Showing different forms for user type with Django/Python in views.py

Question

I have 4 user account types, realtor, insurance broker, auto insurance agent, and mortgage broker. Each one of the users will have a different form for each to submit. I have the following in views.py to render the form:

def _get_form(profile, postdata=None):
    # @TODO - come up with a better solution to render forms on user types than this.
    form = None

    if profile.affiliate_type == UserProfile.INSURANCE_BROKER:
        if postdata:
            form = InsuranceBrokerForm(postdata, instance=profile)
        else:
            form = InsuranceBrokerForm(instance=profile)
    elif profile.affiliate_type == UserProfile.AUTO_DEALERSHIP:
        if postdata:
            form = AutoDealershipForm(postdata, instance=profile)
        else:
            form = AutoDealershipForm(instance=profile)
        form = AutoDealershipForm
    elif profile.affiliate_type == UserProfile.MORTGAGE_BROKER:
        if postdata:
            form = MortgageBrokerForm(postdata, instance=profile)
        else:
            form = MortgageBrokerForm(instance=profile)
    elif profile.affiliate_type == UserProfile.REALTOR:
        if postdata:
            form = RealtorForm(postdata, instance=profile)
        else:
            form = RealtorForm(instance=profile)
    return form

and it's being used like so:

@login_required
def affiliate_form(request, template_name="affiliates/affiliate_form.html"):
    user = request.user
    profile = get_object_or_404(UserProfile, user=user)
    form = _get_form(profile)
    if profile.user != user:
        return HttpResponseForbidden("Forbidden. Please try again.")
    if request.method == 'POST':
        postdata = request.POST.copy()
        form = _get_form(postdata)
        if form.is_valid():
            form.save()
            messages.success(request, 'Your lead has been created.')
            url = urlresolvers.reverse('affiliates')
            return redirect(url)
    else:
        form = _get_form(profile)

    return render(request, template_name, {
        'form': form
    })

As you can see, I am calling _get_form(profile) but this seems dirty. Is there a cleaner way to go about this?

Answer 1

Dicts are good for lookups

When encountering stacked ifs that are all alike, I tend to pickup a dict and try to put it to good use. One way to structure the variable parts of your routine is with something like:

user_form_types = {
    UserProfile.INSURANCE_BROKER: InsuranceBrokerForm,
    UserProfile.AUTO_DEALERSHIP: AutoDealershipForm,
    UserProfile.MORTGAGE_BROKER: MortgageBrokerForm,
    UserProfile.REALTOR: RealtorForm,
}

This one structure allows the variability in the routine to be described in a manner that makes it easy to read and understand that variability, and easy to use the resulting data.

Using data as code

Since Python makes it easy to reference a class and then instantiate it, the dict can be used, and the routine can be boiled down to simply:

user_form_type = user_form_types.get(profile.affiliate_type)
if not user_form_type:
    form = None
else:
    if postdata:
        form = user_form_type(postdata, instance=profile)
    else:
        form = user_form_type(instance=profile)
return form

Entire Recast Routine

def _get_form(profile, postdata=None):

    user_types = {
        UserProfile.INSURANCE_BROKER: InsuranceBrokerForm,
        UserProfile.AUTO_DEALERSHIP: AutoDealershipForm,
        UserProfile.MORTGAGE_BROKER: MortgageBrokerForm,
        UserProfile.REALTOR: RealtorForm,
    }

    user_form_type = user_types.get(profile.affiliate_type)
    if not user_form_type:
        form = None
    else:
        if postdata:
            form = user_form_type(postdata, instance=profile)
        else:
            form = user_form_type(instance=profile)
    return form