Firestore - Order and limit data

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 query() or addSnapshotListener(), as described in Get Data.

Order and limit data

You can specify the sort order for your data using orderBy(), and you can limit the number of documents retrieved using limit().

For example, you could query for the first 3 cities alphabetically with:

var query:Query = citiesRef
                    .orderBy( "name" )
                    .limit( 3 );

You could also sort in descending order to get the last 3 cities:

var query:Query = citiesRef
                    .orderBy( "name", QueryDirection.DESCENDING )
                    .limit( 3 );

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:

var query:Query = citiesRef
                    .orderBy( "state" )
                    .orderBy( "population", QueryDirection.DESCENDING );

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:

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

However, if you have a filter with a range comparison (<, <=, >, >=), your first ordering must be on the same field:

Valid: Range filter and orderBy on the same field

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

Invalid: Range filter and first orderBy on different fields

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

Default order

By default, a query retrieves all documents that satisfy the query in ascending order by document ID.

You can alter this by using the predefined field path value: FieldPath.documentId() and passing it to the orderBy() method. For example:

var query:Query = citiesRef
                    .orderBy( FieldPath.documentId(), QueryDirection.DESCENDING );