查询和过滤数据

Firestore 提供了强大的查询功能，用于指定您要从集合或集合组中检索哪些文档。这些查询也可以与 get() 或 addSnapshotListener() 配合使用，如获取数据和获取实时更新中所述。

示例数据

首先，写入一些关于城市的数据，以便我们具体了解读取数据的不同方式：

Web

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

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

Swift

let citiesRef = db.collection("cities")

citiesRef.document("SF").setData([
    "name": "San Francisco",
    "state": "CA",
    "country": "USA",
    "capital": false,
    "population": 860000,
    "regions": ["west_coast", "norcal"]
    ])
citiesRef.document("LA").setData([
    "name": "Los Angeles",
    "state": "CA",
    "country": "USA",
    "capital": false,
    "population": 3900000,
    "regions": ["west_coast", "socal"]
    ])
citiesRef.document("DC").setData([
    "name": "Washington D.C.",
    "country": "USA",
    "capital": true,
    "population": 680000,
    "regions": ["east_coast"]
    ])
citiesRef.document("TOK").setData([
    "name": "Tokyo",
    "country": "Japan",
    "capital": true,
    "population": 9000000,
    "regions": ["kanto", "honshu"]
    ])
citiesRef.document("BJ").setData([
    "name": "Beijing",
    "country": "China",
    "capital": true,
    "population": 21500000,
    "regions": ["jingjinji", "hebei"]
    ])ViewController.swift

Objective-C

FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"];
[[citiesRef documentWithPath:@"SF"] setData:@{
  @"name": @"San Francisco",
  @"state": @"CA",
  @"country": @"USA",
  @"capital": @(NO),
  @"population": @860000,
  @"regions": @[@"west_coast", @"norcal"]
}];
[[citiesRef documentWithPath:@"LA"] setData:@{
  @"name": @"Los Angeles",
  @"state": @"CA",
  @"country": @"USA",
  @"capital": @(NO),
  @"population": @3900000,
  @"regions": @[@"west_coast", @"socal"]
}];
[[citiesRef documentWithPath:@"DC"] setData:@{
  @"name": @"Washington D.C.",
  @"country": @"USA",
  @"capital": @(YES),
  @"population": @680000,
  @"regions": @[@"east_coast"]
}];
[[citiesRef documentWithPath:@"TOK"] setData:@{
  @"name": @"Tokyo",
  @"country": @"Japan",
  @"capital": @(YES),
  @"population": @9000000,
  @"regions": @[@"kanto", @"honshu"]
}];
[[citiesRef documentWithPath:@"BJ"] setData:@{
  @"name": @"Beijing",
  @"country": @"China",
  @"capital": @(YES),
  @"population": @21500000,
  @"regions": @[@"jingjinji", @"hebei"]
}];ViewController.m

Java
Android

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

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

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

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

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

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

Kotlin+KTX
Android

val cities = db.collection("cities")

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

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

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

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

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

Java

CollectionReference cities = db.collection("cities");
List<ApiFuture<WriteResult>> futures = new ArrayList<>();
futures.add(
    cities
        .document("SF")
        .set(
            new City(
                "San Francisco",
                "CA",
                "USA",
                false,
                860000L,
                Arrays.asList("west_coast", "norcal"))));
futures.add(
    cities
        .document("LA")
        .set(
            new City(
                "Los Angeles",
                "CA",
                "USA",
                false,
                3900000L,
                Arrays.asList("west_coast", "socal"))));
futures.add(
    cities
        .document("DC")
        .set(
            new City(
                "Washington D.C.", null, "USA", true, 680000L, Arrays.asList("east_coast"))));
futures.add(
    cities
        .document("TOK")
        .set(
            new City(
                "Tokyo", null, "Japan", true, 9000000L, Arrays.asList("kanto", "honshu"))));
futures.add(
    cities
        .document("BJ")
        .set(
            new City(
                "Beijing",
                null,
                "China",
                true,
                21500000L,
                Arrays.asList("jingjinji", "hebei"))));
// (optional) block on documents successfully added
ApiFutures.allAsList(futures).get();QueryDataSnippets.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())snippets.py

C++

CollectionReference cities = db->Collection("cities");

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

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

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

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

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

Node.js

const citiesRef = db.collection('cities');

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

Go

cities := []struct {
	id string
	c  City
}{
	{
		id: "SF",
		c: City{Name: "San Francisco", State: "CA", Country: "USA",
			Capital: false, Population: 860000,
			Regions: []string{"west_coast", "norcal"}},
	},
	{
		id: "LA",
		c: City{Name: "Los Angeles", State: "CA", Country: "USA",
			Capital: false, Population: 3900000,
			Regions: []string{"west_coast", "socal"}},
	},
	{
		id: "DC",
		c: City{Name: "Washington D.C.", Country: "USA",
			Capital: false, Population: 680000,
			Regions: []string{"east_coast"}},
	},
	{
		id: "TOK",
		c: City{Name: "Tokyo", Country: "Japan",
			Capital: true, Population: 9000000,
			Regions: []string{"kanto", "honshu"}},
	},
	{
		id: "BJ",
		c: City{Name: "Beijing", Country: "China",
			Capital: true, Population: 21500000,
			Regions: []string{"jingjinji", "hebei"}},
	},
}
for _, c := range cities {
	if _, err := client.Collection("cities").Doc(c.id).Set(ctx, c.c); err != nil {
		return err
	}
}query.go

PHP

$citiesRef = $db->collection('cities');
$citiesRef->document('SF')->set([
    'name' => 'San Francisco',
    'state' => 'CA',
    'country' => 'USA',
    'capital' => false,
    'population' => 860000,
    'regions' => ['west_coast', 'norcal']
]);
$citiesRef->document('LA')->set([
    'name' => 'Los Angeles',
    'state' => 'CA',
    'country' => 'USA',
    'capital' => false,
    'population' => 3900000,
    'regions' => ['west_coast', 'socal']
]);
$citiesRef->document('DC')->set([
    'name' => 'Washington D.C.',
    'state' => null,
    'country' => 'USA',
    'capital' => true,
    'population' => 680000,
    'regions' => ['east_coast']
]);
$citiesRef->document('TOK')->set([
    'name' => 'Tokyo',
    'state' => null,
    'country' => 'Japan',
    'capital' => true,
    'population' => 9000000,
    'regions' => ['kanto', 'honshu']
]);
$citiesRef->document('BJ')->set([
    'name' => 'Beijing',
    'state' => null,
    'country' => 'China',
    'capital' => true,
    'population' => 21500000,
    'regions' => ['jingjinji', 'hebei']
]);
printf('Added example cities data to the cities collection.' . PHP_EOL);query_create_examples.php

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 },
    { "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#

