To make it possible to only register users who provided invite code and log in only users which was already registered

signup_codes_for_social_auth.py

@render_to("account/signup.html")
def register(request, backend):
    """Start authentication process"""
    
    code = request.GET.get("code")

    signup_code = check_signup_code(code)
    if signup_code:
        request.session['signup_code'] = signup_code
        return auth(request, backend)
    else:
        return ({
            "code": code,
            },
            "signup_codes/failure.html"
        )

def complete(request, backend):
    """Authentication complete view, override this view if transaction
    management doesn't suit your needs."""

    signup_code = check_signup_code(request.session.get('signup_code', ''))

    if signup_code:
        del request.session['signup_code']
        return simple_complete(request, backend)
    else:
        create_users = getattr(settings, 'SOCIAL_AUTH_CREATE_USERS', True)
        settings.SOCIAL_AUTH_CREATE_USERS = False
        result = simple_complete(request, backend)
        settings.SOCIAL_AUTH_CREATE_USERS = create_users
        return result