Backendless Login API¶
Registered users can login using the API described below. The login operation requires two properties: one marked asuser identity and the second is password. Backendless automatically assigns the "AuthenticatedUser"
role to all successfully logged in users. The role can be used to differentiate access to various resources (data in the database, files, messaging channels) between authenticated users and guests.
Non-Blocking API¶
The method call does not block - it returns immediately. The AsyncCallback
argument receives either the response or the fault returned by the Backendless servers.
public void Backendless.UserService.login( String login,
String password,
AsyncCallback<BackendlessUser> callback );
public void Backendless.UserService.login( String login,
String password,
AsyncCallback<BackendlessUser> callback,
boolean stayLoggedIn, );
where:
Argument | Description |
---|---|
login |
a value for a property marked as identity. |
password |
user's password |
callback |
an object which receives either a return value or an error from the server. The class must implement the AsyncCallback<BackendlessUser> interface . |
stayLoggedIn |
requests to store the user's login information so the login form can be skipped next time the user launches the app. |
If the stayLoggedIn
argument is set to true
, use the following API to check if the application has the user login information from the previous runs of the application:
// UserTokenStorageFactory is available in the com.backendless.persistence.local package
String userToken = UserTokenStorageFactory.instance().getStorage().get();
if( userToken != null && !userToken.equals( "" ) )
{ // user login is available, skip the login activity/login form }
Blocking API¶
public BackendlessUser Backendless.UserService.login( String login,
String password,
boolean stayLoggedIn )
throws BackendlessException;
where:
Argument | Description |
---|---|
login |
a value for a property marked as identity. |
password |
user's password |
stayLoggedIn |
requests to store the user's login information so the login form can be skipped next time the user launches the app. |
If the stayLoggedIn
argument is set to true
, use the following API to check if the application has the user login information from the previous runs of the application:
// UserTokenStorageFactory is available in the com.backendless.persistence.local package
String userToken = UserTokenStorageFactory.instance().getStorage().get();
if( userToken != null && !userToken.equals( "" ) )
{ // user login is available, skip the login activity/login form }
Errors¶
The following errors may occur during the Login API call. See the Error Handling section for details on how to retrieve the error code when the server returns an error.
Error Code |
Description |
---|---|
2002 |
Version is disabled or provided wrong application info (application id or secret key) |
3000 |
Login has been disabled for the user account. |
3001 |
Missing login settings, possibly invalid application id or version. |
3002 |
User cannot login because Multiple Logins disabled and there is a logged in user for the account. |
3003 |
Invalid login or password. |
3006 |
Either login or password is an empty string value. |
3034 |
User logins are disabled for the version of the application. |
3036 |
Account locked out due to too many failed logins. |
3038 |
One of the required parameters (application id, version, login or password) is null |
3044 |
Multiple login limit for the same user account has been reached. |
8000 |
Property value exceeds the length limit |
Non-Blocking API Example
¶
// do not forget to call Backendless.initApp in the app initialization code
Backendless.UserService.login( username, password, new AsyncCallback<BackendlessUser>()
{
public void handleResponse( BackendlessUser user )
{
// user has been logged in
}
public void handleFault( BackendlessFault fault )
{
// login failed, to get the error code call fault.getCode()
}
});
Blocking API Example¶
// do not forget to call Backendless.initApp in the app initialization code
BackendlessUser user;
try
{
user = Backendless.UserService.login( username, password );
}
catch( BackendlessException exception )
{
// login failed, to get the error code, call exception.getFault().getCode()
}
Validating User Login¶
The login operation provides a way to persist the user-token
on the client side so it can be used when the application is restarted. This helps in streamlining the user experience since the user of the application does not need to login again. However, when the application restarts, it needs to check if the underlying user token, and hence the user session are still valid. This can be accomplished with the API below:
Non-Blocking API¶
public void Backendless.UserService.isValidLogin( AsyncCallback<Boolean> callback );
Blocking API
¶
public boolean Backendless.UserService.isValidLogin();
If user token is valid, objectId
of the logged in user can be retrieved with the following call:
string currentUserObjectId = UserIdStorageFactory.instance().getStorage().get()
Subsequently the BackendessUser
instance can be obtained with the following API:
Non-blocking call:
Backendless.Data.of( BackendlessUser.class ).findById(
currentUserObjectId,
AsyncCallback<BackendlessUser> callback )
Blocking call:
Backendless.Data.of( BackendlessUser.class ).findById( currentUserObjectId )
Example¶
Log in a user first. Make sure the stayLoggedIn
argument is true.
The value of true
persists the information about the login for the use by subsequent starts/sessions of the application:
Backendless.UserService.login( "batman@backendless.com", "superm@n", true );
Then, check whether the login is valid - see the example below:
Blocking example:
boolean isValidLogin = Backendless.UserService.isValidLogin();
Log.i( "MYAPP", "[SYNC] Is login valid? - " + isValidLogin );
Non-blocking example:
AsyncCallback<Boolean> isValidLoginCallback = new AsyncCallback<Boolean>()
{
@Override
public void handleResponse( Boolean response )
{
Log.i( "MYAPP", "[ASYNC] Is login valid? - " + response );
}
@Override
public void handleFault( BackendlessFault fault )
{
Log.i( "MYAPP", "Error - " + fault );
}
};
Backendless.UserService.isValidLogin( isValidLoginCallback );