CollectionReference

public class CollectionReference extends Query

java.lang.Object
↳	com.google.firebase.firestore.Query
	↳	com.google.firebase.firestore.CollectionReference

A CollectionReference can be used for adding documents, getting document references, and querying for documents (using the methods inherited from Query).

Subclassing Note: Cloud Firestore classes are not meant to be subclassed except for use in test mocks. Subclassing is not supported in production code and new SDK releases may break code that does so.

Summary

Public methods
`@NonNull Task<DocumentReference>`	`add(@NonNull Object data)` Adds a new document to this collection with the specified data, assigning it a document ID automatically.
`@NonNull DocumentReference`	`document()` Returns a `DocumentReference` pointing to a new document with an auto-generated ID within this collection.
`@NonNull DocumentReference`	`document(@NonNull String documentPath)` Gets a `DocumentReference` instance that refers to the document at the specified path within this collection.
`@NonNull String`	`getId()`
`@Nullable DocumentReference`	`getParent()` Gets a `DocumentReference` to the document that contains this collection.
`@NonNull String`	`getPath()` Gets the path of this collection (relative to the root of the database) as a slash-separated string.

Inherited fields

From com.google.firebase.firestore.Query

final FirebaseFirestore

firestore

Inherited methods

From com.google.firebase.firestore.Query

`@NonNull ListenerRegistration`	`addSnapshotListener(@NonNull EventListener<QuerySnapshot> listener)` Starts listening to this query.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull Activity activity, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query using an Activity-scoped listener.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull Executor executor, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull MetadataChanges metadataChanges, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query with the given options.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull SnapshotListenOptions options, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query with the given options.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull Activity activity, @NonNull MetadataChanges metadataChanges, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query with the given options, using an Activity-scoped listener.
`@NonNull ListenerRegistration`	`addSnapshotListener( @NonNull Executor executor, @NonNull MetadataChanges metadataChanges, @NonNull EventListener<QuerySnapshot> listener )` Starts listening to this query with the given options.
`@NonNull AggregateQuery`	`aggregate( @NonNull AggregateField aggregateField, @NonNull AggregateField[] aggregateFields )` Calculates the specified aggregations over the documents in the result set of the given query without actually downloading the documents.
`@NonNull AggregateQuery`	`count()` Returns a query that counts the documents in the result set of this query.
`@NonNull Query`	`endAt(Object[] fieldValues)` Creates and returns a new `Query` that ends at the provided fields relative to the order of the query.
`@NonNull Query`	`endAt(@NonNull DocumentSnapshot snapshot)` Creates and returns a new `Query` that ends at the provided document (inclusive).
`@NonNull Query`	`endBefore(Object[] fieldValues)` Creates and returns a new `Query` that ends before the provided fields relative to the order of the query.
`@NonNull Query`	`endBefore(@NonNull DocumentSnapshot snapshot)` Creates and returns a new `Query` that ends before the provided document (exclusive).
`boolean`	`equals(Object o)`
`@NonNull Task<QuerySnapshot>`	`get()` Executes the query and returns the results as a `QuerySnapshot`.
`@NonNull Task<QuerySnapshot>`	`get(@NonNull Source source)` Executes the query and returns the results as a `QuerySnapshot`.
`@NonNull FirebaseFirestore`	`getFirestore()` Gets the Cloud Firestore instance associated with this query.
`int`	`hashCode()`
`@NonNull Query`	`limit(long limit)` Creates and returns a new `Query` that only returns the first matching documents up to the specified number.
`@NonNull Query`	`limitToLast(long limit)` Creates and returns a new `Query` that only returns the last matching documents up to the specified number.
`@NonNull Query`	`orderBy(@NonNull String field)` Creates and returns a new `Query` that's additionally sorted by the specified field.
`@NonNull Query`	`orderBy(@NonNull FieldPath fieldPath)` Creates and returns a new `Query` that's additionally sorted by the specified field.
`@NonNull Query`	`orderBy(@NonNull String field, @NonNull Query.Direction direction)` Creates and returns a new `Query` that's additionally sorted by the specified field, optionally in descending order instead of ascending.
`@NonNull Query`	`orderBy(@NonNull FieldPath fieldPath, @NonNull Query.Direction direction)` Creates and returns a new `Query` that's additionally sorted by the specified field, optionally in descending order instead of ascending.
`@NonNull Query`	`startAfter(Object[] fieldValues)` Creates and returns a new `Query` that starts after the provided fields relative to the order of the query.
`@NonNull Query`	`startAfter(@NonNull DocumentSnapshot snapshot)` Creates and returns a new `Query` that starts after the provided document (exclusive).
`@NonNull Query`	`startAt(Object[] fieldValues)` Creates and returns a new `Query` that starts at the provided fields relative to the order of the query.
`@NonNull Query`	`startAt(@NonNull DocumentSnapshot snapshot)` Creates and returns a new `Query` that starts at the provided document (inclusive).
`@NonNull Query`	`where(@NonNull Filter filter)` Creates and returns a new `Query` with the additional filter.
`@NonNull Query`	`whereArrayContains(@NonNull String field, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field, the value must be an array, and that the array must contain the provided value.
`@NonNull Query`	`whereArrayContains(@NonNull FieldPath fieldPath, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field, the value must be an array, and that the array must contain the provided value.
`@NonNull Query`	`whereArrayContainsAny(@NonNull String field, @NonNull List<Object> values)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field, the value must be an array, and that the array must contain at least one value from the provided list.
`@NonNull Query`	`whereArrayContainsAny( @NonNull FieldPath fieldPath, @NonNull List<Object> values )` Creates and returns a new `Query` with the additional filter that documents must contain the specified field, the value must be an array, and that the array must contain at least one value from the provided list.
`@NonNull Query`	`whereEqualTo(@NonNull String field, @Nullable Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be equal to the specified value.
`@NonNull Query`	`whereEqualTo(@NonNull FieldPath fieldPath, @Nullable Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be equal to the specified value.
`@NonNull Query`	`whereGreaterThan(@NonNull String field, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be greater than the specified value.
`@NonNull Query`	`whereGreaterThan(@NonNull FieldPath fieldPath, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be greater than the specified value.
`@NonNull Query`	`whereGreaterThanOrEqualTo(@NonNull String field, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be greater than or equal to the specified value.
`@NonNull Query`	`whereGreaterThanOrEqualTo( @NonNull FieldPath fieldPath, @NonNull Object value )` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be greater than or equal to the specified value.
`@NonNull Query`	`whereIn(@NonNull String field, @NonNull List<Object> values)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value must equal one of the values from the provided list.
`@NonNull Query`	`whereIn(@NonNull FieldPath fieldPath, @NonNull List<Object> values)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value must equal one of the values from the provided list.
`@NonNull Query`	`whereLessThan(@NonNull String field, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be less than the specified value.
`@NonNull Query`	`whereLessThan(@NonNull FieldPath fieldPath, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be less than the specified value.
`@NonNull Query`	`whereLessThanOrEqualTo(@NonNull String field, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be less than or equal to the specified value.
`@NonNull Query`	`whereLessThanOrEqualTo(@NonNull FieldPath fieldPath, @NonNull Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value should be less than or equal to the specified value.
`@NonNull Query`	`whereNotEqualTo(@NonNull String field, @Nullable Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value does not equal the specified value.
`@NonNull Query`	`whereNotEqualTo(@NonNull FieldPath fieldPath, @Nullable Object value)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value does not equal the specified value.
`@NonNull Query`	`whereNotIn(@NonNull String field, @NonNull List<Object> values)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value does not equal any of the values from the provided list.
`@NonNull Query`	`whereNotIn(@NonNull FieldPath fieldPath, @NonNull List<Object> values)` Creates and returns a new `Query` with the additional filter that documents must contain the specified field and the value does not equal any of the values from the provided list.

