Adding custom attributes to django scheema
Once again I have a privilege to answer my own question. So hear is the solution.
Django has a user profile module which is to be turned on by giving the module location in the settings.py 
i.e - 

"AUTH_PROFILE_MODULE = appTitle.UserProfile"

The UserProfile needs to be specified in modules.py specifying the required structure of user profile u need for your app. 
Now doing sync -db django creates the Database table for your user profile and further on the same user profile pysaml adds the value (CustomAttribute) which come on the saml Assertion.
more explanations on this can be found on django documentations too.
If any one still faces any issue please let me know.
I am trying to authenticate my django application written in python with okta IDP. I have almost configured everything at SP side and IDP side too. Now I need to pass a custom variable from IDP which assert SP that user is a publisher,editor or admin and further save this to the django format database (in auth_user_groups table). Anyone have tried doing this, or anyone has idea about this? 
I am able to get the custom variable values by attributes mappings from IDP. But this allows me to save the custom attributes only on the user table. please let me know if i have not made myself clear here about my question.