DatabaseReference class abstract
DatabaseReference represents a particular location in your Firebase Database and can be used for reading or writing data to that location.
This class is the starting point for all Firebase Database operations.
After you’ve obtained your first DatabaseReference via
FirebaseDatabase.reference(), you can use it to read data
(ie. onChildAdded), write data (ie. setValue), and to create new
DatabaseReferences (ie. child).
- Implemented types
Constructors
Properties
- hashCode → int
-
The hash code for this object.
no setterinherited
- key → String?
-
Gets the last token in a Firebase Database location (e.g. ‘fred’ in
https://SampleChat.firebaseIO-demo.com/users/fred)
no setter
-
onChildAdded
→ Stream<
Event> -
Streams for 'child_added' events.
no setterinherited
-
onChildChanged
→ Stream<
Event> -
Streams for 'child_changed' events.
no setterinherited
-
onChildMoved
→ Stream<
Event> -
Streams for 'child_moved' events.
no setterinherited
-
onChildRemoved
→ Stream<
Event> -
Streams for 'child_removed' events.
no setterinherited
-
onValue
→ Stream<
Event> -
Streams for 'value' events.
no setterinherited
- path → String
-
Gets the path to this Firebase reference's location.
no setter
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- url → Uri
-
Gets the absolute URL corresponding to this Firebase reference's location.
no setter
Methods
-
child(
String c) → DatabaseReference - Gets a DatabaseReference for the location at the specified relative path.
-
endAt(
dynamic value, {String? key}) → Query -
Creates a Query with the specified ending point. The generated Query
includes children which match the specified ending point. If no arguments
are provided, the ending point will be the end of the data.
inherited
-
equalTo(
dynamic value, {String? key}) → Query -
Creates a Query which includes children which match the specified value.
inherited
-
get(
) → Future -
Convenient method to get the value for this query.
inherited
-
keepSynced(
bool value) → Future< void> -
By calling keepSynced(true) on a location, the data for that location will
automatically be downloaded and kept in sync, even when no listeners are
attached for that location.
inherited
-
limitToFirst(
int limit) → Query -
Generates a new Query object limited to the first certain number of
children.
inherited
-
limitToLast(
int limit) → Query -
Generates a new Query object limited to the last certain number of
children.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
on(
String eventType) → Stream< Event> -
Gets a stream for events of type
eventTypeinherited -
once(
) → Future< DataSnapshot> -
Listens for a single value event and then stops listening.
inherited
-
onDisconnect(
) → OnDisconnect - Getter for onDisconnect.
-
orderByChild(
String child) → Query -
Generates a new Query object ordered by the specified child key.
inherited
-
orderByKey(
) → Query -
Generates a new Query object ordered by key.
inherited
-
orderByPriority(
) → Query -
Generates a new Query object ordered by priority.
inherited
-
orderByValue(
) → Query -
Generates a new Query object ordered by child values.
inherited
-
parent(
) → DatabaseReference? - Gets a DatabaseReference for the parent location.
-
push(
) → DatabaseReference - Generates a new child location using a unique key and returns a DatabaseReference to it. This is useful when the children of a Firebase Database location represent a list of items.
-
reference(
) → DatabaseReference -
Queries are attached to a location in your Firebase. This method will
return a Firebase reference to that location.
inherited
-
remove(
) → Future< void> - Remove the data at this Firebase location. Any data at child locations will also be deleted.
-
root(
) → DatabaseReference - Gets a DatabaseReference for the root location.
-
runTransaction(
TransactionHandler transactionHandler, {Duration timeout = const Duration(seconds: 5)}) → Future< TransactionResult> - Atomically modify the data at this location. Unlike a normal set(), which just overwrites the data regardless of its previous value, runTransaction() is used to modify the existing value to a new value, ensuring there are no conflicts with other clients writing to the same location at the same time.
-
set(
dynamic value, {dynamic priority}) → Future< void> -
Write
valueto the location with the specifiedpriorityif applicable. -
setPriority(
dynamic priority) → Future< void> - Sets a priority for the data at this Firebase Database location.
-
startAt(
dynamic value, {String? key}) → Query -
Creates a Query with the specified starting point. The generated Query
includes children which match the specified starting point. If no arguments
are provided, the starting point will be the beginning of the data.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
-
update(
Map< String, dynamic> value) → Future<void> - Write the enumerated children to this Firebase location. This will only overwrite the children enumerated in the 'value' parameter and will leave others untouched.
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited