Design Pattern

Good Morning ,  I need to implement  a strategy NAV 2016   to enable the posting functionnality  only after validating if the user belong to a specific group of permission

Event the user click on  button post

Then   program  validate if the user belong to one group


if that the case  go to proper table and enable the posting variable  and excute the posting action .



My question should use a design pattern  such observer to make sure is there interaction between the gui(  post button click) or the  and the validate function and the table or use a different design pattern ?


if you have any suggestion for the design pattern and how to implement it let me know .

Regard Rodd!