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在 Cloud Firestore 中执行简单查询和复合查询

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

示例数据

首先,请编写一些关于城市的数据,以便我们确定读回这些数据的不同方式:

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"] });
Swift
let citiesRef = db.collection("cities")

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

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

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

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

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

Map<String, Object> data5 = new HashMap<>();
data5.put("name", "Beijing");
data5.put("state", null);
data5.put("country", "China");
data5.put("capital", true);
data5.put("population", 21500000);
data5.put("regions", Arrays.asList("jingjinji", "hebei"));
cities.document("BJ").set(data5);
Kotlin
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");
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();
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(
            u'City(name={}, country={}, population={}, capital={}, regions={})'
            .format(self.name, self.country, self.population, self.capital,
                    self.regions))
cities_ref = db.collection(u'cities')
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())
cities_ref.document(u'BJ').set(
    City(u'Beijing', None, u'China', True, 21500000, [u'hebei']).to_dict())
Node.js
let citiesRef = db.collection('cities');

let setSf = citiesRef.doc('SF').set({
  name: 'San Francisco', state: 'CA', country: 'USA',
  capital: false, population: 860000,
  regions: ['west_coast', 'norcal']
});
let setLa = citiesRef.doc('LA').set({
  name: 'Los Angeles', state: 'CA', country: 'USA',
  capital: false, population: 3900000,
  regions: ['west_coast', 'socal']
});
let setDc = citiesRef.doc('DC').set({
  name: 'Washington, D.C.', state: null, country: 'USA',
  capital: true, population: 680000,
  regions: ['east_coast']
});
let setTok = citiesRef.doc('TOK').set({
  name: 'Tokyo', state: null, country: 'Japan',
  capital: true, population: 9000000,
  regions: ['kanto', 'honshu']
});
let setBj = citiesRef.doc('BJ').set({
  name: 'Beijing', state: null, country: 'China',
  capital: true, population: 21500000,
  regions: ['jingjinji', 'hebei']
});
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
	}
}
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);
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.");
Ruby
cities_ref = firestore.col "cities"
cities_ref.doc("SF").set(
  name:       "San Francisco",
  state:      "CA",
  country:    "USA",
  capital:    false,
  population: 860_000
)
cities_ref.doc("LA").set(
  name:       "Los Angeles",
  state:      "CA",
  country:    "USA",
  capital:    false,
  population: 3_900_000
)
cities_ref.doc("DC").set(
  name:       "Washington D.C.",
  state:      nil,
  country:    "USA",
  capital:    true,
  population: 680_000
)
cities_ref.doc("TOK").set(
  name:       "Tokyo",
  state:      nil,
  country:    "Japan",
  capital:    true,
  population: 9_000_000
)
cities_ref.doc("BJ").set(
  name:       "Beijing",
  state:      nil,
  country:    "China",
  capital:    true,
  population: 21_500_000
)

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");
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")
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"];
  
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");
Kotlin
// 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 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());
}
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')
Node.js
// Create a reference to the cities collection
let citiesRef = db.collection('cities');

// Create a query against the collection
let queryRef = citiesRef.where('state', '==', 'CA');
Go
query := client.Collection("cities").Where("state", "==", "CA")
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());
}
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);
}
Ruby
cities_ref = firestore.col "cities"

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

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

以下查询会返回美国的首都和美国的所有首府:

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

var query = citiesRef.where("capital", "==", true);
Swift
let capitalCities = db.collection("cities").whereField("capital", isEqualTo: true)
Objective-C
FIRQuery *capitalCities =
    [[self.db collectionWithPath:@"cities"] queryWhereField:@"capital" isEqualTo:@YES];
  
Java
Query capitalCities = db.collection("cities").whereEqualTo("capital", true);
Kotlin
val capitalCities = db.collection("cities").whereEqualTo("capital", true)
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());
}
Python
cities_ref = db.collection(u'cities')

query = cities_ref.where(u'capital', u'==', True)
Node.js
// Create a reference to the cities collection
let citiesRef = db.collection('cities');

// Create a query against the collection
let queryRef = citiesRef.where('capital', '==', true);
Go
query := client.Collection("cities").Where("capital", "==", true)
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());
}
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);
}
Ruby
cities_ref = firestore.col "cities"

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

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

执行查询

创建查询对象后,请使用 get() 函数检索结果:

