title: How to customize admin filter in Django 1.4
body: <p>I am a newbie in Python and Django Development, I learned a lot from the easy read examples provided by the community. But recently I want to implement a customized admin filter for the admin console shipped with Django. I searched a lot and only found some out-of-date approaches to get it done. Such as:
  <a href="https://stackoverflow.com/questions/991926/custom-filter-in-django-admin-on-django-1-3-or-below">Custom Filter in Django Admin on Django 1.3 or below</a></p>
  
  <p>I tried to read the source code for the filters module in 'django.contrib.admin' app, but unfortunately I can hardly understand the rationale behind the codes. So I wonder whether some kind people could supply some examples or references to this issue --- How to customize admin filter in Django 1.4 ?</p>
  
  <p>Thanks in advance！</p>