[python] Proper way to handle multiple forms on one page in Django

I have a template page expecting two forms. If I just use one form, things are fine as in this typical example:

if request.method == 'POST':
    form = AuthorForm(request.POST,)
    if form.is_valid():
        form.save()
        # do something.
else:
    form = AuthorForm()

If I want to work with multiple forms however, how do I let the view know that I'm submitting only one of the forms and not the other (i.e. it's still request.POST but I only want to process the form for which the submit happened)?

This is the solution based on the answer where expectedphrase and bannedphrase are the names of the submit buttons for the different forms and expectedphraseform and bannedphraseform are the forms.

if request.method == 'POST':
    if 'bannedphrase' in request.POST:
        bannedphraseform = BannedPhraseForm(request.POST, prefix='banned')
        if bannedphraseform.is_valid():
            bannedphraseform.save()
        expectedphraseform = ExpectedPhraseForm(prefix='expected')
    elif 'expectedphrase' in request.POST:
        expectedphraseform = ExpectedPhraseForm(request.POST, prefix='expected')
        if expectedphraseform.is_valid():
            expectedphraseform.save() 
        bannedphraseform = BannedPhraseForm(prefix='banned')
else:
    bannedphraseform = BannedPhraseForm(prefix='banned')
    expectedphraseform = ExpectedPhraseForm(prefix='expected')

Wanted to share my solution where Django Forms are not being used. I have multiple form elements on a single page and I want to use a single view to manage all the POST requests from all the forms.

What I've done is I have introduced an invisible input tag so that I can pass a parameter to the views to check which form has been submitted.

<form method="post" id="formOne">
    {% csrf_token %}
   <input type="hidden" name="form_type" value="formOne">

    .....
</form>

.....

<form method="post" id="formTwo">
    {% csrf_token %}
    <input type="hidden" name="form_type" value="formTwo">
   ....
</form>

views.py

def handlemultipleforms(request, template="handle/multiple_forms.html"):
    """
    Handle Multiple <form></form> elements
    """
    if request.method == 'POST':
        if request.POST.get("form_type") == 'formOne':
            #Handle Elements from first Form
        elif request.POST.get("form_type") == 'formTwo':
            #Handle Elements from second Form

Django's class based views provide a generic FormView but for all intents and purposes it is designed to only handle one form.

One way to handle multiple forms with same target action url using Django's generic views is to extend the 'TemplateView' as shown below; I use this approach often enough that I have made it into an Eclipse IDE template.

class NegotiationGroupMultifacetedView(TemplateView):
    ### TemplateResponseMixin
    template_name = 'offers/offer_detail.html'

    ### ContextMixin 
    def get_context_data(self, **kwargs):
        """ Adds extra content to our template """
        context = super(NegotiationGroupDetailView, self).get_context_data(**kwargs)

        ...

        context['negotiation_bid_form'] = NegotiationBidForm(
            prefix='NegotiationBidForm', 
            ...
            # Multiple 'submit' button paths should be handled in form's .save()/clean()
            data = self.request.POST if bool(set(['NegotiationBidForm-submit-counter-bid',
                                              'NegotiationBidForm-submit-approve-bid',
                                              'NegotiationBidForm-submit-decline-further-bids']).intersection(
                                                    self.request.POST)) else None,
            )
        context['offer_attachment_form'] = NegotiationAttachmentForm(
            prefix='NegotiationAttachment', 
            ...
            data = self.request.POST if 'NegotiationAttachment-submit' in self.request.POST else None,
            files = self.request.FILES if 'NegotiationAttachment-submit' in self.request.POST else None
            )
        context['offer_contact_form'] = NegotiationContactForm()
        return context

    ### NegotiationGroupDetailView 
    def post(self, request, *args, **kwargs):
        context = self.get_context_data(**kwargs)

        if context['negotiation_bid_form'].is_valid():
            instance = context['negotiation_bid_form'].save()
            messages.success(request, 'Your offer bid #{0} has been submitted.'.format(instance.pk))
        elif context['offer_attachment_form'].is_valid():
            instance = context['offer_attachment_form'].save()
            messages.success(request, 'Your offer attachment #{0} has been submitted.'.format(instance.pk))
                # advise of any errors

        else 
            messages.error('Error(s) encountered during form processing, please review below and re-submit')

        return self.render_to_response(context)

The html template is to the following effect:

...

