Ordena y limita datos

Firestore proporciona una potente función de consulta para especificar qué documentos deseas recuperar de una colección. Estas consultas también se pueden usar con get() o addSnapshotListener(), como se describe en Obtén datos.

Ordena y limita los datos

Según la configuración predeterminada, una consulta recupera todos los documentos que corresponden con la consulta en orden ascendente por ID de documento. Puedes especificar el orden de clasificación para los datos que usan orderBy() y, con limit(), puedes limitar la cantidad de documentos recuperados.

Por ejemplo, puedes realizar una consulta que te muestre las primeras 3 ciudades en orden alfabético con:

Web

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
Android

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

Kotlin+KTX
Android

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

También puedes ordenar de forma descendente para ver las últimas 3 ciudades:

Web

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
Android

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

Kotlin+KTX
Android

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

También puedes ordenar según varios campos. Por ejemplo, si deseas ordenar por estado y, dentro de cada estado, por población de manera descendente:

Web

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
Android

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

Kotlin+KTX
Android

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

Puedes combinar filtros where() con orderBy() y limit(). En el ejemplo siguiente, las consultas definen un umbral de población, clasifican por población en orden ascendente y muestran solo los primeros resultados que superan el umbral:

Web

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
Android

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

Kotlin+KTX
Android

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

Sin embargo, si tienes un filtro con una comparación de rangos (<, <=, > y >=), el primer ordenamiento debe estar en el mismo campo, consulta la lista de limitaciones de orderBy() a continuación.

Limitaciones

Ten en cuenta las siguientes restricciones para las cláusulas orderBy():

Una cláusula orderBy() también filtra en busca de los campos especificados. El conjunto de resultados no incluirá documentos que no contengan los campos correspondientes.

Si incluyes un filtro con una comparación de rangos (<, <=, > y >=), el primer ordenamiento debe estar en el mismo campo:

Válido: Filtro de rango y orderBy en el mismo campo

Web

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
Android

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

Kotlin+KTX
Android

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

No válido: Filtro de rango y primer orderBy en campos distintos

Web

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
Android

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

Kotlin+KTX
Android

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

$query = $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

No puedes ordenar la consulta según ningún campo incluido en una cláusula de igualdad (=) o in.

Ordena y limita datos

Ordena y limita los datos

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