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 },
    { "Regions", new ArrayList{"west_coast", "norcal"} }
});
await 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"} }
});
await 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"} }
});
await citiesRef.Document("TOK").SetAsync(new Dictionary<string, object>(){
    { "Name", "Tokyo" },
    { "State", null },
    { "Country", "Japan" },
    { "Capital", true },
    { "Population", 9000000 },
    { "Regions", new ArrayList{"kanto", "honshu"} }
});
await citiesRef.Document("BJ").SetAsync(new Dictionary<string, object>(){
    { "Name", "Beijing" },
    { "State", null },
    { "Country", "China" },
    { "Capital", true },
    { "Population", 21500000 },
    { "Regions", new ArrayList{"jingjinji", "hebei"} }
});
Console.WriteLine("Added example cities data to the cities collection.");Program.cs

Ruby

cities_ref = firestore.col collection_path
cities_ref.doc("SF").set(
  name:       "San Francisco",
  state:      "CA",
  country:    "USA",
  capital:    false,
  population: 860_000,
  regions:    ["west_coast", "norcal"]
)
cities_ref.doc("LA").set(
  name:       "Los Angeles",
  state:      "CA",
  country:    "USA",
  capital:    false,
  population: 3_900_000,
  regions:    ["west_coast", "socal"]
)
cities_ref.doc("DC").set(
  name:       "Washington D.C.",
  state:      nil,
  country:    "USA",
  capital:    true,
  population: 680_000,
  regions:    ["east_coast"]
)
cities_ref.doc("TOK").set(
  name:       "Tokyo",
  state:      nil,
  country:    "Japan",
  capital:    true,
  population: 9_000_000,
  regions:    ["kanto", "honshu"]
)
cities_ref.doc("BJ").set(
  name:       "Beijing",
  state:      nil,
  country:    "China",
  capital:    true,
  population: 21_500_000,
  regions:    ["jingjinji", "hebei"]
)query_data.rb

简单查询

以下查询会返回 CA 州的所有城市：

Web

// Create a reference to the cities collection
var citiesRef = db.collection("cities");

// Create a query against the collection.
var query = citiesRef.where("state", "==", "CA");test.firestore.js

Swift

// 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")ViewController.swift

Objective-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"];ViewController.m

Java
Android

// Create a reference to the cities collection
CollectionReference citiesRef = db.collection("cities");

// Create a query against the collection.
Query query = citiesRef.whereEqualTo("state", "CA");DocSnippets.java

Kotlin+KTX
Android

// Create a reference to the cities collection
val citiesRef = db.collection("cities")

// Create a query against the collection.
val query = citiesRef.whereEqualTo("state", "CA")DocSnippets.kt

Java

// Create a reference to the cities collection
CollectionReference cities = db.collection("cities");
// Create a query against the collection.
Query query = cities.whereEqualTo("state", "CA");
// retrieve  query results asynchronously using query.get()
ApiFuture<QuerySnapshot> querySnapshot = query.get();

for (DocumentSnapshot document : querySnapshot.get().getDocuments()) {
  System.out.println(document.getId());
}QueryDataSnippets.java

Python

# Create a reference to the cities collection
cities_ref = db.collection(u'cities')

# Create a query against the collection
query_ref = cities_ref.where(u'state', u'==', u'CA')snippets.py

C++

CollectionReference cities_ref = db->Collection("cities");
// Create a query against the collection.
Query query_ca =
    cities_ref.WhereEqualTo("state", FieldValue::String("CA"));snippets.cpp

Node.js

// Create a reference to the cities collection
const citiesRef = db.collection('cities');

// Create a query against the collection
const queryRef = citiesRef.where('state', '==', 'CA');index.js

Go

query := client.Collection("cities").Where("state", "==", "CA")query.go

PHP

$citiesRef = $db->collection('cities');
$query = $citiesRef->where('state', '=', 'CA');
$snapshot = $query->documents();
foreach ($snapshot as $document) {
    printf('Document %s returned by query state=CA' . PHP_EOL, $document->id());
}create_query_state.php

Unity

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#

CollectionReference citiesRef = db.Collection("cities");
Query query = citiesRef.WhereEqualTo("State", "CA");
QuerySnapshot querySnapshot = await query.GetSnapshotAsync();
foreach (DocumentSnapshot documentSnapshot in querySnapshot.Documents)
{
    Console.WriteLine("Document {0} returned by query State=CA", documentSnapshot.Id);
}Program.cs

Ruby

cities_ref = firestore.col collection_path

query = cities_ref.where "state", "=", "CA"

query.get do |city|
  puts "Document #{city.document_id} returned by query state=CA."
endquery_data.rb

以下查询会返回首都和所有首府城市：

Web

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

var query = citiesRef.where("capital", "==", true);test.firestore.js

Swift

let capitalCities = db.collection("cities").whereField("capital", isEqualTo: true)ViewController.swift

Objective-C

FIRQuery *capitalCities =
    [[self.db collectionWithPath:@"cities"] queryWhereField:@"capital" isEqualTo:@YES];ViewController.m

Java
Android

Query capitalCities = db.collection("cities").whereEqualTo("capital", true);DocSnippets.java

Kotlin+KTX
Android

val capitalCities = db.collection("cities").whereEqualTo("capital", true)DocSnippets.kt

Java

// Create a reference to the cities collection
CollectionReference cities = db.collection("cities");
// Create a query against the collection.
Query query = cities.whereEqualTo("capital", true);
// retrieve  query results asynchronously using query.get()
ApiFuture<QuerySnapshot> querySnapshot = query.get();

for (DocumentSnapshot document : querySnapshot.get().getDocuments()) {
  System.out.println(document.getId());
}QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

query = cities_ref.where(u'capital', u'==', True)snippets.py

C++

  Query capital_cities = db->Collection("cities").WhereEqualTo(
    "capital", FieldValue::Boolean(true));snippets.cpp

Node.js

// Create a reference to the cities collection
const citiesRef = db.collection('cities');

// Create a query against the collection
const allCapitalsRes = await citiesRef.where('capital', '==', true).get();index.js

Go

query := client.Collection("cities").Where("capital", "==", true)query.go

PHP

$citiesRef = $db->collection('cities');
$query = $citiesRef->where('capital', '=', true);
$snapshot = $query->documents();
foreach ($snapshot as $document) {
    printf('Document %s returned by query capital=true' . PHP_EOL, $document->id());
}create_query_capital.php

Unity

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#

CollectionReference citiesRef = db.Collection("cities");
Query query = citiesRef.WhereEqualTo("Capital", true);
QuerySnapshot querySnapshot = await query.GetSnapshotAsync();
foreach (DocumentSnapshot documentSnapshot in querySnapshot.Documents)
{
    Console.WriteLine("Document {0} returned by query Capital=true", documentSnapshot.Id);
}Program.cs

