firebase.database. Database
The Firebase Database service interface.
Do not call this constructor directly. Instead, use
firebase.database()
.
See Installation & Setup in JavaScript for a full guide on how to use the Firebase Database service.
Property
app
non-null firebase.app.App
The app associated with the Database
service instance.
Example
var app = database.app;
Methods
goOffline
goOffline()
Disconnects from the server (all Database operations will be completed offline).
The client automatically maintains a persistent connection to the Database server, which will remain active indefinitely and reconnect when disconnected. However, the goOffline()
and goOnline()
methods may be used
to control the client connection in cases where a persistent connection is undesirable.
While offline, the client will no longer receive data updates from the Database. However, all Database operations performed locally will continue to immediately fire events, allowing your application to continue behaving normally. Additionally, each operation performed locally will automatically be queued and retried upon reconnection to the Database server.
To reconnect to the Database and begin receiving remote events, see
goOnline()
.
Example
firebase.database().goOffline();
goOnline
goOnline()
Reconnects to the server and synchronizes the offline Database state with the server state.
This method should be used after disabling the active connection with
goOffline()
. Once reconnected, the client will transmit the proper data and fire the appropriate events so that your client "catches up" automatically.
Example
firebase.database().goOnline();
ref
ref(path) returns firebase.database.Reference
Returns a Reference
representing the location in the Database corresponding to the provided path. If no path is provided, the Reference
will point to the root of the Database.
Parameter |
|
---|---|
path |
Optional string Optional path representing the location the returned
|
- Returns
-
non-null firebase.database.Reference
If a path is provided, aReference
pointing to the provided path. Otherwise, aReference
pointing to the root of the Database.
Examples
// Get a reference to the root of the Database
var rootRef = firebase.database().ref();
// Get a reference to the /users/ada node
var adaRef = firebase.database().ref("users/ada");
// The above is shorthand for the following operations:
//var rootRef = firebase.database().ref();
//var adaRef = rootRef.child("users/ada");
refFromURL
refFromURL(url) returns firebase.database.Reference
Returns a Reference
representing the location in the Database corresponding to the provided Firebase URL.
An exception is thrown if the URL is not a valid Firebase Database URL or it has a different domain than the current Database
instance.
Note that all query parameters (orderBy
, limitToLast
, etc.) are ignored and are not applied to the returned Reference
.
Parameter |
|
---|---|
url |
string The Firebase URL at which the returned |
- Returns
-
non-null firebase.database.Reference
AReference
pointing to the provided Firebase URL.
Examples
// Get a reference to the root of the Database
var rootRef = firebase.database().ref("https://<DATABASE_NAME>.firebaseio.com");
// Get a reference to the /users/ada node
var adaRef = firebase.database().ref("https://<DATABASE_NAME>.firebaseio.com/users/ada");