CO"), where("name", "==", "Denver")); const q2 = query(citiesRef, where("state", "==", "CA"), where("population", "<", 1000000));
Web version 8
const q1 = citiesRef.where("state", "==", "CO").where("name", "==", "Denver"); const q2 = citiesRef.where("state", "==", "CA").where("population", "<", 1000000);
Rapido
citiesRef .whereField("state", isEqualTo: "CO") .whereField("name", isEqualTo: "Denver") citiesRef .whereField("state", isEqualTo: "CA") .whereField("population", isLessThan: 1000000)
Obiettivo-C
[[citiesRef queryWhereField:@"state" isEqualTo:@"CO"] queryWhereField:@"name" isGreaterThanOrEqualTo:@"Denver"]; [[citiesRef queryWhereField:@"state" isEqualTo:@"CA"] queryWhereField:@"population" isLessThan:@1000000];
Kotlin+KTX
citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver") citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000)
Java
citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver"); citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000);
Dart
final citiesRef = db.collection("cities"); citiesRef .where("state", isEqualTo: "CO") .where("name", isEqualTo: "Denver"); citiesRef .where("state", isEqualTo: "CA") .where("population", isLessThan: 1000000);
Giava
Pitone
Python
C++
cities_ref.WhereEqualTo("state", FieldValue::String("CO")) .WhereEqualTo("name", FieldValue::String("Denver")); cities_ref.WhereEqualTo("state", FieldValue::String("CA")) .WhereLessThan("population", FieldValue::Integer(1000000));
Node.js
andare
PHP
Unità
Query chainedQuery = citiesRef .WhereEqualTo("State", "CA") .WhereEqualTo("Name", "San Francisco");
C#
Rubino
È possibile eseguire confronti di intervallo ( <
, <=
, >
, >=
) o non uguale a ( !=
) solo su un singolo campo ed è possibile includere al massimo una clausola array-contains
o array-contains-any
in una query composta :
Valido : l'intervallo filtra su un solo campo
Web version 9
import { query, where } from "firebase/firestore"; const q1 = query(citiesRef, where("state", ">=", "CA"), where("state", "<=", "IN")); const q2 = query(citiesRef, where("state", "==", "CA"), where("population", ">", 1000000));
Web version 8
const q1 = citiesRef.where("state", ">=", "CA").where("state", "<=", "IN"); const q2 = citiesRef.where("state", "==", "CA").where("population", ">", 1000000);
Rapido
citiesRef .whereField("state", isGreaterThanOrEqualTo: "CA") .whereField("state", isLessThanOrEqualTo: "IN") citiesRef .whereField("state", isEqualTo: "CA") .whereField("population", isGreaterThan: 1000000)
Obiettivo-C
[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"] queryWhereField:@"state" isLessThanOrEqualTo:@"IN"]; [[citiesRef queryWhereField:@"state" isEqualTo:@"CA"] queryWhereField:@"population" isGreaterThan:@1000000];
Kotlin+KTX
citiesRef.whereGreaterThanOrEqualTo("state", "CA") .whereLessThanOrEqualTo("state", "IN") citiesRef.whereEqualTo("state", "CA") .whereGreaterThan("population", 1000000)
Java
citiesRef.whereGreaterThanOrEqualTo("state", "CA") .whereLessThanOrEqualTo("state", "IN"); citiesRef.whereEqualTo("state", "CA") .whereGreaterThan("population", 1000000);
Dart
final citiesRef = db.collection("cities"); citiesRef .where("state", isGreaterThanOrEqualTo: "CA") .where("state", isLessThanOrEqualTo: "IN"); citiesRef .where("state", isEqualTo: "CA") .where("population", isGreaterThan: 1000000);
Giava
Pitone
Python
C++
cities_ref.WhereGreaterThanOrEqualTo("state", FieldValue::String("CA")) .WhereLessThanOrEqualTo("state", FieldValue::String("IN")); cities_ref.WhereEqualTo("state", FieldValue::String("CA")) .WhereGreaterThan("population", FieldValue::Integer(1000000));
Node.js
andare
PHP
Unità
Query rangeQuery = citiesRef .WhereGreaterThanOrEqualTo("State", "CA") .WhereLessThanOrEqualTo("State", "IN");
C#
Rubino
Non valido : filtri di intervallo su campi diversi