Ruby

cities_ref = firestore.col collection_path

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

query.get do |city|
  puts "Document #{city.document_id} returned by query capital=true."
endquery_data.rb

执行查询

创建查询对象后，使用 get() 函数检索结果：

Web

db.collection("cities").where("capital", "==", true)
    .get()
    .then((querySnapshot) => {
        querySnapshot.forEach((doc) => {
            // doc.data() is never undefined for query doc snapshots
            console.log(doc.id, " => ", doc.data());
        });
    })
    .catch((error) => {
        console.log("Error getting documents: ", error);
    });test.firestore.js

Swift

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())")
            }
        }
}ViewController.swift

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);
        }
      }
    }];ViewController.m

Java
Android

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

Kotlin+KTX
Android

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

Java

//asynchronously retrieve multiple documents
ApiFuture<QuerySnapshot> future =
    db.collection("cities").whereEqualTo("capital", true).get();
// future.get() blocks on response
List<QueryDocumentSnapshot> documents = future.get().getDocuments();
for (DocumentSnapshot document : documents) {
  System.out.println(document.getId() + " => " + document.toObject(City.class));
}RetrieveDataSnippets.java

Python

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

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

C++

db->Collection("cities")
    .WhereEqualTo("capital", FieldValue::Boolean(true))
    .Get()
    .OnCompletion([](const Future<QuerySnapshot>& future) {
      if (future.error() == Error::kErrorOk) {
        for (const DocumentSnapshot& document :
             future.result()->documents()) {
          std::cout << document << '\n';
        }
      } else {
        std::cout << "Error getting documents: " << future.error_message()
                  << '\n';
      }
    });snippets.cpp

Node.js

const citiesRef = db.collection('cities');
const snapshot = await citiesRef.where('capital', '==', true).get();
if (snapshot.empty) {
  console.log('No matching documents.');
  return;
}

snapshot.forEach(doc => {
  console.log(doc.id, '=>', doc.data());
});index.js

Go

fmt.Println("All capital cities:")
iter := client.Collection("cities").Where("capital", "==", true).Documents(ctx)
for {
	doc, err := iter.Next()
	if err == iterator.Done {
		break
	}
	if err != nil {
		return err
	}
	fmt.Println(doc.Data())
}retrieve.go

PHP

$citiesRef = $db->collection('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, $snapshot->id());
    }
}get_multiple_docs.php

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("");
}Program.cs

Ruby

cities_ref = firestore.col collection_path

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

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

如需详细了解如何检索查询结果，请参阅获取数据。您还可以向查询中添加监听器，以获取当前结果并监听以后的更新。

查询运算符

where() 方法使用三个参数：作为过滤依据的字段、比较运算符和值。Firestore 支持以下比较运算符：

< 小于
<= 小于或等于
== 等于
> 大于
>= 大于或等于
!= 不等于
array-contains
array-contains-any
in
not-in

例如：

Web

citiesRef.where("state", "==", "CA");
citiesRef.where("population", "<", 100000);
citiesRef.where("name", ">=", "San Francisco");test.firestore.js

Swift

citiesRef.whereField("state", isEqualTo: "CA")
citiesRef.whereField("population", isLessThan: 100000)
citiesRef.whereField("name", isGreaterThanOrEqualTo: "San Francisco")ViewController.swift

Objective-C

[citiesRef queryWhereField:@"state" isEqualTo:@"CA"];
[citiesRef queryWhereField:@"population" isLessThan:@100000];
[citiesRef queryWhereField:@"name" isGreaterThanOrEqualTo:@"San Francisco"];ViewController.m

Java
Android

citiesRef.whereEqualTo("state", "CA");
citiesRef.whereLessThan("population", 100000);
citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco");DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereEqualTo("state", "CA")
citiesRef.whereLessThan("population", 100000)
citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco")DocSnippets.kt

Java

Query stateQuery = cities.whereEqualTo("state", "CA");
Query populationQuery = cities.whereLessThan("population", 1000000L);
Query nameQuery = cities.whereGreaterThanOrEqualTo("name", "San Francisco");QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

cities_ref.where(u'state', u'==', u'CA')
cities_ref.where(u'population', u'<', 1000000)
cities_ref.where(u'name', u'>=', u'San Francisco')snippets.py

C++

cities_ref.WhereEqualTo("state", FieldValue::String("CA"));
cities_ref.WhereLessThan("population", FieldValue::Integer(100000));
cities_ref.WhereGreaterThanOrEqualTo("name",
                                     FieldValue::String("San Francisco"));snippets.cpp

Node.js

const stateQueryRes = await citiesRef.where('state', '==', 'CA').get();
const populationQueryRes = await citiesRef.where('population', '<', 1000000).get();
const nameQueryRes = await citiesRef.where('name', '>=', 'San Francisco').get();index.js

Go

countryQuery := cities.Where("state", "==", "CA")
popQuery := cities.Where("population", "<", 1000000)
cityQuery := cities.Where("name", ">=", "San Francisco")query.go

PHP

$stateQuery = $citiesRef->where('state', '=', 'CA');
$populationQuery = $citiesRef->where('population', '>', 1000000);
$nameQuery = $citiesRef->where('name', '>=', 'San Francisco');simple_queries.php

Unity

Query stateQuery = citiesRef.WhereEqualTo("State", "CA");
Query populationQuery = citiesRef.WhereGreaterThan("Population", 1000000);
Query nameQuery = citiesRef.WhereGreaterThanOrEqualTo("Name", "San Francisco");

C#

Query stateQuery = citiesRef.WhereEqualTo("State", "CA");
Query populationQuery = citiesRef.WhereGreaterThan("Population", 1000000);
Query nameQuery = citiesRef.WhereGreaterThanOrEqualTo("Name", "San Francisco");Program.cs

Ruby

state_query      = cities_ref.where "state", "=", "CA"
population_query = cities_ref.where "population", ">", 1_000_000
name_query       = cities_ref.where "name", ">=", "San Francisco"query_data.rb

不等于 (`!=`)

使用不等于 (!=) 运算符返回给定字段存在且不匹配比较值的文档。例如：

Web

citiesRef.where("capital", "!=", false);test.firestore.js

Swift

let notEqualQuery = citiesRef.whereField("capital", isNotEqualTo: false)ViewController.swift

Objective-C

query = [citiesRef queryWhereField:@"capital" isNotEqualTo:@NO];ViewController.m

Java
Android

citiesRef.whereNotEqualTo("capital", false);DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereNotEqualTo("capital", false)DocSnippets.kt

