Django: Can class-based views accept two forms at a time?

Question

If I have two forms:

class ContactForm(forms.Form):
    name = forms.CharField()
    message = forms.CharField(widget=forms.Textarea)

class SocialForm(forms.Form):
    name = forms.CharField()
    message = forms.CharField(widget=forms.Textarea)

and wanted to use a class based view, and send both forms to the template, is that even possible?

class TestView(FormView):
    template_name = 'contact.html'
    form_class = ContactForm

It seems the FormView can only accept one form at a time. In function based view though I can easily send two forms to my template and retrieve the content of both within the request.POST back.

variables = {'contact_form':contact_form, 'social_form':social_form }
return render(request, 'discussion.html', variables)

Is this a limitation of using class based view (generic views)?

Many Thanks

Solution 1

Here's a scaleable solution. My starting point was this gist,

https://gist.github.com/michelts/1029336

i've enhanced that solution so that multiple forms can be displayed, but either all or an individual can be submitted

https://gist.github.com/jamesbrobb/748c47f46b9bd224b07f

and this is an example usage

class SignupLoginView(MultiFormsView):
    template_name = 'public/my_login_signup_template.html'
    form_classes = {'login': LoginForm,
                    'signup': SignupForm}
    success_url = 'my/success/url'

    def get_login_initial(self):
        return {'email':'[email protected]'}

    def get_signup_initial(self):
        return {'email':'[email protected]'}

    def get_context_data(self, **kwargs):
        context = super(SignupLoginView, self).get_context_data(**kwargs)
        context.update({"some_context_value": 'blah blah blah',
                        "some_other_context_value": 'blah'})
        return context

    def login_form_valid(self, form):
        return form.login(self.request, redirect_url=self.get_success_url())

    def signup_form_valid(self, form):
        user = form.save(self.request)
        return form.signup(self.request, user, self.get_success_url())

and the template looks like this

<form class="login" method="POST" action="{% url 'my_view' %}">
    {% csrf_token %}
    {{ forms.login.as_p }}

    <button name='action' value='login' type="submit">Sign in</button>
</form>

<form class="signup" method="POST" action="{% url 'my_view' %}">
    {% csrf_token %}
    {{ forms.signup.as_p }}

    <button name='action' value='signup' type="submit">Sign up</button>
</form>

An important thing to note on the template are the submit buttons. They have to have their 'name' attribute set to 'action' and their 'value' attribute must match the name given to the form in the 'form_classes' dict. This is used to determine which individual form has been submitted.

Solution 2

By default, class-based views only support a single form per view. But there are other ways to accomplish what you need. But again, this cannot handle both forms at the same time. This will also work with most of the class-based views as well as regular forms.

views.py

class MyClassView(UpdateView):

    template_name = 'page.html'
    form_class = myform1
    second_form_class = myform2
    success_url = '/'

    def get_context_data(self, **kwargs):
        context = super(MyClassView, self).get_context_data(**kwargs)
        if 'form' not in context:
            context['form'] = self.form_class(request=self.request)
        if 'form2' not in context:
            context['form2'] = self.second_form_class(request=self.request)
        return context

    def get_object(self):
        return get_object_or_404(Model, pk=self.request.session['value_here'])

    def form_invalid(self, **kwargs):
        return self.render_to_response(self.get_context_data(**kwargs))

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        if 'form' in request.POST:
            form_class = self.get_form_class()
            form_name = 'form'
        else:
            form_class = self.second_form_class
            form_name = 'form2'

        form = self.get_form(form_class)

        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(**{form_name: form})

template

<form method="post">
    {% csrf_token %}
    .........
    <input type="submit" name="form" value="Submit" />
</form>

<form method="post">
    {% csrf_token %}
    .........
    <input type="submit" name="form2" value="Submit" />
</form>

Solution 3

Its is possible for one class-based view to accept two forms at a time.