<form id='offer_negotiation_form' class="content-form" action='./' enctype="multipart/form-data" method="post" accept-charset="utf-8">
    {% csrf_token %}
    {{ negotiation_bid_form.as_p }}
    ...
    <input type="submit" name="{{ negotiation_bid_form.prefix }}-submit-counter-bid" 
    title="Submit a counter bid"
    value="Counter Bid" />
</form>

...

<form id='offer-attachment-form' class="content-form" action='./' enctype="multipart/form-data" method="post" accept-charset="utf-8">
    {% csrf_token %}
    {{ offer_attachment_form.as_p }}

    <input name="{{ offer_attachment_form.prefix }}-submit" type="submit" value="Submit" />
</form>

...

I needed multiple forms that are independently validated on the same page. The key concepts I was missing were 1) using the form prefix for the submit button name and 2) an unbounded form does not trigger validation. If it helps anyone else, here is my simplified example of two forms AForm and BForm using TemplateView based on the answers by @adam-nelson and @daniel-sokolowski and comment by @zeraien (https://stackoverflow.com/a/17303480/2680349):

# views.py
def _get_form(request, formcls, prefix):
    data = request.POST if prefix in request.POST else None
    return formcls(data, prefix=prefix)

class MyView(TemplateView):
    template_name = 'mytemplate.html'

    def get(self, request, *args, **kwargs):
        return self.render_to_response({'aform': AForm(prefix='aform_pre'), 'bform': BForm(prefix='bform_pre')})

    def post(self, request, *args, **kwargs):
        aform = _get_form(request, AForm, 'aform_pre')
        bform = _get_form(request, BForm, 'bform_pre')
        if aform.is_bound and aform.is_valid():
            # Process aform and render response
        elif bform.is_bound and bform.is_valid():
            # Process bform and render response
        return self.render_to_response({'aform': aform, 'bform': bform})

# mytemplate.html
<form action="" method="post">
    {% csrf_token %}
    {{ aform.as_p }}
    <input type="submit" name="{{aform.prefix}}" value="Submit" />
    {{ bform.as_p }}
    <input type="submit" name="{{bform.prefix}}" value="Submit" />
</form>

This is a bit late, but this is the best solution I found. You make a look-up dictionary for the form name and its class, you also have to add an attribute to identify the form, and in your views you have to add it as a hidden field, with the form.formlabel.

# form holder
form_holder = {
    'majeur': {
        'class': FormClass1,
    },
    'majsoft': {
        'class': FormClass2,
    },
    'tiers1': {
        'class': FormClass3,
    },
    'tiers2': {
        'class': FormClass4,
    },
    'tiers3': {
        'class': FormClass5,
    },
    'tiers4': {
        'class': FormClass6,
    },
}

for key in form_holder.keys():
    # If the key is the same as the formlabel, we should use the posted data
    if request.POST.get('formlabel', None) == key:
        # Get the form and initate it with the sent data
        form = form_holder.get(key).get('class')(
            data=request.POST
        )

        # Validate the form
        if form.is_valid():
            # Correct data entries
            messages.info(request, _(u"Configuration validée."))

            if form.save():
                # Save succeeded
                messages.success(
                    request,
                    _(u"Données enregistrées avec succès.")
                )
            else:
                # Save failed
                messages.warning(
                    request,
                    _(u"Un problème est survenu pendant l'enregistrement "
                      u"des données, merci de réessayer plus tard.")
                )
        else:
            # Form is not valid, show feedback to the user
            messages.error(
                request,
                _(u"Merci de corriger les erreurs suivantes.")
            )
    else:
        # Just initiate the form without data
        form = form_holder.get(key).get('class')(key)()

    # Add the attribute for the name
    setattr(form, 'formlabel', key)

    # Append it to the tempalte variable that will hold all the forms
    forms.append(form)

I hope this will help in the future.