Java

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

Query query = citiesRef.whereNotEqualTo("capital", false);QueryDataSnippets.java

Python

// Snippet not yet available

C++

// Snippet not yet available

Node.js

const capitalNotFalseRes = await citiesRef.where('capital', '!=', false).get();index.js

Go

// Snippet not yet available

PHP

// Snippet not yet available

Unity

// Snippet not yet available

C#

// Snippet not yet available

Ruby

// Snippet not yet available

此查询会返回每一个存在 capital 字段但其值不是 false 或 null 的 city 文档。这包括 capital 字段值等于 true 或者任何 null 以外的非布尔值的 city 文档。

此查询不会返回 capital 字段不存在的 city 文档。不等于 (!=) 和 not-in 查询会排除给定字段不存在的文档。

如果一个字段被设置为任意值，包括空字符串 ("")、null、NaN（非数字），则该字段存在。请注意，null 字段值与 != 子句不匹配，因为 x != null 的计算结果为 undefined。

限制

请注意 != 查询的以下限制：

只有给定字段存在的文档才能与查询匹配。
您不能在复合查询中组合使用 not-in 和 !=。
在复合查询中，范围（<、<=、>、>=）和 != 比较必须针对同一字段进行过滤。

数组成员

您可以使用 array-contains 运算符以根据数组值进行过滤。例如：

Web

citiesRef.where("regions", "array-contains", "west_coast");test.firestore.js

Swift

citiesRef
  .whereField("regions", arrayContains: "west_coast")ViewController.swift

Objective-C

[citiesRef queryWhereField:@"state" arrayContains:@"west_coast"];ViewController.m

Java
Android

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

citiesRef.whereArrayContains("regions", "west_coast");DocSnippets.java

Kotlin+KTX
Android

val citiesRef = db.collection("cities")

citiesRef.whereArrayContains("regions", "west_coast")DocSnippets.kt

Java

CollectionReference citiesRef = db.collection("cities");
Query westCoastQuery = citiesRef.whereArrayContains("regions", "west_coast");QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

query = cities_ref.where(u'regions', u'array_contains', u'west_coast')snippets.py

C++

// This is not yet supported.

Node.js

const westCoastCities = citiesRef.where('regions', 'array-contains',
  'west_coast').get();index.js

Go

query := cities.Where("regions", "array-contains", "west_coast").Documents(ctx)query.go

PHP

$containsQuery = $citiesRef->where('regions', 'array-contains', 'west_coast');array_membership.php

Unity

CollectionReference citiesRef = db.Collection("cities");
Query arrayContainsQuery = citiesRef.WhereArrayContains("region", "west_coast");

C#

Query query = citiesRef.WhereArrayContains("Regions", "west_coast");Program.cs

Ruby

cities_ref = firestore.col collection_path
cities = cities_ref.where "regions", "array-contains", "west_coast"query_data.rb

此查询会返回每一个 regions 字段是包含 west_coast 的数组的 city 文档。对于您查询的值，如果数组具有该值的多个实例，则结果将仅包含该文档一次。

每个查询最多只能使用一个 array-contains 子句。不能组合使用 array-contains 和 array-contains-any。

`in`、`not-in` 和 `array-contains-any`

使用 in 运算符可通过逻辑 OR 在同一字段上结合使用最多 10 个等式 (==) 子句。in 查询会返回给定字段与任意比较值匹配的文档。例如：

Web

citiesRef.where('country', 'in', ['USA', 'Japan']);test.firestore.js

Swift

let citiesRef = db.collection("cities")

citiesRef.whereField("country", in: ["USA", "Japan"])ViewController.swift

Objective-C

FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"];

[citiesRef queryWhereField:@"country" in:@[@"USA", @"Japan"]];ViewController.m

Java
Android

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

citiesRef.whereIn("country", Arrays.asList("USA", "Japan"));DocSnippets.java

Kotlin+KTX
Android

val citiesRef = db.collection("cities")

citiesRef.whereIn("country", listOf("USA", "Japan"))DocSnippets.kt

Java

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

Query query = citiesRef.whereIn("country", Arrays.asList("USA", "Japan"));QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

query = cities_ref.where(u'country', u'in', [u'USA', u'Japan'])
return querysnippets.py

C++

// This is not yet supported.

Node.js

const usaOrJapan = await citiesRef.where('country', 'in', ['USA', 'Japan']).get();index.js

Go

cities := client.Collection("cities")
query := cities.Where("country", "in", []string{"USA", "Japan"}).Documents(ctx)query.go

PHP

// Snippet not yet available

Unity

CollectionReference citiesRef = db.Collection("cities");
List countriesList = new List<object>() {"USA", "Japan"};

Query whereInQuery = citiesRef.WhereIn("country", contriesList);

C#

Query query = citiesRef.WhereIn("Country", new[] { "USA", "Japan" });Program.cs

Ruby

cities_ref = firestore.col collection_path
usr_or_japan = cities_ref.where "country", "in", ["USA", "Japan"]query_data.rb

此查询会返回 country 字段设置为 USA 或 Japan 的每个 city 文档。根据示例数据，这包括 SF、LA、DC 和 TOK 文档。

`not-in`

使用 not-in 运算符可将同一字段上的最多 10 个不等于 (!=) 子句与逻辑 AND 进行组合。not-in 查询返回符合以下条件的文档：给定字段存在但不是 null，并且不匹配任何比较值。例如：

Web

citiesRef.where('country', 'not-in', ['USA', 'Japan']);test.firestore.js

Swift

citiesRef.whereField("country", notIn: ["USA", "Japan"])ViewController.swift

Objective-C

[citiesRef queryWhereField:@"country" notIn:@[@"USA", @"Japan"]];ViewController.m

Java
Android

citiesRef.whereNotIn("country", Arrays.asList("USA", "Japan"));DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereNotIn("country", listOf("USA", "Japan"))DocSnippets.kt

Java

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

Query query = citiesRef.whereNotIn("country", Arrays.asList("USA", "Japan"));QueryDataSnippets.java

Python

// Snippet not yet available

C++

// Snippet not yet available

Node.js

const notUsaOrJapan = await citiesRef.where('country', 'not-in', ['USA', 'Japan']).get();index.js

Go

// Snippet not yet available

PHP

// Snippet not yet available

Unity

// Snippet not yet available

C#

// Snippet not yet available

Ruby

// Snippet not yet available

此查询会返回每一个 country 字段存在并且未设置为 USA、Japan 或 null 的 city 文档。根据示例数据，这包括 London 和 Hong Kong 文档。

not-in 查询会排除给定字段不存在的文档。如果一个字段被设置为任意值，包括空字符串 ("")、null、NaN（非数字），则该字段存在。请注意，x != null 的求值结果为 undefined。使用 null 作为比较值之一的 not-in 查询不匹配任何文档。