Web version 9
import { query, where } from "firebase/firestore"; const q = query(citiesRef, where("state", ">=", "CA"), where("population", ">", 100000));
Web version 8
citiesRef.where("state", ">=", "CA").where("population", ">", 100000);
Rapido
citiesRef .whereField("state", isGreaterThanOrEqualTo: "CA") .whereField("population", isGreaterThan: 1000000)
Obiettivo-C
[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"] queryWhereField:@"population" isGreaterThan:@1000000];
Kotlin+KTX
citiesRef.whereGreaterThanOrEqualTo("state", "CA") .whereGreaterThan("population", 100000)
Java
citiesRef.whereGreaterThanOrEqualTo("state", "CA").whereGreaterThan("population", 100000);
Dart
final citiesRef = db.collection("cities"); citiesRef .where("state", isGreaterThanOrEqualTo: "CA") .where("population", isGreaterThan: 1000000);
Giava
Pitone
Python
C++
// BAD EXAMPLE -- will crash the program: cities_ref.WhereGreaterThanOrEqualTo("state", FieldValue::String("CA")) .WhereGreaterThan("population", FieldValue::Integer(100000));
Node.js
andare
PHP
Unità
Query invalidRangeQuery = citiesRef .WhereGreaterThanOrEqualTo("State", "CA") .WhereGreaterThan("Population", 1000000);
C#
Rubino
Query sui gruppi di raccolta
Un gruppo di raccolte è costituito da tutte le raccolte con lo stesso ID. Per impostazione predefinita, le query recuperano i risultati da una singola raccolta nel database. Utilizzare una query del gruppo di raccolta per recuperare i documenti da un gruppo di raccolta invece che da una singola raccolta.
Ad esempio, puoi creare un gruppo di raccolte di landmarks
di riferimento aggiungendo una sottoraccolta di punti di riferimento a ciascuna città:
Web version 9
import { collection, addDoc } from "firebase/firestore"; const citiesRef = collection(db, 'cities'); await Promise.all([ addDoc(collection(citiesRef, 'SF', 'landmarks'), { name: 'Golden Gate Bridge', type: 'bridge' }), addDoc(collection(citiesRef, 'SF', 'landmarks'), { name: 'Legion of Honor', type: 'museum' }), addDoc(collection(citiesRef, 'LA', 'landmarks'), { name: 'Griffith Park', type: 'park' }), addDoc(collection(citiesRef, 'LA', 'landmarks'), { name: 'The Getty', type: 'museum' }), addDoc(collection(citiesRef, 'DC', 'landmarks'), { name: 'Lincoln Memorial', type: 'memorial' }), addDoc(collection(citiesRef, 'DC', 'landmarks'), { name: 'National Air and Space Museum', type: 'museum' }), addDoc(collection(citiesRef, 'TOK', 'landmarks'), { name: 'Ueno Park', type: 'park' }), addDoc(collection(citiesRef, 'TOK', 'landmarks'), { name: 'National Museum of Nature and Science', type: 'museum' }), addDoc(collection(citiesRef, 'BJ', 'landmarks'), { name: 'Jingshan Park', type: 'park' }), addDoc(collection(citiesRef, 'BJ', 'landmarks'), { name: 'Beijing Ancient Observatory', type: 'museum' }) ]);
Web version 8
var citiesRef = db.collection('cities'); var landmarks = Promise.all([ citiesRef.doc('SF').collection('landmarks').doc().set({ name: 'Golden Gate Bridge', type: 'bridge' }), citiesRef.doc('SF').collection('landmarks').doc().set({ name: 'Legion of Honor', type: 'museum' }), citiesRef.doc('LA').collection('landmarks').doc().set({ name: 'Griffith Park', type: 'park' }), citiesRef.doc('LA').collection('landmarks').doc().set({ name: 'The Getty', type: 'museum' }), citiesRef.doc('DC').collection('landmarks').doc().set({ name: 'Lincoln Memorial', type: 'memorial' }), citiesRef.doc('DC').collection('landmarks').doc().set({ name: 'National Air and Space Museum', type: 'museum' }), citiesRef.doc('TOK').collection('landmarks').doc().set({ name: 'Ueno Park', type: 'park' }), citiesRef.doc('TOK').collection('landmarks').doc().set({ name: 'National Museum of Nature and Science', type: 'museum' }), citiesRef.doc('BJ').collection('landmarks').doc().set({ name: 'Jingshan Park', type: 'park' }), citiesRef.doc('BJ').collection('landmarks').doc().set({ name: 'Beijing Ancient Observatory', type: 'museum' }) ]);