view.py

class TestView(FormView):
    template_name = 'contact.html'
    def get(self, request, *args, **kwargs):
        contact_form = ContactForm()
        contact_form.prefix = 'contact_form'
        social_form = SocialForm()
        social_form.prefix = 'social_form'
        # Use RequestContext instead of render_to_response from 3.0
        return self.render_to_response(self.get_context_data({'contact_form': contact_form, 'social_form': social_form}))

    def post(self, request, *args, **kwargs):
        contact_form = ContactForm(self.request.POST, prefix='contact_form')
        social_form = SocialForm(self.request.POST, prefix='social_form ')

        if contact_form.is_valid() and social_form.is_valid():
            ### do something
            return HttpResponseRedirect(>>> redirect url <<<)
        else:
            return self.form_invalid(contact_form,social_form , **kwargs)


    def form_invalid(self, contact_form, social_form, **kwargs):
        contact_form.prefix='contact_form'
        social_form.prefix='social_form'

        return self.render_to_response(self.get_context_data({'contact_form': contact_form, 'social_form': social_form}))

forms.py

from django import forms
from models import Social, Contact
from crispy_forms.helper import FormHelper
from crispy_forms.layout import Submit, Button, Layout, Field, Div
from crispy_forms.bootstrap import (FormActions)

class ContactForm(forms.ModelForm):
    class Meta:
        model = Contact
    helper = FormHelper()
    helper.form_tag = False

class SocialForm(forms.Form):
    class Meta:
        model = Social
    helper = FormHelper()
    helper.form_tag = False

HTML

Take one outer form class and set action as TestView Url

{% load crispy_forms_tags %}
<form action="/testview/" method="post">
  <!----- render your forms here -->
  {% crispy contact_form %}
  {% crispy social_form%}
  <input type='submit' value="Save" />
</form>

Good Luck

Solution 4

I have used a following generic view based on TemplateView:

def merge_dicts(x, y):
    """
    Given two dicts, merge them into a new dict as a shallow copy.
    """
    z = x.copy()
    z.update(y)
    return z


class MultipleFormView(TemplateView):
    """
    View mixin that handles multiple forms / formsets.
    After the successful data is inserted ``self.process_forms`` is called.
    """
    form_classes = {}

    def get_context_data(self, **kwargs):
        context = super(MultipleFormView, self).get_context_data(**kwargs)
        forms_initialized = {name: form(prefix=name)
                             for name, form in self.form_classes.items()}

        return merge_dicts(context, forms_initialized)

    def post(self, request):
        forms_initialized = {
            name: form(prefix=name, data=request.POST)
            for name, form in self.form_classes.items()}

        valid = all([form_class.is_valid()
                     for form_class in forms_initialized.values()])
        if valid:
            return self.process_forms(forms_initialized)
        else:
            context = merge_dicts(self.get_context_data(), forms_initialized)
            return self.render_to_response(context)

    def process_forms(self, form_instances):
        raise NotImplemented

This has the advantage that it is reusable and all the validation is done on the forms themselves.

It is then used as follows:

class AddSource(MultipleFormView):
    """
    Custom view for processing source form and seed formset
    """
    template_name = 'add_source.html'
    form_classes = {
        'source_form': forms.SourceForm,
        'seed_formset': forms.SeedFormset,
    }

    def process_forms(self, form_instances):
        pass # saving forms etc

Solution 5

Use django-superform

This is a pretty neat way to thread a composed form as a single object to outside callers, such as the Django class based views.

from django_superform import FormField, SuperForm

class MyClassForm(SuperForm):
    form1 = FormField(FormClass1)
    form2 = FormField(FormClass2)

In the view, you can use form_class = MyClassForm

In the form __init__() method, you can access the forms using: self.forms['form1']

There is also a SuperModelForm and ModelFormField for model-forms.

In the template, you can access the form fields using: {{ form.form1.field }}. I would recommend aliasing the form using {% with form1=form.form1 %} to avoid rereading/reconstructing the form all the time.

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