Public methods

add

public @NonNull Task<DocumentReference> add(@NonNull Object data)

Adds a new document to this collection with the specified data, assigning it a document ID automatically.

Parameters
`@NonNull Object data`	The data to write to the document (like a Map or a POJO containing the desired document contents).

Returns
`@NonNull Task<DocumentReference>`	A Task that will be resolved with the `DocumentReference` of the newly created document.

document

public @NonNull DocumentReference document()

Returns a DocumentReference pointing to a new document with an auto-generated ID within this collection.

Returns
`@NonNull DocumentReference`	A `DocumentReference` pointing to a new document with an auto-generated ID.

document

public @NonNull DocumentReference document(@NonNull String documentPath)

Gets a DocumentReference instance that refers to the document at the specified path within this collection.

Parameters
`@NonNull String documentPath`	A slash-separated relative path to a document.

Returns
`@NonNull DocumentReference`	The `DocumentReference` instance.

getId

public @NonNull String getId()

Returns
`@NonNull String`	The ID of the collection.

getParent

public @Nullable DocumentReference getParent()

Gets a DocumentReference to the document that contains this collection. Only subcollections are contained in a document. For root collections, returns null.

Returns
`@Nullable DocumentReference`	The `DocumentReference` that contains this collection or `null` if this is a root collection.

getPath

public @NonNull String getPath()

Gets the path of this collection (relative to the root of the database) as a slash-separated string.

Returns
`@NonNull String`	The path of this collection.