Cloud Firestore でのデータの並べ替えと制限

Cloud Firestore には、コレクションから取得するドキュメントを指定できる強力なクエリ機能があります。これらのクエリは、データを取得するで説明しているように、get() または addSnapshotListener() とあわせて使用することもできます。

データの並べ替えと制限

デフォルトでは、クエリを満たすすべてのドキュメントが、ドキュメント ID の昇順で取得されます。orderBy() を使用してデータの並べ替え順を指定したり、limit() を使用して取得するドキュメントの数を制限したりできます。

たとえば、英字順に並べ替え、最初の 3 つの都市を取得するには、次のようにします。

ウェブ

citiesRef.orderBy("name").limit(3);test.firestore.js

Swift

citiesRef.order(by: "name").limit(to: 3)ViewController.swift

Objective-C

[[citiesRef queryOrderedByField:@"name"] queryLimitedTo:3];ViewController.m

Java

citiesRef.orderBy("name").limit(3);DocSnippets.java

Kotlin+KTX

citiesRef.orderBy("name").limit(3)DocSnippets.kt

Java

Query query = cities.orderBy("name").limit(3);
Query query = cities.orderBy("name").limitToLast(3);QueryDataSnippets.java

Python

db.collection(u'cities').order_by(u'name').limit(3).stream()snippets.py

C++

cities_ref.OrderBy("name").Limit(3);snippets.cpp

Node.js

const firstThreeRes = await citiesRef.orderBy('name').limit(3).get();index.js

Go

query := cities.OrderBy("name", firestore.Asc).Limit(3)query.go

PHP

$query = $citiesRef->orderBy('name')->limit(3);order_by_name_limit_query.php

Unity

Query query = citiesRef.OrderBy("Name").Limit(3);

C#

Query query = citiesRef.OrderBy("Name").Limit(3);Program.cs

Ruby

query = cities_ref.order("name").limit(3)order_limit_data.rb

また、降順で並べ替え、最後の 3 つの都市を取得することもできます。

ウェブ

citiesRef.orderBy("name", "desc").limit(3);test.firestore.js

Swift

citiesRef.order(by: "name", descending: true).limit(to: 3)ViewController.swift

Objective-C

[[citiesRef queryOrderedByField:@"name" descending:YES] queryLimitedTo:3];ViewController.m

Java

citiesRef.orderBy("name", Direction.DESCENDING).limit(3);DocSnippets.java

Kotlin+KTX

citiesRef.orderBy("name", Query.Direction.DESCENDING).limit(3)DocSnippets.kt

Java

Query query = cities.orderBy("name", Direction.DESCENDING).limit(3);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
query = cities_ref.order_by(
    u'name', direction=firestore.Query.DESCENDING).limit(3)
results = query.stream()snippets.py

C++

cities_ref.OrderBy("name", Query::Direction::kDescending).Limit(3);snippets.cpp

Node.js

const lastThreeRes = await citiesRef.orderBy('name', 'desc').limit(3).get();index.js

Go

query := cities.OrderBy("name", firestore.Desc).Limit(3)query.go

PHP

$query = $citiesRef->orderBy('name', 'DESC')->limit(3);order_by_name_desc_limit_query.php

Unity

Query query = citiesRef.OrderByDescending("Name").Limit(3);

C#

Query query = citiesRef.OrderByDescending("Name").Limit(3);Program.cs

Ruby

query = cities_ref.order("name", "desc").limit(3)order_limit_data.rb

複数のフィールドで並べ替えを行うこともできます。たとえば、州で並べ替え、各州の中で人口の降順で並べ替える場合は、次のようにします。

ウェブ

citiesRef.orderBy("state").orderBy("population", "desc");test.firestore.js

Swift

citiesRef
    .order(by: "state")
    .order(by: "population", descending: true)ViewController.swift

Objective-C

[[citiesRef queryOrderedByField:@"state"] queryOrderedByField:@"population" descending:YES];ViewController.m

Java

citiesRef.orderBy("state").orderBy("population", Direction.DESCENDING);DocSnippets.java

Kotlin+KTX

citiesRef.orderBy("state").orderBy("population", Query.Direction.DESCENDING)DocSnippets.kt

Java

Query query = cities.orderBy("state").orderBy("population", Direction.DESCENDING);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
cities_ref.order_by(u'state').order_by(
    u'population', direction=firestore.Query.DESCENDING)snippets.py

C++

cities_ref.OrderBy("state").OrderBy("name", Query::Direction::kDescending);snippets.cpp

Node.js

const byStateByPopRes = await citiesRef.orderBy('state').orderBy('population', 'desc').get();index.js

Go

query := client.Collection("cities").OrderBy("state", firestore.Asc).OrderBy("population", firestore.Desc)query.go

PHP

$query = $citiesRef->orderBy('state')->orderBy('population', 'DESC');order_by_state_and_population_query.php

Unity

Query query = citiesRef.OrderBy("State").OrderByDescending("Population");

C#

Query query = citiesRef.OrderBy("State").OrderByDescending("Population");Program.cs

Ruby

query = cities_ref.order("state").order("population", "desc")order_limit_data.rb

where() フィルタは orderBy() や limit() と組み合わせることが可能です。次の例では、クエリによって人口のしきい値が定義され、人口の昇順で並べ替えて、しきい値を超えている最初の数件の結果のみが返されます。