Rapido
let citiesRef = db.collection("cities") var data = ["name": "Golden Gate Bridge", "type": "bridge"] citiesRef.document("SF").collection("landmarks").addDocument(data: data) data = ["name": "Legion of Honor", "type": "museum"] citiesRef.document("SF").collection("landmarks").addDocument(data: data) data = ["name": "Griffith Park", "type": "park"] citiesRef.document("LA").collection("landmarks").addDocument(data: data) data = ["name": "The Getty", "type": "museum"] citiesRef.document("LA").collection("landmarks").addDocument(data: data) data = ["name": "Lincoln Memorial", "type": "memorial"] citiesRef.document("DC").collection("landmarks").addDocument(data: data) data = ["name": "National Air and Space Museum", "type": "museum"] citiesRef.document("DC").collection("landmarks").addDocument(data: data) data = ["name": "Ueno Park", "type": "park"] citiesRef.document("TOK").collection("landmarks").addDocument(data: data) data = ["name": "National Museum of Nature and Science", "type": "museum"] citiesRef.document("TOK").collection("landmarks").addDocument(data: data) data = ["name": "Jingshan Park", "type": "park"] citiesRef.document("BJ").collection("landmarks").addDocument(data: data) data = ["name": "Beijing Ancient Observatory", "type": "museum"] citiesRef.document("BJ").collection("landmarks").addDocument(data: data)
Obiettivo-C
FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"]; NSDictionary *data = @{@"name": @"Golden Gate Bridge", @"type": @"bridge"}; [[[citiesRef documentWithPath:@"SF"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Legion of Honor", @"type": @"museum"}; [[[citiesRef documentWithPath:@"SF"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Griffith Park", @"type": @"park"}; [[[citiesRef documentWithPath:@"LA"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"The Getty", @"type": @"museum"}; [[[citiesRef documentWithPath:@"LA"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Lincoln Memorial", @"type": @"memorial"}; [[[citiesRef documentWithPath:@"DC"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"National Air and Space Museum", @"type": @"museum"}; [[[citiesRef documentWithPath:@"DC"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Ueno Park", @"type": @"park"}; [[[citiesRef documentWithPath:@"TOK"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"National Museum of Nature and Science", @"type": @"museum"}; [[[citiesRef documentWithPath:@"TOK"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Jingshan Park", @"type": @"park"}; [[[citiesRef documentWithPath:@"BJ"] collectionWithPath:@"landmarks"] addDocumentWithData:data]; data = @{@"name": @"Beijing Ancient Observatory", @"type": @"museum"}; [[[citiesRef documentWithPath:@"BJ"] collectionWithPath:@"landmarks"] addDocumentWithData:data];
Kotlin+KTX
val citiesRef = db.collection("cities") val ggbData = mapOf( "name" to "Golden Gate Bridge", "type" to "bridge" ) citiesRef.document("SF").collection("landmarks").add(ggbData) val lohData = mapOf( "name" to "Legion of Honor", "type" to "museum" ) citiesRef.document("SF").collection("landmarks").add(lohData) val gpData = mapOf( "name" to "Griffth Park", "type" to "park" ) citiesRef.document("LA").collection("landmarks").add(gpData) val tgData = mapOf( "name" to "The Getty", "type" to "museum" ) citiesRef.document("LA").collection("landmarks").add(tgData) val lmData = mapOf( "name" to "Lincoln Memorial", "type" to "memorial" ) citiesRef.document("DC").collection("landmarks").add(lmData) val nasaData = mapOf( "name" to "National Air and Space Museum", "type" to "museum" ) citiesRef.document("DC").collection("landmarks").add(nasaData) val upData = mapOf( "name" to "Ueno Park", "type" to "park" ) citiesRef.document("TOK").collection("landmarks").add(upData) val nmData = mapOf( "name" to "National Musuem of Nature and Science", "type" to "museum" ) citiesRef.document("TOK").collection("landmarks").add(nmData) val jpData = mapOf( "name" to "Jingshan Park", "type" to "park" ) citiesRef.document("BJ").collection("landmarks").add(jpData) val baoData = mapOf( "name" to "Beijing Ancient Observatory", "type" to "musuem" ) citiesRef.document("BJ").collection("landmarks").add(baoData)