`array-contains-any`

使用 array-contains-any 运算符可通过逻辑 OR 在同一字段上结合使用最多 10 个 array-contains 子句。array-contains-any 查询会返回给定字段是包含一个或多个比较值的数组的文档：

Web

citiesRef.where('regions', 'array-contains-any',
    ['west_coast', 'east_coast']);test.firestore.js

Swift

let citiesRef = db.collection("cities")
citiesRef.whereField("regions", arrayContainsAny: ["west_coast", "east_coast"])ViewController.swift

Objective-C

FIRCollectionReference *citiesRef = [self.db collectionWithPath:@"cities"];

[citiesRef queryWhereField:@"regions" arrayContainsAny:@[@"west_coast", @"east_coast"]];ViewController.m

Java
Android

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

citiesRef.whereArrayContainsAny("regions", Arrays.asList("west_coast", "east_coast"));DocSnippets.java

Kotlin+KTX
Android

val citiesRef = db.collection("cities")

citiesRef.whereArrayContainsAny("regions", listOf("west_coast", "east_coast"))DocSnippets.kt

Java

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

Query query =
    citiesRef.whereArrayContainsAny("regions", Arrays.asList("west_coast", "east_coast"));QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

query = cities_ref.where(
    u'regions', u'array_contains_any', [u'west_coast', u'east_coast']
)
return querysnippets.py

C++

// This is not yet supported.

Node.js

const coastalCities = await citiesRef.where('regions', 'array-contains-any',
    ['west_coast', 'east_coast']).get();index.js

Go

cities := client.Collection("cities")
query := cities.Where("regions", "array-contains-any", []string{"west_coast", "east_coast"}).Documents(ctx)query.go

PHP

// Snippet not yet available

Unity

CollectionReference citiesRef = db.Collection("cities");
List regionsList = new List<object>() {"west_coast", "east_coast"};

Query arrayContainsAnyQuery = citiesRef.WhereArrayContainsAny("regions", regionsList);

C#

Query query = citiesRef.WhereArrayContainsAny("Regions", new[] { "west_coast", "east_coast" });Program.cs

Ruby

cities_ref = firestore.col collection_path
costal_cities = cities_ref.where "regions", "array-contains-any", ["west_coast", "east_coast"]query_data.rb

此查询会返回每一个 region 字段是包含 west_coast 或 east_coast 的数组的 city 文档。根据示例数据，这包括 SF、LA 和 DC 文档。

来自 array-contains-any 的结果会被去重。即使文档的数组字段匹配多个比较值，结果集也仅包含该文档一次。

array-contains-any 始终按数组数据类型进行过滤。例如，上面的查询不会返回 region 字段不是数组而是字符串 west_coast 的 city 文档。

您可以将数组值用作 in 的比较值，但与 array-contains-any 不同，子句查找的是与数组长度、顺序和值完全匹配项。例如：

Web

citiesRef.where('region', 'in',
    [['west_coast', 'east_coast']]);test.firestore.js

Swift

citiesRef.whereField("regions", in: [["west_coast"], ["east_coast"]]);ViewController.swift

Objective-C

[citiesRef queryWhereField:@"regions" in:@[@[@"west_coast"], @[@"east_coast"]]];ViewController.m

Java
Android

citiesRef.whereIn("regions", Arrays.asList(new String[]{"west_coast"}, new String[]{"east_coast"}));DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereIn("regions", listOf(arrayOf("west_coast"), arrayOf("east_coast")))DocSnippets.kt

Java

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

Query query =
    citiesRef.whereIn(
        "regions", Arrays.asList(Arrays.asList("west_coast"), Arrays.asList("east_coast")));QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

query = cities_ref.where(
    u'regions', u'in', [[u'west_coast'], [u'east_coast']]
)
return querysnippets.py

C++

// This is not yet supported.

Node.js

const exactlyOneCoast = await citiesRef.where('region', 'in',
    [['west_coast', 'east_coast']]).get();index.js

Go

cities := client.Collection("cities")
query := cities.Where("regions", "in", [][]string{{"west_coast"}, {"east_coast"}}).Documents(ctx)query.go

PHP

// Snippet not yet available

Unity

// Not yet supported in the Unity SDK

C#

Query query = citiesRef.WhereIn("Regions",
    new[] { new[] { "west_coast" }, new[] { "east_coast" } });Program.cs

Ruby

cities_ref = firestore.col collection_path
exactly_one_cost = cities_ref.where "regions", "in", [["west_coast"], ["east_coast"]]query_data.rb

此查询会返回每个 region 字段是仅包含一个元素（west_coast 或 east_coast）的数组的 city 文档。在示例数据中，只有 DC 文档符合条件，因为其 region 字段为 ["east_coast"]。但是，SF 文档不匹配，因为其 region 字段为 ["west_coast", "norcal"]。

限制

请注意 in、not-in 和 array-contains-any 的以下限制：

in、not-in 和 array-contains-any 最多支持 10 个比较值。
每个查询最多只能使用一个 array-contains 子句。不能组合使用 array-contains 和 array-contains-any。
每个查询最多只能使用一个 in、not-in 或 array-contains-any 子句。不能在同一查询中组合这些运算符。
不能组合使用 not-in 和不等于 !=。
不能按等式 (==) 或 in 子句中包含的字段对查询进行排序。

复合查询

您可以串连多个等式运算符（== 或 array-contains）方法以创建更具体的查询（逻辑 AND）。但是，要将等式运算符与不等式运算符 <、<=、>、!= 组合使用，您必须创建复合索引。

Web

citiesRef.where("state", "==", "CO").where("name", "==", "Denver");
citiesRef.where("state", "==", "CA").where("population", "<", 1000000);test.firestore.js

Swift

citiesRef
    .whereField("state", isEqualTo: "CO")
    .whereField("name", isEqualTo: "Denver")
citiesRef
    .whereField("state", isEqualTo: "CA")
    .whereField("population", isLessThan: 1000000)ViewController.swift

Objective-C

[[citiesRef queryWhereField:@"state" isEqualTo:@"CO"]
    queryWhereField:@"name" isGreaterThanOrEqualTo:@"Denver"];
[[citiesRef queryWhereField:@"state" isEqualTo:@"CA"]
    queryWhereField:@"population" isLessThan:@1000000];ViewController.m

Java
Android

citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver");
citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000);DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver")
citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000)DocSnippets.kt

