Fatal Error: Undefined Class Constant 'self::type_String'

[zelakioui]

I am developing a module in prestashop 1.6. i extend AdminController class, everything is nice.but when i want to display the form that permit to add new instance an error message is displayed :

Fatal error: Undefined class constant 'self::TYPE_STRING' in C:\xampp\htdocs\prestashop\classes\controller\AdminController.php on line 1418

[tuk66]

TYPE_STRING is a constant defined in the ObjectModelCore class.You can use self::TYPE_STRING only in a module.

[zelakioui]

I use it just in my model, but i declare my model in adminController by this line $this->className.