Java
CollectionReference citiesRef = db.collection("cities"); Map<String, Object> ggbData = new HashMap<>(); ggbData.put("name", "Golden Gate Bridge"); ggbData.put("type", "bridge"); citiesRef.document("SF").collection("landmarks").add(ggbData); Map<String, Object> lohData = new HashMap<>(); lohData.put("name", "Legion of Honor"); lohData.put("type", "museum"); citiesRef.document("SF").collection("landmarks").add(lohData); Map<String, Object> gpData = new HashMap<>(); gpData.put("name", "Griffith Park"); gpData.put("type", "park"); citiesRef.document("LA").collection("landmarks").add(gpData); Map<String, Object> tgData = new HashMap<>(); tgData.put("name", "The Getty"); tgData.put("type", "museum"); citiesRef.document("LA").collection("landmarks").add(tgData); Map<String, Object> lmData = new HashMap<>(); lmData.put("name", "Lincoln Memorial"); lmData.put("type", "memorial"); citiesRef.document("DC").collection("landmarks").add(lmData); Map<String, Object> nasaData = new HashMap<>(); nasaData.put("name", "National Air and Space Museum"); nasaData.put("type", "museum"); citiesRef.document("DC").collection("landmarks").add(nasaData); Map<String, Object> upData = new HashMap<>(); upData.put("name", "Ueno Park"); upData.put("type", "park"); citiesRef.document("TOK").collection("landmarks").add(upData); Map<String, Object> nmData = new HashMap<>(); nmData.put("name", "National Museum of Nature and Science"); nmData.put("type", "museum"); citiesRef.document("TOK").collection("landmarks").add(nmData); Map<String, Object> jpData = new HashMap<>(); jpData.put("name", "Jingshan Park"); jpData.put("type", "park"); citiesRef.document("BJ").collection("landmarks").add(jpData); Map<String, Object> baoData = new HashMap<>(); baoData.put("name", "Beijing Ancient Observatory"); baoData.put("type", "museum"); citiesRef.document("BJ").collection("landmarks").add(baoData);
Dart
final citiesRef = db.collection("cities"); final ggbData = {"name": "Golden Gate Bridge", "type": "bridge"}; citiesRef.doc("SF").collection("landmarks").add(ggbData); final lohData = {"name": "Legion of Honor", "type": "museum"}; citiesRef.doc("SF").collection("landmarks").add(lohData); final gpData = {"name": "Griffth Park", "type": "park"}; citiesRef.doc("LA").collection("landmarks").add(gpData); final tgData = {"name": "The Getty", "type": "museum"}; citiesRef.doc("LA").collection("landmarks").add(tgData); final lmData = {"name": "Lincoln Memorial", "type": "memorial"}; citiesRef.doc("DC").collection("landmarks").add(lmData); final nasaData = { "name": "National Air and Space Museum", "type": "museum" }; citiesRef.doc("DC").collection("landmarks").add(nasaData); final upData = {"name": "Ueno Park", "type": "park"}; citiesRef.doc("TOK").collection("landmarks").add(upData); final nmData = { "name": "National Musuem of Nature and Science", "type": "museum" }; citiesRef.doc("TOK").collection("landmarks").add(nmData); final jpData = {"name": "Jingshan Park", "type": "park"}; citiesRef.doc("BJ").collection("landmarks").add(jpData); final baoData = {"name": "Beijing Ancient Observatory", "type": "musuem"}; citiesRef.doc("BJ").collection("landmarks").add(baoData);
Giava
Pitone
Python
C++
// This is not yet supported.
