Firestore - Paginate data with query cursors

With query cursors in Cloud Firestore, you can split data returned by a query into batches according to the parameters you define in your query.

Query cursors define the start and end points for a query, allowing you to:

• Return a subset of the data.
• Paginate query results.

However, to define a specific range for a query, you should use the where() method described in Simple Queries.

Add a simple cursor to a query

Use the startAt() or startAfter() methods to define the start point for a query. The startAt() method includes the start point, while the startAfter() method excludes it.

For example, if you use startAt(A) in a query, it returns the entire alphabet. If you use startAfter(A) instead, it returns B-Z.

// Get all cities with a population >= 1,000,000, ordered by population,
db.collection("cities")
        .orderBy("population")
        .startAt(1000000);

Similarly, use the endAt() or endBefore() methods to define an end point for your query results.

// Get all cities with a population <= 1,000,000, ordered by population,
db.collection("cities")
        .orderBy("population")
        .endAt(1000000);

Paginate a query

NOT YET AVAILABLE Coming soon

Paginate queries by combining query cursors with the limit() method. For example, use the last document in a batch as the start of a cursor for the next batch.

var first:Query = FirebaseFirestore.service.collection("users")
        .orderBy("born")
        .limit(5);

first.query()
        .addOnQuerySuccessHandler( function( snapshot:QuerySnapshot ):void
        {
            // Get the last visible document
            var lastVisible:DocumentSnapshot = snapshot.getDocuments()[ snapshot.size - 1 ];
            
            var next:Query = FirebaseFirestore.service.collection("users")
                    .orderBy("born")
                    .startAtSnapshot(lastVisible)
                    .limit(5);
            
            // Use the query for pagination
            // ...
        });

Set multiple cursor conditions

To add more granularity to your cursor's start or end point, you can specify multiple conditions in the cursor clause. This is particularly useful if your data set includes fields where the first condition in a cursor clause would return multiple results. Use multiple conditions to further specify the start or end point and reduce ambiguity.

For example, in a data set containing all the cities named "Springfield" in the United States, there would be multiple start points for a query set to start at "Springfield":

Cities
Name	State
Springfield	Massachusetts
Springfield	Missouri
Springfield	Wisconsin

To start at a specific Springfield, you could add the state as a secondary condition in your cursor clause.

// Will return all Springfields
FirebaseFirestore.service.collection("cities")
        .orderBy("name")
        .orderBy("state")
        .startAt("Springfield");

// Will return "Springfield, Missouri" and "Springfield, Wisconsin"
FirebaseFirestore.service.collection("cities")
        .orderBy("name")
        .orderBy("state")
        .startAt("Springfield", "Missouri");