Sample custom pipeline for django-social-auth and Facebook backend. Goal is to ask more info to the user before creating the account and the related Customer model.

social.py

# settings.py
FACEBOOK_EXTENDED_PERMISSIONS = ['email', 'user_birthday', 'user_location']
SOCIAL_AUTH_PIPELINE = (
    'social_auth.backends.pipeline.social.social_auth_user',
    'social_auth.backends.pipeline.user.get_username',
    'social_auth.backends.pipeline.misc.save_status_to_session',
    'web.facebook.check_registered',
    'social_auth.backends.pipeline.user.create_user',
    'web.facebook.check_profile',
    'social_auth.backends.pipeline.social.associate_user',
    'social_auth.backends.pipeline.social.load_extra_data',
    'social_auth.backends.pipeline.user.update_user_details'
)

# facebook.py
def check_registered(*args, **kwargs):
    ''' check that the user completed the registration form '''
    log.info('check if user registered')
    request = kwargs.get('request')
    has_registered = request.session.get('register_data')
    if has_registered:
        log.info('user registration complete')
        return None
    return redirect('register')


def check_profile(*args, **kwargs):
    ''' check that the user have an existing profile '''
    log.info('check if user profile exists')
    request = kwargs.get('request')
    customer_data = request.session.get('register_data')
    customer, is_new = models.Customer.objects.get_or_create(user=kwargs.get('user'), defaults=customer_data)
    return {
        'customer':customer
    }
    

class RegisterForm(forms.ModelForm):
    ''' simple ModelForm with some additionnal fields (birthdate, gender, city...) '''
    class Meta:
        model = models.Customer
        exclude = ('user',)

    
def register_form(request):
    ''' when not registered, user is redirected to this form '''
    request.session['register_data'] = False
    pipeline_session_key = setting('SOCIAL_AUTH_PARTIAL_PIPELINE_KEY', 'partial_pipeline')
    form = None
    if request.method == 'POST':
        form = RegisterForm(request.POST)
        if form.is_valid():
            # form is valid, go next step
            request.session['register_data'] = form.cleaned_data 
            backend = request.session[pipeline_session_key]['backend']
            return redirect('socialauth_complete', backend=backend)

    template_data = {}

    if not form:
        # initiate form with facebook values if any
        user_data = request.session.get(pipeline_session_key, {}).get('kwargs', {}).get('response', {})
        if not user_data:
             return redirect('socialauth_complete', backend=backend)
        initial_values = {
            'email': user_data.get('email'),
            'first_name': user_data.get('first_name'),
            'last_name': user_data.get('last_name'),
            'city': user_data.get('location', {}).get('name', '').split(',')[0],
            'birthdate': user_data.get('birthday'),
            'gender': 'Mme' if user_data.get('gender') == 'female' else 'M',
        }
        template_data['form_values'] = initial_values
        form = RegisterForm(initial=initial_values)

    tpl = Template('''
        <form action="" method="POST">
            {% csrf_token %}
            <p>
                {{ form.as_ul }}
            </p>
            <input type="submit" value="Send" />
        </form>''')

    template_data['form'] = form

    return HttpResponse(tpl.render(RequestContext(request, template_data)))