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Zamów i ogranicz dane w Cloud Firestore

Cloud Firestore zapewnia zaawansowaną funkcję zapytań do określania dokumentów, które chcesz pobrać z kolekcji. Zapytania te mogą być również używane z obu get() lub addSnapshotListener() , jak opisano w Pobierz dane .

Zamów i ogranicz dane

Domyślnie zapytanie pobiera wszystkie dokumenty, które spełniają zapytanie, w porządku rosnącym według identyfikatora dokumentu. Można określić kolejność sortowania danych przy użyciu orderBy() , można ograniczyć liczbę dokumentów pobierane za pomocą limit() .

Na przykład możesz wyszukać alfabetycznie pierwsze 3 miasta za pomocą:

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

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

PHP

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

Jedność

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

C#

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

Rubin

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

Można też sortowania w celu uzyskania ostatnich 3 miasta malejąco:

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

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

PHP

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

Jedność

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

C#

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

Rubin

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

Możesz także zamawiać według wielu pól. Na przykład, jeśli chcesz uporządkować według stanu, a w każdym stanie według populacji w porządku malejącym:

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

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

PHP

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

Jedność

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

C#

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

Rubin

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

Można łączyć where() filtry z orderBy() i limit() . W poniższym przykładzie zapytania definiują próg populacji, sortują według populacji w porządku rosnącym i zwracają tylko kilka pierwszych wyników, które przekraczają próg:

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

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

PHP

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

Jedność

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

C#

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

Rubin

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

Jednakże, jeśli masz filtr z porównania zakresu ( < , <= , > , >= ), twoja pierwsza kolejność musi być na tym samym polu, zobacz listę orderBy() ograniczenia poniżej.

Ograniczenia

Zwrócić uwagę na następujące ograniczenia dla orderBy() klauzule:

orderBy() klauzula filtruje również dla istnienia danej dziedziny. Zestaw wyników nie będzie zawierał dokumentów, które nie zawierają danych pól.

Jeśli zawierać filtr z porównania zakresu ( < , <= , > , >= ), twoja pierwsza kolejność musi być na tym samym polu:

Ważny: Przedział filtr i orderBy na tym samym polu

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

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

PHP

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

Jedność

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

C#

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

Rubin

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

Nieprawidłowy: Przedział filtr i pierwszy orderBy na różnych polach

Wersja internetowa 9

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

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

Wersja internetowa 8

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

Szybki

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

Cel C

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

Jawa

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

Kotlin+KTX

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

Jawa

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

Pyton

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

Pyton

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

Udać się

// 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');query_order_field_invalid.php

Jedność

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

C#

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

Rubin

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

Nie można zamówić zapytanie o dowolnej dziedzinie zawartych w równości ( = ) lub in klauzuli.