Here is simple way to handle the above.

In Html Template we put Post

<form action="/useradd/addnewroute/" method="post" id="login-form">{% csrf_token %}

<!-- add details of form here-->
<form>
<form action="/useradd/addarea/" method="post" id="login-form">{% csrf_token %}

<!-- add details of form here-->

<form>

In View

   def addnewroute(request):
      if request.method == "POST":
         # do something



  def addarea(request):
      if request.method == "POST":
         # do something

In URL Give needed info like

urlpatterns = patterns('',
url(r'^addnewroute/$', views.addnewroute, name='addnewroute'),
url(r'^addarea/', include('usermodules.urls')),

A method for future reference is something like this. bannedphraseform is the first form and expectedphraseform is the second. If the first one is hit, the second one is skipped (which is a reasonable assumption in this case):

if request.method == 'POST':
    bannedphraseform = BannedPhraseForm(request.POST, prefix='banned')
    if bannedphraseform.is_valid():
        bannedphraseform.save()
else:
    bannedphraseform = BannedPhraseForm(prefix='banned')

if request.method == 'POST' and not bannedphraseform.is_valid():
    expectedphraseform = ExpectedPhraseForm(request.POST, prefix='expected')
    bannedphraseform = BannedPhraseForm(prefix='banned')
    if expectedphraseform.is_valid():
        expectedphraseform.save()

else:
    expectedphraseform = ExpectedPhraseForm(prefix='expected')

view:

class AddProductView(generic.TemplateView):
template_name = 'manager/add_product.html'

    def get(self, request, *args, **kwargs):
    form = ProductForm(self.request.GET or None, prefix="sch")
    sub_form = ImageForm(self.request.GET or None, prefix="loc")
    context = super(AddProductView, self).get_context_data(**kwargs)
    context['form'] = form
    context['sub_form'] = sub_form
    return self.render_to_response(context)

def post(self, request, *args, **kwargs):
    form = ProductForm(request.POST,  prefix="sch")
    sub_form = ImageForm(request.POST, prefix="loc")
    ...

template:

{% block container %}
<div class="container">
    <br/>
    <form action="{% url 'manager:add_product' %}" method="post">
        {% csrf_token %}
        {{ form.as_p }}
        {{ sub_form.as_p }}
        <p>
            <button type="submit">Submit</button>
        </p>
    </form>
</div>
{% endblock %}

Based on this answer by @ybendana:

Again, we use is_bound to check if the form is capable of validation. See this section of the documentation:

Bound and unbound forms

A Form instance is either bound to a set of data, or unbound.

• If it’s bound to a set of data, it’s capable of validating that data and rendering the form as HTML with the data displayed in the HTML.
• If it’s unbound, it cannot do validation (because there’s no data to validate!), but it can still render the blank form as HTML.

We use a list of tuples for form objects and their details allowing for more extensibility and less repetition.

However, instead of overriding get(), we override get_context_data() to make inserting a new, blank instance of the form (with prefix) into the response the default action for any request. In the context of a POST request, we override the post() method to:

1. Use the prefix to check if each form has been submitted
2. Validate the forms that have been submitted
3. Process the valid forms using the cleaned_data
4. Return any invalid forms to the response by overwriting the context data

# views.py

class MultipleForms(TemplateResponseMixin, ContextMixin, View):

    form_list = [ # (context_key, formcls, prefix)
        ("form_a", FormA, "prefix_a"),
        ("form_b", FormB, "prefix_b"),
        ("form_c", FormC, "prefix_c"),
        ...
        ("form_x", FormX, "prefix_x"),
    ]