Web
db.collection("cities").where("capital", "==", true)
    .get()
    .then(function(querySnapshot) {
        querySnapshot.forEach(function(doc) {
            // doc.data() is never undefined for query doc snapshots
            console.log(doc.id, " => ", doc.data());
        });
    })
    .catch(function(error) {
        console.log("Error getting documents: ", error);
    });
Swift
db.collection("cities").whereField("capital", isEqualTo: true)
    .getDocuments() { (querySnapshot, err) in
        if let err = err {
            print("Error getting documents: \(err)")
        } else {
            for document in querySnapshot!.documents {
                print("\(document.documentID) => \(document.data())")
            }
        }
}
Objective-C
[[[self.db collectionWithPath:@"cities"] queryWhereField:@"capital" isEqualTo:@(YES)]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
      if (error != nil) {
        NSLog(@"Error getting documents: %@", error);
      } else {
        for (FIRDocumentSnapshot *document in snapshot.documents) {
          NSLog(@"%@ => %@", document.documentID, document.data);
        }
      }
    }];
  
Java
db.collection("cities")
        .whereEqualTo("capital", true)
        .get()
        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, document.getId() + " => " + document.getData());
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.getException());
                }
            }
        });
Kotlin
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
//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));
}
Python
docs = db.collection(u'cities').where(u'capital', u'==', True).stream()

for doc in docs:
    print(u'{} => {}'.format(doc.id, doc.to_dict()))
Node.js
let citiesRef = db.collection('cities');
let query = citiesRef.where('capital', '==', true).get()
  .then(snapshot => {
    if (snapshot.empty) {
      console.log('No matching documents.');
      return;
    }

    snapshot.forEach(doc => {
      console.log(doc.id, '=>', doc.data());
    });
  })
  .catch(err => {
    console.log('Error getting documents', err);
  });
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())
}
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());
    }
}
C#
Query capitalQuery = db.Collection("cities").WhereEqualTo("Capital", true);
QuerySnapshot capitalQuerySnapshot = await capitalQuery.GetSnapshotAsync();
foreach (DocumentSnapshot documentSnapshot in capitalQuerySnapshot.Documents)
{
    if (documentSnapshot.Exists)
    {
        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("");
    }
    else
    {
        Console.WriteLine("Document {0} does not exist!", documentSnapshot.Id);
    }
}
Ruby
cities_ref = firestore.col "cities"

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

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

如需详细了解如何检索查询结果,请参阅获取数据。您还可以向查询添加侦听器,以获取当前结果并侦听未来更新。

查询运算符

where() 方法会传递三个参数:作为过滤依据的字段、比较运算符和值。比较运算符可以是 <<===>>=array-contains。对于 iOS、Android 和 Java,比较运算符会在方法中明确指定。

下面是一些示例过滤条件:

Web
citiesRef.where("state", "==", "CA")
citiesRef.where("population", "<", 100000)
citiesRef.where("name", ">=", "San Francisco")
Swift
citiesRef.whereField("state", isEqualTo: "CA")
citiesRef.whereField("population", isLessThan: 100000)
citiesRef.whereField("name", isGreaterThanOrEqualTo: "San Francisco")
Objective-C
[citiesRef queryWhereField:@"state" isEqualTo:@"CA"];
[citiesRef queryWhereField:@"population" isLessThan:@100000];
[citiesRef queryWhereField:@"name" isGreaterThanOrEqualTo:@"San Francisco"];
  
Java
citiesRef.whereEqualTo("state", "CA");
citiesRef.whereLessThan("population", 100000);
citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco");
Kotlin
citiesRef.whereEqualTo("state", "CA")
citiesRef.whereLessThan("population", 100000)
citiesRef.whereGreaterThanOrEqualTo("name", "San Francisco")
Java
Query stateQuery = cities.whereEqualTo("state", "CA");
Query populationQuery = cities.whereLessThan("population", 1000000L);
Query nameQuery = cities.whereGreaterThanOrEqualTo("name", "San Francisco");
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')
Node.js
let stateQuery = citiesRef.where('state', '==', 'CA');
let populationQuery = citiesRef.where('population', '<', 1000000);
let nameQuery = citiesRef.where('name', '>=', 'San Francisco');
Go
countryQuery := cities.Where("state", "==", "CA")
popQuery := cities.Where("population", "<", 1000000)
cityQuery := cities.Where("name", ">=", "San Francisco")
PHP
$stateQuery = $citiesRef->where('state', '=', 'CA');
$populationQuery = $citiesRef->where('population', '>', 1000000);
$nameQuery = $citiesRef->where('name', '>=', 'San Francisco');
C#
Query stateQuery = citiesRef.WhereEqualTo("State", "CA");
Query populationQuery = citiesRef.WhereGreaterThan("Population", 1000000);
Query nameQuery = citiesRef.WhereGreaterThanOrEqualTo("Name", "San Francisco");
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"

数组成员

您可以使用 array-contains 运算符根据数组值进行过滤。例如:

Web
citiesRef.where("regions", "array-contains", "west_coast")
Swift
citiesRef
  .whereField("regions", arrayContains: "west_coast")
Objective-C
[citiesRef queryWhereField:@"state" arrayContains:@"west_coast"];
  
