Unfortunattly "Solanki Shamji" solution is not working. It says " Uncaught TypeError: Cannot read property 'length' of undefined" :( 

Here is the answer:

In the group of your user in settings for example : Human Ressources/Manager or Human Ressources/Emplyees in settings, if you click on it, you will find some thing named "Rules". There, you add:

General:

name:

object: object of your custom module

active: True

Rule definition:

['|', ('employee_id.user_id', '=', user.id), ('employee_id.department_id.manager_id.user_id', '=', user.id)]

and then you add the group of users: Human Ressources/Manager or Human Ressources/Emplyees

i have worked with this to display for each employee only his own payslips.

It works fine