ウェブ

citiesRef.where("population", ">", 100000).orderBy("population").limit(2);test.firestore.js

Swift

citiesRef
    .whereField("population", isGreaterThan: 100000)
    .order(by: "population")
    .limit(to: 2)ViewController.swift

Objective-C

[[[citiesRef queryWhereField:@"population" isGreaterThan:@100000]
    queryOrderedByField:@"population"]
    queryLimitedTo:2];ViewController.m

Java

citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2);DocSnippets.java

Kotlin+KTX

citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2)DocSnippets.kt

Java

Query query = cities.whereGreaterThan("population", 2500000L).orderBy("population").limit(2);QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
query = cities_ref.where(
    u'population', u'>', 2500000).order_by(u'population').limit(2)
results = query.stream()snippets.py

C++

cities_ref.WhereGreaterThan("population", FieldValue::Integer(100000))
    .OrderBy("population")
    .Limit(2);snippets.cpp

Node.js

const biggestRes = await citiesRef.where('population', '>', 2500000)
  .orderBy('population').limit(2).get();index.js

Go

query := cities.Where("population", ">", 2500000).OrderBy("population", firestore.Desc).Limit(2)query.go

PHP

$query = $citiesRef
    ->where('population', '>', 2500000)
    ->orderBy('population')
    ->limit(2);where_order_by_limit_query.php

Unity

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Population")
    .Limit(2);

C#

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Population")
    .Limit(2);Program.cs

Ruby

query = cities_ref.where("population", ">", 2_500_000).order("population").limit(2)order_limit_data.rb

ただし、範囲比較（<、<=、>、>=）のフィルタがある場合、最初の並べ替えは同じフィールドで行う必要があります。下の orderBy() の制限事項の一覧をご覧ください。

制限事項

orderBy() 句の次の制限事項に注意してください。

orderBy() 句は、指定したフィールドの有無によるフィルタも行います。指定したフィールドがないドキュメントは結果セットには含まれません。

範囲比較（<、<=、>、>=）のフィルタを含める場合、最初の並べ替えは同じフィールドで行う必要があります。

有効: 範囲フィルタと orderBy を同じフィールドに使用する

ウェブ

citiesRef.where("population", ">", 100000).orderBy("population");test.firestore.js

Swift

citiesRef
    .whereField("population", isGreaterThan: 100000)
    .order(by: "population")ViewController.swift

Objective-C

[[citiesRef queryWhereField:@"population" isGreaterThan:@100000]
    queryOrderedByField:@"population"];ViewController.m

Java

citiesRef.whereGreaterThan("population", 100000).orderBy("population");DocSnippets.java

Kotlin+KTX

citiesRef.whereGreaterThan("population", 100000).orderBy("population")DocSnippets.kt

Java

Query query = cities.whereGreaterThan("population", 2500000L).orderBy("population");QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
query = cities_ref.where(
    u'population', u'>', 2500000).order_by(u'population')
results = query.stream()snippets.py

Node.js

citiesRef.where('population', '>', 2500000).orderBy('population');index.js

Go

query := cities.Where("population", ">", 2500000).OrderBy("population", firestore.Asc)query.go

PHP

$query = $citiesRef
    ->where('population', '>', 2500000)
    ->orderBy('population');range_order_by_query.php

Unity

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Population");

C#

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Population");Program.cs

Ruby

query = cities_ref.where("population", ">", 2_500_000).order("population")order_limit_data.rb

無効: 範囲フィルタと最初の orderBy を異なるフィールドに使用する

ウェブ

citiesRef.where("population", ">", 100000).orderBy("country");test.firestore.js

Swift

citiesRef
    .whereField("population", isGreaterThan: 100000)
    .order(by: "country")ViewController.swift

Objective-C

[[citiesRef queryWhereField:@"population" isGreaterThan:@100000] queryOrderedByField:@"country"];ViewController.m

Java

citiesRef.whereGreaterThan("population", 100000).orderBy("country");DocSnippets.java

Kotlin+KTX

citiesRef.whereGreaterThan("population", 100000).orderBy("country")DocSnippets.kt

Java

Query query = cities.whereGreaterThan("population", 2500000L).orderBy("country");QueryDataSnippets.java

Python

cities_ref = db.collection(u'cities')
query = cities_ref.where(u'population', u'>', 2500000).order_by(u'country')
results = query.stream()snippets.py

C++

// BAD EXAMPLE -- will crash the program:
cities_ref.WhereGreaterThan("population", FieldValue::Integer(100000))
    .OrderBy("country");snippets.cpp

Node.js

citiesRef.where('population', '>', 2500000).orderBy('country');index.js

Go

// Note: This is an invalid query. It violates the constraint that range
// and order by are required to be on the same field.
query := cities.Where("population", ">", 2500000).OrderBy("country", firestore.Asc)query.go

PHP

$invalidRangeQuery = $citiesRef
    ->where('population', '>', 2500000)
    ->orderBy('country');invalid_range_order_by_query.php

Unity

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Country");

C#

Query query = citiesRef
    .WhereGreaterThan("Population", 2500000)
    .OrderBy("Country");Program.cs

Ruby

query = cities_ref.where("population", ">", 2_500_000).order("country")order_limit_data.rb

等価（=）または in 句に含まれるフィールドでクエリを並べ替えることはできません。