Java
CollectionReference citiesRef = db.collection("cities");

citiesRef.whereArrayContains("regions", "west_coast");
Kotlin
val citiesRef = db.collection("cities")

citiesRef.whereArrayContains("regions", "west_coast")
Java
CollectionReference citiesRef = db.collection("cities");
Query westCoastQuery = citiesRef.whereArrayContains("regions", "west_coast");
Python
cities_ref = db.collection(u'cities')

query = cities_ref.where(u'regions', u'array_contains', u'west_coast')
Node.js
let westCoastCities = citiesRef.where('regions', 'array-contains',
  'west_coast');
Go
query := cities.Where("regions", "array-contains", "west_coast").Documents(ctx)
PHP
$containsQuery = $citiesRef->where('regions', 'array-contains', 'west_coast');
C#
Query query = citiesRef.WhereArrayContains("Regions", "west_coast");
Ruby
// Not supported yet

此查询会返回每个 city 文档,其中 regions 字段是包含 west_coast 的数组。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。

复合查询

您还可以链接多个 where() 方法来创建更具体的查询(逻辑 AND)。但是,要将等式运算符 (==) 与范围运算符或 array-contains 子句(<<=>>=array-contains)结合使用,请务必创建复合索引

Web
citiesRef.where("state", "==", "CO").where("name", "==", "Denver")
citiesRef.where("state", "==", "CA").where("population", "<", 1000000)
Swift
citiesRef
    .whereField("state", isEqualTo: "CO")
    .whereField("name", isEqualTo: "Denver")
citiesRef
    .whereField("state", isEqualTo: "CA")
    .whereField("population", isLessThan: 1000000)
Objective-C
[[citiesRef queryWhereField:@"state" isEqualTo:@"CO"]
    queryWhereField:@"name" isGreaterThanOrEqualTo:@"Denver"];
[[citiesRef queryWhereField:@"state" isEqualTo:@"CA"]
    queryWhereField:@"population" isLessThan:@1000000];
  
Java
citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver");
citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000);
Kotlin
citiesRef.whereEqualTo("state", "CO").whereEqualTo("name", "Denver")
citiesRef.whereEqualTo("state", "CA").whereLessThan("population", 1000000)
Java
Query chainedQuery1 = cities.whereEqualTo("state", "CO")
    .whereEqualTo("name", "Denver");Query chainedQuery2 = cities.whereEqualTo("state", "CA")
    .whereLessThan("population", 1000000L);
Python
cities_ref = db.collection(u'cities')

sydney_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)
Node.js
citiesRef.where('state', '==', 'CO').where('name', '==', 'Denver');citiesRef.where('state', '==', 'CA').where('population', '<', 1000000);
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)
PHP
$chainedQuery = $citiesRef
    ->where('state', '=', 'CA')
    ->where('name', '=', 'San Francisco');
$chainedQuery = $citiesRef
    ->where('state', '=', 'CA')
    ->where('population', '<', 1000000);
C#
Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereEqualTo("Name", "San Francisco");
Query chainedQuery = citiesRef
    .WhereEqualTo("State", "CA")
    .WhereLessThan("Population", 1000000);
Ruby
chained_query = cities_ref.where("state", "=", "CA").where("name", "=", "San Francisco")
chained_query = cities_ref.where("state", "=", "CA").where("population", "<", 1_000_000)

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

有效:范围过滤条件仅针对一个字段

Web
citiesRef.where("state", ">=", "CA").where("state", "<=", "IN")
citiesRef.where("state", "==", "CA").where("population", ">", 1000000)
Swift
citiesRef
    .whereField("state", isGreaterThanOrEqualTo: "CA")
    .whereField("state", isLessThanOrEqualTo: "IN")
citiesRef
    .whereField("state", isEqualTo: "CA")
    .whereField("population", isGreaterThan: 1000000)
Objective-C
[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"]
    queryWhereField:@"state" isLessThanOrEqualTo:@"IN"];
[[citiesRef queryWhereField:@"state" isEqualTo:@"CA"]
    queryWhereField:@"population" isGreaterThan:@1000000];
  