Java

Query chainedQuery1 = cities.whereEqualTo("state", "CO").whereEqualTo("name", "Denver");
Query chainedQuery2 = cities.whereEqualTo("state", "CA").whereLessThan("population", 1000000L);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')

denver_query = cities_ref.where(
    u'state', u'==', u'CO').where(u'name', u'==', u'Denver')
large_us_cities_query = cities_ref.where(
    u'state', u'==', u'CA').where(u'population', u'>', 1000000)snippets.py

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));snippets.cpp

Node.js

citiesRef.where('state', '==', 'CO').where('name', '==', 'Denver');
citiesRef.where('state', '==', 'CA').where('population', '<', 1000000);index.js

Go

denverQuery := cities.Where("name", "==", "Denver").Where("state", "==", "CO")
caliQuery := cities.Where("state", "==", "CA").Where("population", "<=", 1000000)
query := cities.Where("country", "==", "USA").Where("population", ">", 5000000)query.go

PHP

$chainedQuery = $citiesRef
    ->where('state', '=', 'CA')
    ->where('name', '=', 'San Francisco');chained_query.php
$chainedQuery = $citiesRef
    ->where('state', '=', 'CA')
    ->where('population', '<', 1000000);composite_index_chained_query.php

Unity

Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereEqualTo("Name", "San Francisco");
Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereLessThan("Population", 1000000);

C#

Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereEqualTo("Name", "San Francisco");Program.cs
Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereLessThan("Population", 1000000);Program.cs

Ruby

chained_query = cities_ref.where("state", "=", "CA").where("name", "=", "San Francisco")query_data.rb
chained_query = cities_ref.where("state", "=", "CA").where("population", "<", 1_000_000)query_data.rb

只能对单个字段执行范围（<、<=、>、>=）或不等于 (!=) 比较，并且一个复合查询中最多只能包含一个 array-contains 或 array-contains-any 子句：

有效：范围过滤器仅针对一个字段

Web

citiesRef.where("state", ">=", "CA").where("state", "<=", "IN");
citiesRef.where("state", "==", "CA").where("population", ">", 1000000);test.firestore.js

Swift

citiesRef
    .whereField("state", isGreaterThanOrEqualTo: "CA")
    .whereField("state", isLessThanOrEqualTo: "IN")
citiesRef
    .whereField("state", isEqualTo: "CA")
    .whereField("population", isGreaterThan: 1000000)ViewController.swift

Objective-C

[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"]
    queryWhereField:@"state" isLessThanOrEqualTo:@"IN"];
[[citiesRef queryWhereField:@"state" isEqualTo:@"CA"]
    queryWhereField:@"population" isGreaterThan:@1000000];ViewController.m

Java
Android

citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereLessThanOrEqualTo("state", "IN");
citiesRef.whereEqualTo("state", "CA")
        .whereGreaterThan("population", 1000000);DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereLessThanOrEqualTo("state", "IN")
citiesRef.whereEqualTo("state", "CA")
        .whereGreaterThan("population", 1000000)DocSnippets.kt

Java

Query validQuery1 =
    cities.whereGreaterThanOrEqualTo("state", "CA").whereLessThanOrEqualTo("state", "IN");
Query validQuery2 = cities.whereEqualTo("state", "CA").whereGreaterThan("population", 1000000);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
cities_ref.where(u'state', u'>=', u'CA').where(u'state', u'<=', u'IN')snippets.py

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));snippets.cpp

Node.js

citiesRef.where('state', '>=', 'CA').where('state', '<=', 'IN');
citiesRef.where('state', '==', 'CA').where('population', '>', 1000000);index.js

Go

stateQuery := cities.Where("state", ">=", "CA").Where("state", "<", "IN")
populationQuery := cities.Where("state", "==", "CA").Where("population", ">", 1000000)query.go

PHP

$rangeQuery = $citiesRef
    ->where('state', '>=', 'CA')
    ->where('state', '<=', 'IN');range_query.php

Unity

Query rangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereLessThanOrEqualTo("State", "IN");

C#

Query rangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereLessThanOrEqualTo("State", "IN");Program.cs

Ruby

range_query = cities_ref.where("state", ">=", "CA").where("state", "<=", "IN")query_data.rb

无效：范围过滤器针对的是不同字段

Web

citiesRef.where("state", ">=", "CA").where("population", ">", 100000);test.firestore.js

Swift

citiesRef
    .whereField("state", isGreaterThanOrEqualTo: "CA")
    .whereField("population", isGreaterThan: 1000000)ViewController.swift

Objective-C

[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"]
    queryWhereField:@"population" isGreaterThan:@1000000];ViewController.m

Java
Android

citiesRef.whereGreaterThanOrEqualTo("state", "CA").whereGreaterThan("population", 100000);DocSnippets.java

Kotlin+KTX
Android

citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereGreaterThan("population", 100000)DocSnippets.kt

Java

Query invalidRangeQuery =
    cities.whereGreaterThanOrEqualTo("state", "CA").whereGreaterThan("population", 100000);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
cities_ref.where(
    u'state', u'>=', u'CA').where(u'population', u'>=', 1000000)snippets.py

C++

// BAD EXAMPLE -- will crash the program:
cities_ref.WhereGreaterThanOrEqualTo("state", FieldValue::String("CA"))
    .WhereGreaterThan("population", FieldValue::Integer(100000));snippets.cpp

Node.js

citiesRef.where('state', '>=', 'CA').where('population', '>', 1000000);index.js

Go

query := cities.Where("state", ">=", "CA").Where("population", ">", 1000000)query.go

PHP

$invalidRangeQuery = $citiesRef
    ->where('state', '>=', 'CA')
    ->where('population', '>', 1000000);invalid_range_query.php

Unity

Query invalidRangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereGreaterThan("Population", 1000000);

C#

Query invalidRangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereGreaterThan("Population", 1000000);Program.cs

Ruby

invalid_range_query = cities_ref.where("state", ">=", "CA").where("population", ">", 1_000_000)query_data.rb

集合组查询

集合组由具有相同 ID 的所有集合组成。默认情况下，查询从数据库的单个集合中检索结果。您可以使用集合组查询从集合组（而不是从单个集合）中检索文档。

例如，您可以通过向每个城市添加地标子集来创建 landmarks 集合组：

Web

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'
    })
]);test.firestore.js

Swift

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)ViewController.swift

Objective-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];ViewController.m

