Cloud Firestore ile verileri sipariş edin ve sınırlayın

Cloud Firestore, bir koleksiyondan hangi belgeleri almak istediğinizi belirtmek için güçlü sorgu işlevi sağlar. Bu sorgular da ikisinden biri ile kullanılabilir get() veya addSnapshotListener() , anlatıldığı gibi Veri Al .

Verileri sipariş et ve sınırla

Varsayılan olarak bir sorgu, sorguyu karşılayan tüm belgeleri belge kimliğine göre artan sırada alır. Sen kullanarak veri için sıralama düzeni belirtebilirsiniz orderBy() ve doküman sayısı kullanılarak alınan sınırlayabilir limit() .

Örneğin, ilk 3 şehri aşağıdakilerle alfabetik olarak sorgulayabilirsiniz:

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.java

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

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

Sort son 3 şehirler almak için azalan düzende de olabilir:

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

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

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

cities_ref = db.collection(u'cities')
query = cities_ref.order_by(
    u'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

Ayrıca birden fazla alana göre sipariş verebilirsiniz. Örneğin, eyalete göre ve her eyalette nüfusa göre azalan sırayla sıralamak istiyorsanız:

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", Direction.DESCENDING);
DocSnippets.java

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

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

cities_ref = db.collection(u'cities')
cities_ref.order_by(u'state').order_by(
    u'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

Birleştirebilirsiniz where() ile filtreler orderBy() ve limit() . Aşağıdaki örnekte, sorgular bir popülasyon eşiği tanımlar, popülasyona göre artan düzende sıralar ve yalnızca eşiği aşan ilk birkaç sonucu döndürür:

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.java

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

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

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

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

Ancak bir dizi karşılaştırma ile bir filtre varsa, ( < , <= , > , >= ), ilk sipariş, aynı alanda olmalıdır listesine bakın orderBy() aşağıda sınırlamaları.

sınırlamalar

Aşağıdaki kısıtlamalara dikkat orderBy() maddeleri:

• Bir orderBy() hükmü de verilen alanların varlığı için filtreler. Sonuç kümesi, verilen alanları içermeyen belgeleri içermeyecektir.

• Bir aralık karşılaştırma ile bir filtre eklerseniz ( < , <= , > , >= ), ilk sipariş aynı alanda olmalıdır:

  Geçerli: Menzil filtresi ve orderBy aynı sahada

  Web sürümü 9

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

  Web sürümü 8

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

  Süratli

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

  Amaç-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

  piton

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

  piton

  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

  Gitmek

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

  PHP

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

  Birlik

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

  C#

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

  yakut

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

  Geçersiz: Menzil filtresi ve ilk orderBy farklı alanlarda

  Web sürümü 9

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

  Web sürümü 8

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

  Süratli

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

  Amaç-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

  piton

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

  piton

  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

  Gitmek

  // 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

  Birlik

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

  C#

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

  yakut

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

• Herhangi bir eşitlik dahil alan (da sorgunuzu sipariş edemez = ) ya da in maddesi.