Node.js
andare
PHP
Unità
// Not yet supported in the Unity SDK
C#
Rubino
Possiamo usare la query semplice e composta descritta in precedenza per interrogare la sottoraccolta di punti di landmarks
di una singola città, ma potresti anche voler recuperare i risultati dalla sottoraccolta di punti di landmarks
di ogni città contemporaneamente.
Il gruppo di raccolta dei landmarks
è costituito da tutte le raccolte con l'ID punti di landmarks
ed è possibile interrogarlo utilizzando una query del gruppo di raccolta. Ad esempio, questa query del gruppo di raccolta recupera tutti i punti di riferimento del museum
in tutte le città:
Web version 9
import { collectionGroup, query, where, getDocs } from "firebase/firestore"; const museums = query(collectionGroup(db, 'landmarks'), where('type', '==', 'museum')); const querySnapshot = await getDocs(museums); querySnapshot.forEach((doc) => { console.log(doc.id, ' => ', doc.data()); });
Web version 8
var museums = db.collectionGroup('landmarks').where('type', '==', 'museum'); museums.get().then((querySnapshot) => { querySnapshot.forEach((doc) => { console.log(doc.id, ' => ', doc.data()); }); });
Rapido
db.collectionGroup("landmarks").whereField("type", isEqualTo: "museum").getDocuments { (snapshot, error) in // ... }
Obiettivo-C
[[[self.db collectionGroupWithID:@"landmarks"] queryWhereField:@"type" isEqualTo:@"museum"] getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) { // ... }];
Kotlin+KTX
db.collectionGroup("landmarks").whereEqualTo("type", "museum").get() .addOnSuccessListener { queryDocumentSnapshots -> // ... }
Java
db.collectionGroup("landmarks").whereEqualTo("type", "museum").get() .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() { @Override public void onSuccess(QuerySnapshot queryDocumentSnapshots) { // ... } });
Dart
db .collectionGroup("landmarks") .where("type", isEqualTo: "museum") .get() .then( (res) => print("Successfully completed"), onError: (e) => print("Error completing: $e"), );
Giava
Pitone
Python
C++
// This is not yet supported.
Node.js
andare
PHP
Unità
// Not yet supported in the Unity SDK
C#
Rubino
Prima di utilizzare una query del gruppo di raccolta, è necessario creare un indice che supporti la query del gruppo di raccolta. Puoi creare un indice tramite un messaggio di errore, la console o l'interfaccia a riga di comando di Firebase .
Per gli SDK Web e per dispositivi mobili, devi anche creare regole che consentano le query del gruppo di raccolta .
Limitazioni delle query
Il seguente elenco riepiloga i limiti delle query di Cloud Firestore:
- Cloud Firestore fornisce un supporto limitato per le query
OR
logiche. Gli operatoriin
earray-contains-any
supportano unOR
logico fino a 10 condizioni di uguaglianza (==
) oarray-contains
su un singolo campo. Per gli altri casi, crea una query separata per ogni condizioneOR
e unisci i risultati della query nella tua app. - In una query composta, i confronti intervallo (
<
,<=
,>
,>=
) e non uguale (!=
,not-in
) devono filtrare tutti sullo stesso campo. - È possibile utilizzare al massimo una clausola
array-contains
per query. Non puoi combinarearray-contains
conarray-contains-any
. - È possibile utilizzare al massimo una clausola
in
,not-in
oarray-contains-any
per query. Non puoi combinarein
,not-in
earray-contains-any
nella stessa query. - Non è possibile ordinare la query in base a un campo incluso in un'uguaglianza (
==
) oin
una clausola. - La somma di filtri, ordinamenti e percorso del documento padre (1 per una sottoraccolta, 0 per una raccolta radice) in una query non può superare 100.
E dopo?
- Scopri come ordinare e limitare i dati nei risultati delle query .
- Salva le letture quando vuoi semplicemente contare i risultati .