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Pesan dan batasi data dengan Cloud Firestore

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

Memesan dan membatasi data

Secara default, kueri mengambil semua dokumen yang memenuhi kueri dalam urutan menaik menurut ID dokumen. Anda dapat menentukan tata urutan untuk data Anda menggunakan orderBy() , dan Anda dapat membatasi jumlah dokumen yang diambil menggunakan limit() .

Misalnya, Anda dapat meminta 3 kota pertama menurut abjad dengan:

Web version 9

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

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

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Kotlin+KTX

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

Java

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

Dart

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

Jawa

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

Piton

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

Python

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

C++

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

Node.js

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

Pergi

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

PHP

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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

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

Web version 9

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

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

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Kotlin+KTX

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

Java

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

Dart

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

Jawa

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

Piton

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

Python

cities_ref = db.collection("cities")
query = cities_ref.order_by("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

Pergi

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

PHP

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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

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

Web version 9

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

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

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Kotlin+KTX

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

Java

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

Dart

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

Jawa

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

Piton

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

Python

cities_ref = db.collection("cities")
cities_ref.order_by("state").order_by(
    "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

Pergi

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

PHP

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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

Anda dapat menggabungkan filter where where() dengan orderBy() dan limit() . Dalam contoh berikut, kueri menentukan ambang populasi, mengurutkan berdasarkan populasi dalam urutan menaik, dan mengembalikan hanya beberapa hasil pertama yang melebihi ambang:

Web version 9

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

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

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Kotlin+KTX

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

Java

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

Dart

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

Jawa

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

Piton

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

Python

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

Pergi

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

PHP

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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 Anda harus berada di kolom yang sama, lihat daftar batasan orderBy() di bawah.

Keterbatasan

Perhatikan batasan berikut untuk klausa orderBy() :

orderBy() juga memfilter keberadaan bidang yang diberikan. Kumpulan hasil tidak akan menyertakan dokumen yang tidak berisi bidang yang diberikan.

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

Valid : Range filter dan orderBy pada kolom yang sama

Web version 9

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

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

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

[[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

Jawa

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

Piton

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

Python

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

Node.js

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

Pergi

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

PHP

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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

Tidak valid : Filter rentang dan pesanan pertama orderBy pada bidang yang berbeda

Web version 9

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

const q = query(citiesRef, where("population", ">", 100000), orderBy("country"));invalid_filter_and_order.js

Web version 8

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

Cepat

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

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

Objective-C

Catatan: Produk ini tidak tersedia di watchOS dan target Cuplikan Aplikasi.

[[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

Jawa

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

Piton

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

Python

cities_ref = db.collection("cities")
query = cities_ref.where("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

Pergi

// 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

Untuk mengetahui selengkapnya tentang menginstal dan membuat klien Cloud Firestore, lihat Perpustakaan Klien Cloud Firestore .

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

Persatuan

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

C#

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

Rubi

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

Anda tidak dapat mengurutkan kueri berdasarkan bidang apa pun yang disertakan dalam kesetaraan ( = ) atau in klausa.