DatabaseReference class
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).
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> -
Fires when children are added.
no setterinherited
-
onChildChanged
→ Stream<
Event> -
Fires when children are changed.
no setterinherited
-
onChildMoved
→ Stream<
Event> -
Fires when children are moved.
no setterinherited
-
onChildRemoved
→ Stream<
Event> -
Fires when children are removed.
previousChildKeyis null.no setterinherited -
onValue
→ Stream<
Event> -
Fires when the data at this location is updated.
previousChildKeyis null.no setterinherited - path → String
-
Slash-delimited path representing the database location of this query.
no setterinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
Methods
-
buildArguments(
) → Map< String, dynamic> -
inherited
-
child(
String path) → DatabaseReference - Gets a DatabaseReference for the location at the specified relative path. The relative path can either be a simple child key (e.g. ‘fred’) or a deeper slash-separated path (e.g. ‘fred/name/first’).
-
endAt(
dynamic value, {String? key}) → Query -
Create a query constrained to only return child nodes with a value less
than or equal to the given value, using the given orderBy directive or
priority as default, and optionally only child nodes with a key less
than or equal to the given key.
inherited
-
equalTo(
dynamic value, {String? key}) → Query -
Create a query constrained to only return child nodes with the given
value(andkey, if provided).inherited -
get(
) → Future< DataSnapshot> -
Gets the most up-to-date result 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. Additionally, while a location is kept synced,
it will not be evicted from the persistent disk cache.
inherited
-
limitToFirst(
int limit) → Query -
Create a query with limit and anchor it to the start of the window.
inherited
-
limitToLast(
int limit) → Query -
Create a query with limit and anchor it to the end of the window.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
once(
) → Future< DataSnapshot> -
Listens for a single value event and then stops listening.
inherited
-
onDisconnect(
) → OnDisconnect -
orderByChild(
String key) → Query -
Generate a view of the data sorted by values of a particular child key.
inherited
-
orderByKey(
) → Query -
Generate a view of the data sorted by key.
inherited
-
orderByPriority(
) → Query -
Generate a view of the data sorted by priority.
inherited
-
orderByValue(
) → Query -
Generate a view of the data sorted by value.
inherited
-
parent(
) → DatabaseReference? - Gets a DatabaseReference for the parent location. If this instance refers to the root of your Firebase Database, it has no parent, and therefore parent() will return null.
-
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 -
Obtains a DatabaseReference corresponding to this query's location.
inherited
-
remove(
) → Future< void> - Remove the data at this Firebase Database location. Any data at child locations will also be deleted.
-
root(
) → DatabaseReference - Gets a FIRDatabaseReference for the root location.
-
runTransaction(
TransactionHandler transactionHandler, {Duration timeout = const Duration(seconds: 5)}) → Future< TransactionResult> - Performs an optimistic-concurrency transactional update to the data at this Firebase Database location.
-
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 -
Create a query constrained to only return child nodes with a value greater
than or equal to the given value, using the given orderBy directive or
priority as default, and optionally only child nodes with a key greater
than or equal to the given key.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
-
update(
Map< String, dynamic> value) → Future<void> -
Update the node with the
value
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited