ControlContext :: hasData - Exists valid data source for the control?
The function checks, whether a valid data source has been assigned to the control or not. Specially, user-defined data sources that have not yet been set by calling setProperty() may be uninitialized and will cause an exception when calling property() .
Return value: State of function return ( bool )
A State true indicates, that the function was executed successfully. Otherwise state is false .