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        # Add blank forms to context with prefixes
        for context_key, formcls, prefix in self.form_list:
            context[context_key] = formcls(prefix=prefix)
        return context

    def post(self, request, *args, **kwargs):
        # Get object and context
        self.object = self.get_object()
        context = self.get_context_data(object=self.object)
        # Process forms
        for context_key, formcls, prefix in self.form_list:
            if prefix in request.POST:
                # Get the form object with prefix and pass it the POST data to \
                # validate and clean etc.
                form = formcls(request.POST, prefix=prefix)
                if form.is_bound:
                    # If the form is bound (i.e. it is capable of validation)  \
                    # check the validation
                    if form.is_valid():
                        # call the form's save() method or do whatever you     \
                        # want with form.cleaned_data
                        form.save()
                    else:
                        # overwrite context data for this form so that it is   \
                        # returned to the page with validation errors
                        context[context_key] = form
        # Pass context back to render_to_response() including any invalid forms
        return self.render_to_response(context)
        

This method allows repeated form entries on the same page, something I found did not work with @ybendana's answer.

I believe it wouldn't be masses more work to fold this method into a Mixin class, taking the form_list object as an attribute and hooking get_context_data() and post() as above.

Edit: This already exists. See this repository.

NB: This method required TemplateResponseMixin for render_to_response() and ContextMixin for get_context_data() to work. Either use these Mixins or a CBV that descends from them.

if request.method == 'POST':
    expectedphraseform = ExpectedphraseForm(request.POST)
    bannedphraseform = BannedphraseForm(request.POST)
    if expectedphraseform.is_valid():
        expectedphraseform.save()
        return HttpResponse("Success")
    if bannedphraseform.is_valid():
        bannedphraseform.save()
        return HttpResponse("Success")
else:
    bannedphraseform = BannedphraseForm()
    expectedphraseform = ExpectedphraseForm()
return render(request, 'some.html',{'bannedphraseform':bannedphraseform, 'expectedphraseform':expectedphraseform})

This worked for me accurately as I wanted. This Approach has a single problem that it validates both the form's errors. But works Totally fine.

If you are using approach with class-based views and different 'action' attrs i mean

Put different URLs in the action for the two forms. Then you'll have two different view functions to deal with the two different forms.

You can easily handle errors from different forms using overloaded get_context_data method, e.x:

views.py:

class LoginView(FormView):
    form_class = AuthFormEdited
    success_url = '/'
    template_name = 'main/index.html'

    def dispatch(self, request, *args, **kwargs):
        return super(LoginView, self).dispatch(request, *args, **kwargs)

    ....

    def get_context_data(self, **kwargs):
        context = super(LoginView, self).get_context_data(**kwargs)
        context['login_view_in_action'] = True
        return context

class SignInView(FormView):
    form_class = SignInForm
    success_url = '/'
    template_name = 'main/index.html'

    def dispatch(self, request, *args, **kwargs):
        return super(SignInView, self).dispatch(request, *args, **kwargs)

    .....

    def get_context_data(self, **kwargs):
        context = super(SignInView, self).get_context_data(**kwargs)
        context['login_view_in_action'] = False
        return context

template:

<div class="login-form">
<form action="/login/" method="post" role="form">
    {% csrf_token %}
    {% if login_view_in_action %}
        {% for e in form.non_field_errors %}
            <div class="alert alert-danger alert-dismissable">
                {{ e }}
                <a class="panel-close close" data-dismiss="alert">×</a>
            </div>
        {% endfor %}
    {% endif %}
    .....
    </form>
</div>

<div class="signin-form">
<form action="/registration/" method="post" role="form">
    {% csrf_token %}
    {% if not login_view_in_action %}
        {% for e in form.non_field_errors %}
            <div class="alert alert-danger alert-dismissable">
                {{ e }}
                <a class="panel-close close" data-dismiss="alert">×</a>
            </div>
        {% endfor %}
    {% endif %}
   ....
  </form>
</div>