Java
citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereLessThanOrEqualTo("state", "IN");
citiesRef.whereEqualTo("state", "CA")
        .whereGreaterThan("population", 1000000);
Kotlin
citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereLessThanOrEqualTo("state", "IN")
citiesRef.whereEqualTo("state", "CA")
        .whereGreaterThan("population", 1000000)
Java
Query validQuery1 = cities.whereGreaterThanOrEqualTo("state", "CA")
    .whereLessThanOrEqualTo("state", "IN");
Query validQuery2 = cities.whereEqualTo("state", "CA")
    .whereGreaterThan("population", 1000000);
Python
cities_ref = db.collection(u'cities')
cities_ref.where(u'state', u'>=', u'CA').where(u'state', u'<=', u'IN')
Node.js
citiesRef.where('state', '>=', 'CA').where('state', '<=', 'IN');
citiesRef.where('state', '==', 'CA').where('population', '>', 1000000);
Go
stateQuery := cities.Where("state", ">=", "CA").Where("state", "<", "IN")
populationQuery := cities.Where("state", "==", "CA").Where("population", ">", 1000000)
PHP
$rangeQuery = $citiesRef
    ->where('state', '>=', 'CA')
    ->where('state', '<=', 'IN');
C#
Query rangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereLessThanOrEqualTo("State", "IN");
Ruby
range_query = cities_ref.where("state", ">=", "CA").where("state", "<=", "IN")

无效:范围过滤条件针对的是不同字段

Web
citiesRef.where("state", ">=", "CA").where("population", ">", 100000)
Swift
citiesRef
    .whereField("state", isGreaterThanOrEqualTo: "CA")
    .whereField("population", isGreaterThan: 1000000)
Objective-C
[[citiesRef queryWhereField:@"state" isGreaterThanOrEqualTo:@"CA"]
    queryWhereField:@"population" isGreaterThan:@1000000];
  
Java
citiesRef.whereGreaterThanOrEqualTo("state", "CA").whereGreaterThan("population", 100000);
Kotlin
citiesRef.whereGreaterThanOrEqualTo("state", "CA")
        .whereGreaterThan("population", 100000)
Java
Query invalidRangeQuery = cities.whereGreaterThanOrEqualTo("state", "CA")
    .whereGreaterThan("population", 100000);
Python
cities_ref = db.collection(u'cities')
cities_ref.where(
    u'state', u'>=', u'CA').where(u'population', u'>=', 1000000)
Node.js
citiesRef.where('state', '>=', 'CA').where('population', '>', 1000000);
Go
query := cities.Where("state", ">=", "CA").Where("population", ">", 1000000)
PHP
$invalidRangeQuery = $citiesRef
    ->where('state', '>=', 'CA')
    ->where('population', '>', 1000000);
C#
Query invalidRangeQuery = citiesRef
    .WhereGreaterThanOrEqualTo("State", "CA")
    .WhereGreaterThan("Population", 1000000);
Ruby
invalid_range_query = cities_ref.where("state", ">=", "CA").where("population", ">", 1_000_000)

集合组范围

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合来创建 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'
    })
]);
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)
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];
  
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", "musuem");
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 Musuem");
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 Musuem 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);
Kotlin
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 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();
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'
})
Node.js
let citiesRef = db.collection('cities');

let 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'
  })
]);
Go
import (
	"context"
	"fmt"

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

// collectionGroupSetup sets up a collection group to query.
func collectionGroupSetup(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()

	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("cities")
	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
}

PHP
// Snippet not yet available
C#
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Ruby
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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(function (querySnapshot) {
    querySnapshot.forEach(function (doc) {
        console.log(doc.id, ' => ', doc.data());
    });
});
Swift
db.collectionGroup("landmarks").whereField("type", isEqualTo: "museum").getDocuments { (snapshot, error) in
    // ...
}
Objective-C
[[[self.db collectionGroupWithID:@"landmarks"] queryWhereField:@"type" isEqualTo:@"museum"]
    getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
    // ...
}];
  
Java
db.collectionGroup("landmarks").whereEqualTo("type", "museum").get()
        .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
            @Override
            public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                // ...
            }
        });
Kotlin
db.collectionGroup("landmarks").whereEqualTo("type", "museum").get()
        .addOnSuccessListener { queryDocumentSnapshots ->
            // ...
        }
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());
}
Python
museums = db.collection_group(u'landmarks')\
    .where(u'type', u'==', u'museum')
docs = museums.stream()
for doc in docs:
    print(u'{} => {}'.format(doc.id, doc.to_dict()))
Node.js
let museums = db.collectionGroup('landmarks').where('type', '==', 'museum');
museums.get().then(function(querySnapshot) {
  querySnapshot.forEach(function(doc) {
    console.log(doc.id, ' => ', doc.data());
  });
});
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
}

PHP
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C#
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Ruby
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在使用集合组查询之前,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

Cloud Firestore 不支持以下类型的查询:

  • 范围过滤条件针对的是不同字段的查询(如上一部分中所述)。
  • 逻辑 OR 查询。在这种情况下,您应该为每个 OR 条件创建一个单独的查询,并在应用中合并查询结果。
  • 使用 != 子句的查询。在这种情况下,您应该将查询拆分为一个“大于”查询和一个“小于”查询。例如,虽然查询子句 where("age", "!=", "30") 不受支持,但您可以通过将两个查询(分别使用子句 where("age", "<", "30")where("age", ">", 30))合并在一起来获得相同的结果集。