java.lang.Object | ||
↳ | com.google.firebase.database.Query | |
↳ | com.google.firebase.database.DatabaseReference |
A Firebase reference represents a particular location in your Database and can be used for reading or writing data to that Database location.
This class is the starting point for all Database operations. After you've initialized it with a URL, you can use it to read data, write data, and to create new DatabaseReferences.
Nested Classes | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
DatabaseReference.CompletionListener | This interface is used as a method of being notified when an operation has been acknowledged by the Database servers and can be considered complete |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Get a reference to location relative to this one
| |||||||||||
Gets the Database instance associated with this reference.
| |||||||||||
Manually disconnect the Firebase Database client from the server and disable automatic
reconnection.
| |||||||||||
Manually reestablish a connection to the Firebase Database server and enable automatic
reconnection.
| |||||||||||
Provides access to disconnect operations at this location
| |||||||||||
Create a reference to an auto-generated child location.
| |||||||||||
Set the value at this location to 'null'
| |||||||||||
Set the value at this location to 'null'
| |||||||||||
Run a transaction on the data at this location.
| |||||||||||
Run a transaction on the data at this location.
| |||||||||||
Set a priority for the data at this Database location.
| |||||||||||
Set a priority for the data at this Database location.
| |||||||||||
Set the data and priority to the given values.
| |||||||||||
Set the data at this location to the given value.
| |||||||||||
Set the data and priority to the given values.
| |||||||||||
Set the data at this location to the given value.
| |||||||||||
Update the specific child keys to the specified values.
| |||||||||||
Update the specific child keys to the specified values.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
![]() | |||||||||||
![]() |
Get a reference to location relative to this one
Parameters | |
---|---|
pathString |
String :
The relative path from this reference to the new one that should be created |
Returns | |
---|---|
DatabaseReference |
A new DatabaseReference to the given path |
Parameters | |
---|---|
other |
Object
|
Returns | |
---|---|
boolean |
Gets the Database instance associated with this reference.
Returns | |
---|---|
FirebaseDatabase |
The Database object for this reference. |
Returns | |
---|---|
String |
The last token in the location pointed to by this reference |
Returns | |
---|---|
DatabaseReference |
A DatabaseReference to the parent location, or null if this instance references the root location |
Returns | |
---|---|
DatabaseReference |
A reference to the root location of this Firebase Database |
Manually disconnect the Firebase Database client from the server and disable automatic reconnection.
Note: Invoking this method will impact all Firebase Database connections.
Manually reestablish a connection to the Firebase Database server and enable automatic reconnection.
Note: Invoking this method will impact all Firebase Database connections.
Returns | |
---|---|
int |
Provides access to disconnect operations at this location
Returns | |
---|---|
OnDisconnect |
An object for managing disconnect operations at this location |
Create a reference to an auto-generated child location. The child key is generated client-side and incorporates an estimate of the server's time for sorting purposes. Locations generated on a single client will be sorted in the order that they are created, and will be sorted approximately in order across all clients.
Returns | |
---|---|
DatabaseReference |
A DatabaseReference pointing to the new location |
Set the value at this location to 'null'
Parameters | |
---|---|
listener |
DatabaseReference.CompletionListener :
A listener that will be triggered when the operation is complete
|
Run a transaction on the data at this location. For more information on running transactions,
see Transaction.Handler
.
Parameters | |
---|---|
handler |
Transaction.Handler :
An object to handle running the transaction |
fireLocalEvents |
boolean :
Defaults to true. If set to false, events will only be fired for the
final result state of the transaction, and not for any intermediate states
|
Run a transaction on the data at this location. For more information on running transactions,
see Transaction.Handler
.
Parameters | |
---|---|
handler |
Transaction.Handler :
An object to handle running the transaction
|
Set a priority for the data at this Database location. Priorities can be used to provide a
custom ordering for the children at a location (if no priorities are specified, the children
are ordered by key).
You cannot set a priority on an empty location. For this reason setValue(data, priority) should
be used when setting initial data with a specific priority and setPriority should be used when
updating the priority of existing data.
Children are sorted based on this priority using the following rules:
Parameters | |
---|---|
priority |
Object :
The priority to set at the specified location. |
listener |
DatabaseReference.CompletionListener :
A listener that will be triggered with results of the operation
|
Set a priority for the data at this Database location. Priorities can be used to provide a
custom ordering for the children at a location (if no priorities are specified, the children
are ordered by key).
You cannot set a priority on an empty location. For this reason setValue(data, priority) should
be used when setting initial data with a specific priority and setPriority should be used when
updating the priority of existing data.
Children are sorted based on this priority using the following rules:
Parameters | |
---|---|
priority |
Object :
The priority to set at the specified location. |
Returns | |
---|---|
Task<Void> |
The Task for this operation.
|
Set the data and priority to the given values. The native types accepted by this method for the value correspond to the JSON types:
Map<String, MyPOJO>
, as well as null values.
Parameters | |
---|---|
value |
Object :
The value to set at this location |
priority |
Object :
The priority to set at this location |
listener |
DatabaseReference.CompletionListener :
A listener that will be triggered with the results of the operation
|
Set the data at this location to the given value. Passing null to setValue() will delete the data at the specified location. The native types accepted by this method for the value correspond to the JSON types:
Map<String, MyPOJO>
, as well as null values.
Parameters | |
---|---|
value |
Object :
The value to set at this location |
listener |
DatabaseReference.CompletionListener :
A listener that will be triggered with the results of the operation
|
Set the data and priority to the given values. Passing null to setValue() will delete the data at the specified location. The native types accepted by this method for the value correspond to the JSON types:
Map<String, MyPOJO>
, as well as null values.
Parameters | |
---|---|
value |
Object :
The value to set at this location |
priority |
Object :
The priority to set at this location |
Returns | |
---|---|
Task<Void> |
The Task for this operation.
|
Set the data at this location to the given value. Passing null to setValue() will delete the data at the specified location. The native types accepted by this method for the value correspond to the JSON types:
Map<String, MyPOJO>
, as well as null values.
Parameters | |
---|---|
value |
Object :
The value to set at this location |
Returns | |
---|---|
Task<Void> |
The Task for this operation.
|
Returns | |
---|---|
String |
The full location url for this reference |
Update the specific child keys to the specified values. Passing null in a map to updateChildren() will remove the value at the specified location.
Parameters | |
---|---|
update |
Map :
The paths to update and their new values |
listener |
DatabaseReference.CompletionListener :
A listener that will be triggered with results of the operation
|