Use $user or User::instance() instead

Reduced usages of UserInfo

+ Functions create, edit and exists in the discipline model
+ Redirect time switched to 500 ms

That's why a conflict occurs when a class has two functions with the same name.

+ Dynamic factory method was removed (improves static code analysis)
+ One file instead of several: Class/DataArr/Students.php, Model/Admin/Students.php and Model/DataArr/Students.php