Mengurutkan dan membatasi data dengan Cloud Firestore

Cloud Firestore menyediakan fungsionalitas kueri yang dapat diandalkan untuk menentukan dokumen mana yang ingin Anda ambil dari koleksi. Kueri ini juga dapat digunakan dengan get() atau addSnapshotListener(), seperti yang dijelaskan dalam artikel Mendapatkan Data.

Mengurutkan dan membatasi data

Secara default, suatu kueri akan mengambil semua dokumen yang memenuhi kueri tersebut dalam urutan menaik menurut ID dokumen. Anda dapat menentukan tata urutan data untuk menggunakan orderBy(), dan membatasi jumlah dokumen yang diambil menggunakan limit(). Jika Anda menentukan limit(), nilai harus lebih besar dari atau sama dengan nol.

Misalnya, Anda dapat mengajukan kueri untuk 3 kota pertama menurut abjad dengan:

import { query, orderBy, limit } from "firebase/firestore";  

const q = query(citiesRef, orderBy("name"), limit(3));
order_and_limit.js

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

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

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

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

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

final citiesRef = db.collection("cities");
citiesRef.orderBy("name").limit(3);
firestore.dart

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

cities_ref = db.collection("cities")
query = cities_ref.order_by("name").limit_to_last(2)
results = query.get()
snippets.py

cities_ref = db.collection("cities")
query = cities_ref.order_by("name").limit_to_last(2)
results = await query.get()
snippets.py

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

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

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

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

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

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

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

Anda juga dapat mengurutkan dalam urutan menurun untuk mendapatkan 3 kota terakhir:

import { query, orderBy, limit } from "firebase/firestore";  

const q = query(citiesRef, orderBy("name", "desc"), limit(3));
order_and_limit_desc.js

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

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

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

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

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

final citiesRef = db.collection("cities");
citiesRef.orderBy("name", descending: true).limit(3);
firestore.dart

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

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

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

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

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

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

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

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

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

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

Anda juga dapat mengurutkan berdasarkan beberapa kolom. Misalnya, jika Anda ingin mengurutkan berdasarkan negara bagian, dan dalam setiap negara bagian mengurutkan berdasarkan populasi dalam urutan menurun:

import { query, orderBy } from "firebase/firestore";  

const q = query(citiesRef, orderBy("state"), orderBy("population", "desc"));
order_multiple.js

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

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

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

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

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

final citiesRef = db.collection("cities");
citiesRef.orderBy("state").orderBy("population", descending: true);
firestore.dart

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

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

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

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

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

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

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

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

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

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

Anda dapat menggabungkan filter where() dengan orderBy() dan limit(). Dalam contoh berikut, kueri menentukan nilai minimum populasi, mengurutkan berdasarkan populasi secara menaik, dan hanya mengembalikan beberapa hasil pertama yang melampaui nilai minimum tersebut:

import { query, where, orderBy, limit } from "firebase/firestore";  

const q = query(citiesRef, where("population", ">", 100000), orderBy("population"), limit(2));
filter_and_order.js

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

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

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

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

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

final citiesRef = db.collection("cities");
citiesRef
    .where("population", isGreaterThan: 100000)
    .orderBy("population")
    .limit(2);
firestore.dart

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

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

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

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

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

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

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

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

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

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

Namun, jika Anda memiliki filter dengan perbandingan rentang (<, <=, >, >=), pengurutan pertama harus berada di kolom yang sama. Lihat daftar batasan orderBy() di bawah ini.

Batasan

Perhatikan batasan berikut untuk klausa orderBy():

• Klausa orderBy() juga memfilter ada tidaknya kolom yang dimaksud. Kumpulan hasilnya tidak akan menyertakan dokumen yang tidak berisi kolom yang dimaksud.

• Jika Anda menyertakan filter dengan perbandingan rentang (<, <=, >, >=), pengurutan pertama harus berada di kolom yang sama:

  Valid: Filter rentang dan orderBy berada di kolom yang sama

  API modular web

  import { query, where, orderBy } from "firebase/firestore";  
  
  const q = query(citiesRef, where("population", ">", 100000), orderBy("population"));
  valid_filter_and_order.js

  API dengan namespace web

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

  Swift

  Catatan: Produk ini tidak tersedia di target watchOS dan App Clip.

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

  Objective-C

  Catatan: Produk ini tidak tersedia di target watchOS dan App Clip.

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

  Kotlin+KTX

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

  Java

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

  Dart

  final citiesRef = db.collection("cities");
  citiesRef.where("population", isGreaterThan: 100000).orderBy("population");
  firestore.dart

  Java

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

  Python

  cities_ref = db.collection("cities")
  query = cities_ref.where(filter=FieldFilter("population", ">", 2500000)).order_by(
      "population"
  )
  results = query.stream()
  snippets.py

  Python

  cities_ref = db.collection("cities")
  query = cities_ref.where(filter=FieldFilter("population", ">", 2500000)).order_by(
      "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

  PHP

  Untuk mengetahui informasi lebih lanjut tentang cara menginstal dan membuat klien Cloud Firestore, lihat Library Klien Cloud Firestore.

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

  Tidak valid: Filter rentang dan orderBy pertama berada di kolom berbeda

  API modular web

  import { query, where, orderBy } from "firebase/firestore";  
  
  const q = query(citiesRef, where("population", ">", 100000), orderBy("country"));
  invalid_filter_and_order.js

  API dengan namespace web

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

  Swift

  Catatan: Produk ini tidak tersedia di target watchOS dan App Clip.

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

  Objective-C

  Catatan: Produk ini tidak tersedia di target watchOS dan App Clip.

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

  Kotlin+KTX

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

  Java

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

  Dart

  final citiesRef = db.collection("cities");
  citiesRef.where("population", isGreaterThan: 100000).orderBy("country");
  firestore.dart

  Java

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

  Python

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

  Python

  cities_ref = db.collection("cities")
  query = cities_ref.where(filter=FieldFilter("population", ">", 2500000)).order_by(
      "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

  PHP

  Untuk mengetahui informasi lebih lanjut tentang cara menginstal dan membuat klien Cloud Firestore, lihat Library Klien Cloud Firestore.

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

orderBy dan keberadaannya

Saat Anda mengurutkan kueri berdasarkan kolom tertentu, kueri tersebut hanya dapat menampilkan dokumen yang memiliki urutan berdasarkan kolom.

Misalnya, kueri berikut tidak akan menampilkan dokumen apa pun yang tidak memiliki kolom population, meskipun kolom tersebut memenuhi filter kueri.

db.collection("cities").whereEqualTo("country", “USA”).orderBy(“population”);

Efek terkait berlaku pada ketidaksetaraan. Kueri dengan filter ketidaksetaraan pada satu kolom juga menyiratkan pengurutan berdasarkan kolom tersebut. Kueri berikut tidak menampilkan dokumen tanpa kolom population sekalipun country = USA dalam dokumen tersebut . Sebagai solusinya, Anda dapat menjalankan kueri terpisah untuk setiap pengurutan atau menetapkan nilai untuk semua kolom yang Anda urutkan.

db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000));

Kueri di atas mencakup urutan tersirat berdasarkan ketidaksetaraan dan setara dengan hal berikut:

db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000)).orderBy(“population”);