Java
Android

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);DocSnippets.java

Kotlin+KTX
Android

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)DocSnippets.kt

Java

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

final List<ApiFuture<WriteResult>> futures =
    Arrays.asList(
        cities
            .document("SF")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Golden Gate Bridge");
                    put("type", "bridge");
                  }
                }),
        cities
            .document("SF")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Legion of Honor");
                    put("type", "museum");
                  }
                }),
        cities
            .document("LA")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Griffith Park");
                    put("type", "park");
                  }
                }),
        cities
            .document("LA")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "The Getty");
                    put("type", "museum");
                  }
                }),
        cities
            .document("DC")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Lincoln Memorial");
                    put("type", "memorial");
                  }
                }),
        cities
            .document("DC")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "National Air and Space Museum");
                    put("type", "museum");
                  }
                }),
        cities
            .document("TOK")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Ueno Park");
                    put("type", "park");
                  }
                }),
        cities
            .document("TOK")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "National Museum of Nature and Science");
                    put("type", "museum");
                  }
                }),
        cities
            .document("BJ")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Jingshan Park");
                    put("type", "park");
                  }
                }),
        cities
            .document("BJ")
            .collection("landmarks")
            .document()
            .set(
                new HashMap<String, String>() {
                  {
                    put("name", "Beijing Ancient Observatory");
                    put("type", "museum");
                  }
                }));
final List<WriteResult> landmarks = ApiFutures.allAsList(futures).get();QueryDataSnippets.java

Python

cities = db.collection(u'cities')

sf_landmarks = cities.document(u'SF').collection(u'landmarks')
sf_landmarks.document().set({
    u'name': u'Golden Gate Bridge',
    u'type': u'bridge'
})
sf_landmarks.document().set({
    u'name': u'Legion of Honor',
    u'type': u'museum'
})
la_landmarks = cities.document(u'LA').collection(u'landmarks')
la_landmarks.document().set({
    u'name': u'Griffith Park',
    u'type': u'park'
})
la_landmarks.document().set({
    u'name': u'The Getty',
    u'type': u'museum'
})
dc_landmarks = cities.document(u'DC').collection(u'landmarks')
dc_landmarks.document().set({
    u'name': u'Lincoln Memorial',
    u'type': u'memorial'
})
dc_landmarks.document().set({
    u'name': u'National Air and Space Museum',
    u'type': u'museum'
})
tok_landmarks = cities.document(u'TOK').collection(u'landmarks')
tok_landmarks.document().set({
    u'name': u'Ueno Park',
    u'type': u'park'
})
tok_landmarks.document().set({
    u'name': u'National Museum of Nature and Science',
    u'type': u'museum'
})
bj_landmarks = cities.document(u'BJ').collection(u'landmarks')
bj_landmarks.document().set({
    u'name': u'Jingshan Park',
    u'type': u'park'
})
bj_landmarks.document().set({
    u'name': u'Beijing Ancient Observatory',
    u'type': u'museum'
})

C++

// This is not yet supported.

Node.js

const citiesRef = db.collection('cities');

await citiesRef.doc('SF').collection('landmarks').doc().set({
  name: 'Golden Gate Bridge',
  type: 'bridge'
});
await citiesRef.doc('SF').collection('landmarks').doc().set({
  name: 'Legion of Honor',
  type: 'museum'
});
await citiesRef.doc('LA').collection('landmarks').doc().set({
  name: 'Griffith Park',
  type: 'park'
});
await citiesRef.doc('LA').collection('landmarks').doc().set({
  name: 'The Getty',
  type: 'museum'
});
await citiesRef.doc('DC').collection('landmarks').doc().set({
  name: 'Lincoln Memorial',
  type: 'memorial'
});
await citiesRef.doc('DC').collection('landmarks').doc().set({
  name: 'National Air and Space Museum',
  type: 'museum'
});
await citiesRef.doc('TOK').collection('landmarks').doc().set({
  name: 'Ueno Park',
  type: 'park'
});
await citiesRef.doc('TOK').collection('landmarks').doc().set({
  name: 'National Museum of Nature and Science',
  type: 'museum'
});
await citiesRef.doc('BJ').collection('landmarks').doc().set({
  name: 'Jingshan Park',
  type: 'park'
});
await citiesRef.doc('BJ').collection('landmarks').doc().set({
  name: 'Beijing Ancient Observatory',
  type: 'museum'
});index.js

Go

import (
	"context"
	"fmt"

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

// collectionGroupSetup sets up a collection group to query.
func collectionGroupSetup(projectID, cityCollection string) error {
	ctx := context.Background()

	client, err := firestore.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("firestore.NewClient: %v", err)
	}
	defer client.Close()

	landmarks := []struct {
		city, name, t string
	}{
		{"SF", "Golden Gate Bridge", "bridge"},
		{"SF", "Legion of Honor", "museum"},
		{"LA", "Griffith Park", "park"},
		{"LA", "The Getty", "museum"},
		{"DC", "Lincoln Memorial", "memorial"},
		{"DC", "National Air and Space Museum", "museum"},
		{"TOK", "Ueno Park", "park"},
		{"TOK", "National Museum of Nature and Science", "museum"},
		{"BJ", "Jingshan Park", "park"},
		{"BJ", "Beijing Ancient Observatory", "museum"},
	}

	cities := client.Collection(cityCollection)
	for _, l := range landmarks {
		if _, err := cities.Doc(l.city).Collection("landmarks").NewDoc().Set(ctx, map[string]string{
			"name": l.name,
			"type": l.t,
		}); err != nil {
			return fmt.Errorf("Set: %v", err)
		}
	}

	return nil
}
collection_group_setup.go

PHP

// Snippet not yet available

Unity

// Not yet supported in the Unity SDK

C#

await citiesRef.Document("SF").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Golden Gate Bridge", Type = "bridge" });
await citiesRef.Document("SF").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Legion of Honor", Type = "museum" });
await citiesRef.Document("LA").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Griffith Park", Type = "park" });
await citiesRef.Document("DC").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Lincoln Memorial", Type = "memorial" });
await citiesRef.Document("DC").Collection("landmarks").Document()
    .CreateAsync(new { Name = "National Air And Space Museum", Type = "museum" });
await citiesRef.Document("TOK").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Ueno Park", Type = "park" });
await citiesRef.Document("TOK").Collection("landmarks").Document()
    .CreateAsync(new { Name = "National Museum of Nature and Science", Type = "museum" });
await citiesRef.Document("BJ").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Jingshan Park", Type = "park" });
await citiesRef.Document("BJ").Collection("landmarks").Document()
    .CreateAsync(new { Name = "Beijing Ancient Observatory", Type = "museum" });Program.cs

