Cloud Firestore provides powerful query functionality for specifying which
documents you want to retrieve from a collection. These queries can also be used
with either get() or addSnapshotListener(), as described in Get
Data.
Order and limit data
By default, a query retrieves all documents that satisfy the query in ascending
order by document ID. You can specify the sort order for your data using
orderBy(), and you can limit the number of documents retrieved using
limit(). If you specify a limit(), the value must be greater than or equal
to zero.
For example, you could query for the first 3 cities alphabetically with:
Web
import { query, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, orderBy("name"), limit(3));
Web
citiesRef.orderBy("name").limit(3);
Swift
citiesRef.order(by: "name").limit(to: 3)
Objective-C
[[citiesRef queryOrderedByField:@"name"] queryLimitedTo:3];
Kotlin
citiesRef.orderBy("name").limit(3)
Java
citiesRef.orderBy("name").limit(3);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("name").limit(3);
Java
Python
Python
C++
cities_ref.OrderBy("name").Limit(3);
Node.js
Go
PHP
PHP
For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.
Unity
Query query = citiesRef.OrderBy("Name").Limit(3);
C#
Ruby
You could also sort in descending order to get the last 3 cities:
Web
import { query, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, orderBy("name", "desc"), limit(3));
Web
citiesRef.orderBy("name", "desc").limit(3);
Swift
citiesRef.order(by: "name", descending: true).limit(to: 3)
Objective-C
[[citiesRef queryOrderedByField:@"name" descending:YES] queryLimitedTo:3];
Kotlin
citiesRef.orderBy("name", Query.Direction.DESCENDING).limit(3)
Java
citiesRef.orderBy("name", Direction.DESCENDING).limit(3);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("name", descending: true).limit(3);
Java
Python
Python
C++
cities_ref.OrderBy("name", Query::Direction::kDescending).Limit(3);
Node.js
Go
PHP
PHP
For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.
Unity
Query query = citiesRef.OrderByDescending("Name").Limit(3);
C#
Ruby
You can also order by multiple fields. For example, if you wanted to order by state, and within each state order by population in descending order:
Web
import { query, orderBy } from "firebase/firestore"; const q = query(citiesRef, orderBy("state"), orderBy("population", "desc"));
Web
citiesRef.orderBy("state").orderBy("population", "desc");
Swift
citiesRef .order(by: "state") .order(by: "population", descending: true)
Objective-C
[[citiesRef queryOrderedByField:@"state"] queryOrderedByField:@"population" descending:YES];
Kotlin
citiesRef.orderBy("state").orderBy("population", Query.Direction.DESCENDING)
Java
citiesRef.orderBy("state").orderBy("population", Direction.DESCENDING);
Dart
final citiesRef = db.collection("cities"); citiesRef.orderBy("state").orderBy("population", descending: true);
Java
Python
Python
C++
cities_ref.OrderBy("state").OrderBy("name", Query::Direction::kDescending);
Node.js
Go
PHP
PHP
For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.
Unity
Query query = citiesRef.OrderBy("State").OrderByDescending("Population");
C#
Ruby
You can combine where() filters with orderBy() and limit(). In the
following example, the queries define a population threshold, sort by population
in ascending order, and return only the first few results that exceed the
threshold:
Web
import { query, where, orderBy, limit } from "firebase/firestore"; const q = query(citiesRef, where("population", ">", 100000), orderBy("population"), limit(2));
Web
citiesRef.where("population", ">", 100000).orderBy("population").limit(2);
Swift
citiesRef .whereField("population", isGreaterThan: 100000) .order(by: "population") .limit(to: 2)
Objective-C
[[[citiesRef queryWhereField:@"population" isGreaterThan:@100000] queryOrderedByField:@"population"] queryLimitedTo:2];
Kotlin
citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2)
Java
citiesRef.whereGreaterThan("population", 100000).orderBy("population").limit(2);
Dart
final citiesRef = db.collection("cities"); citiesRef .where("population", isGreaterThan: 100000) .orderBy("population") .limit(2);
Java
Python
Python
C++
cities_ref.WhereGreaterThan("population", FieldValue::Integer(100000)) .OrderBy("population") .Limit(2);
Node.js
Go
PHP
PHP
For more on installing and creating a Cloud Firestore client, refer to Cloud Firestore Client Libraries.
Unity
Query query = citiesRef .WhereGreaterThan("Population", 2500000) .OrderBy("Population") .Limit(2);
C#
Ruby
However, if you have a filter with a range comparison (<, <=, >, >=),
your first ordering must be on the same field, see the list of orderBy()
limitations below.
Limitations
Note the following restriction for orderBy() clauses:
- An
orderBy()clause also filters for existence of the given fields. The result set will not include documents that do not contain the given fields.
orderBy and existence
When you order a query by a given field, the query can return only the documents where the order-by field exists.
For example, the following query would not return any documents where the
population field is not set, even if they otherwise meet the query filters.
Java
db.collection("cities").whereEqualTo("country", “USA”).orderBy(“population”);
A related effect applies to inequalities. A query with an inequality filter
on a field also implies ordering by that field. The following
query does not return documents without a population field even
if country = USA in that document . As a workaround, you can execute
separate queries for each ordering or you can assign a value for all fields
that you order by.
Java
db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000));
The query above includes an implied order-by on the inequality and is equivalent to the following:
Java
db.collection(“cities”).where(or(“country”, USA”), greaterThan(“population”, 250000)).orderBy(“population”);