Thanks Tom,
it worked.
Also I am using django-filter package for filtering. So I need to convert timestamp here too.
I did override __init__ method of django_filters.FilterSet to achieve this. And I'm modifying querydict (qd = args[0].copy()) before I pass it to super class.
Is it the right way to that?
One more question, What would you prefer to use between 'iso-8601' and unix-timestamp? And Why?