Ruby

cities_ref = firestore.col collection_path

sf_landmarks = cities_ref.document("SF").collection("landmarks")
sf_landmarks.document.set(
  name: "Golden Gate Bridge",
  type: "bridge"
)
sf_landmarks.document.set(
  name: "Legion of Honor",
  type: "museum"
)

la_landmarks = cities_ref.document("LA").collection("landmarks")
la_landmarks.document.set(
  name: "Griffith Park",
  type: "park"
)
la_landmarks.document.set(
  name: "The Getty",
  type: "museum"
)

dc_landmarks = cities_ref.document("DC").collection("landmarks")
dc_landmarks.document.set(
  name: "Lincoln Memorial",
  type: "memorial"
)
dc_landmarks.document.set(
  name: "National Air and Space Museum",
  type: "museum"
)

tok_landmarks = cities_ref.document("TOK").collection("landmarks")
tok_landmarks.document.set(
  name: "Ueno Park",
  type: "park"
)
tok_landmarks.document.set(
  name: "National Museum of Nature and Science",
  type: "museum"
)

bj_landmarks = cities_ref.document("BJ").collection("landmarks")
bj_landmarks.document.set(
  name: "Jingshan Park",
  type: "park"
)
bj_landmarks.document.set(
  name: "Beijing Ancient Observatory",
  type: "museum"
)query_data.rb

我们可以使用之前介绍的简单查询和复合查询来查询单个城市的 landmarks 子集合，但您可能还需要同时从每个城市的 landmarks 子集合中检索结果。

landmarks 集合组包含 ID 为 landmarks 的所有集合，您可以使用集合组查询进行查询。例如，此集合组查询会检索所有城市的所有 museum 地标：

Web

var museums = db.collectionGroup('landmarks').where('type', '==', 'museum');
museums.get().then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
        console.log(doc.id, ' => ', doc.data());
    });
});test.firestore.js

Swift

db.collectionGroup("landmarks").whereField("type", isEqualTo: "museum").getDocuments { (snapshot, error) in
    // ...
}ViewController.swift

Objective-C

[[[self.db collectionGroupWithID:@"landmarks"] queryWhereField:@"type" isEqualTo:@"museum"]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
    // ...
}];ViewController.m

Java
Android

db.collectionGroup("landmarks").whereEqualTo("type", "museum").get()
        .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
            @Override
            public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                // ...
            }
        });DocSnippets.java

Kotlin+KTX
Android

db.collectionGroup("landmarks").whereEqualTo("type", "museum").get()
        .addOnSuccessListener { queryDocumentSnapshots ->
            // ...
        }DocSnippets.kt

Java

final Query museums = db.collectionGroup("landmarks").whereEqualTo("type", "museum");
final ApiFuture<QuerySnapshot> querySnapshot = museums.get();
for (DocumentSnapshot document : querySnapshot.get().getDocuments()) {
  System.out.println(document.getId());
}QueryDataSnippets.java

Python

museums = db.collection_group(u'landmarks')\
    .where(u'type', u'==', u'museum')
docs = museums.stream()
for doc in docs:
    print(f'{doc.id} => {doc.to_dict()}')

C++

// This is not yet supported.

Node.js

const querySnapshot = await db.collectionGroup('landmarks').where('type', '==', 'museum').get();
querySnapshot.forEach((doc) => {
  console.log(doc.id, ' => ', doc.data());
});index.js

Go

import (
	"context"
	"fmt"
	"io"

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

// collectionGroupQuery runs a collection group query over the data created by
// collectionGroupSetup.
func collectionGroupQuery(w io.Writer, projectID string) error {
	ctx := context.Background()

	client, err := firestore.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("firestore.NewClient: %v", err)
	}
	defer client.Close()

	it := client.CollectionGroup("landmarks").Where("type", "==", "museum").Documents(ctx)
	for {
		doc, err := it.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return err
		}
		fmt.Fprintf(w, "%s: %s", doc.Ref.ID, doc.Data()["name"])
	}

	return nil
}
collection_group_query.go

PHP

// Snippet not yet available

Unity

// Not yet supported in the Unity SDK

C#

Query museums = db.CollectionGroup("landmarks").WhereEqualTo("Type", "museum");
QuerySnapshot querySnapshot = await museums.GetSnapshotAsync();
foreach (DocumentSnapshot document in querySnapshot.Documents)
{
    Console.WriteLine($"{document.Reference.Path}: {document.GetValue<string>("Name")}");
}Program.cs

Ruby

museums = firestore.collection_group("landmarks").where("type", "==", "museum")
museums.get do |museum|
  puts "#{museum[:type]} name is #{museum[:name]}."
endquery_data.rb

在使用集合组查询之前，您必须创建支持集合组查询的索引。您可以通过错误消息、控制台或 Firebase CLI 创建索引。

对于 Web 和移动 SDK，您还必须创建允许集合组查询的规则。

查询限制

以下列表总结了 Firestore 查询的限制：

Firestore 对逻辑 OR 查询提供有限的支持。in 和 array-contains-any 运算符支持单个字段上最多有 10 个等式 (==) 或 array-contains 条件的逻辑 OR。在这种情况下，请为每个 OR 条件创建一个单独的查询，并在应用中合并查询结果。
在复合查询中，范围（<、<=、>、>=）和不等于 (!=) 比较必须对同一字段进行过滤。
每个查询最多只能使用一个 array-contains 子句。不能组合使用 array-contains 和 array-contains-any。
每个查询最多只能使用一个 in、not-in 或 array-contains-any 子句。不能在同一查询中组合使用 in、not-in 和 array-contains-any。
不能按等式 (==) 或 in 子句中包含的字段对查询进行排序。

查询和过滤数据

示例数据

Web

Swift

Objective-C

JavaAndroid

Kotlin+KTXAndroid

Java

Python

C++

Node.js

Go

PHP

Unity

C#

Ruby

简单查询

Web

Swift

Objective-C

JavaAndroid

Kotlin+KTXAndroid

Java

Python

C++

Node.js

Go

PHP

Unity

C#

Ruby

Web

Swift

Objective-C

JavaAndroid

Kotlin+KTXAndroid

Java

Python

C++

Node.js

Go

PHP

Unity

C#

Ruby

执行查询

Web

Swift

Objective-C

JavaAndroid

Kotlin+KTXAndroid

Java

Python

C++

Node.js

Go

PHP

Unity

C#

Ruby

查询运算符

Web

Swift

Objective-C

JavaAndroid

Kotlin+KTXAndroid

Java

Python

C++

Node.js

Go

PHP

Unity

C#

Ruby

不等于 (!=)

Web

Swift

Objective-C

JavaAndroid

Java
Android

Kotlin+KTX
Android

Java
Android

Kotlin+KTX
Android

Java
Android

Kotlin+KTX
Android

Java
Android

Kotlin+KTX
Android

Java
Android

Kotlin+KTX
Android

不等于 (`!=`)

Java
Android

Kotlin+KTX
Android

Java
Android

Kotlin+KTX
Android

`in`、`not-in` 和 `array-contains-any`

Java
Android

Kotlin+KTX
Android

`not-in`

Java
Android

Kotlin+KTX
Android

`array-contains-any`

Java
Android

Kotlin+KTX
Android