Updating Context Data In Formview Form_valid Method?

October 23, 2024 Post a Comment

I have a class QuestionView which is derived from the FormView class. Here is a code snippet to explain my problem: class QuestionView(FormView): ... context_var1 = y

Solution 1:

I do this with form_invalid. Here's how I do it:

from django.views.generic import FormView

classContextFormView(FormView):
    defget(self, request, *args, **kwargs):
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        context = self.get_context_data(**kwargs)
        context['form'] = form
        return self.render_to_response(context)

    defpost(self, request, *args, **kwargs):
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form, **kwargs)

    defform_invalid(self, form, **kwargs):
        context = self.get_context_data(**kwargs)
        context['form'] = form
        return self.render_to_response(context)

You could do the same but for form_valid. Normally the body of form_valid looks like this:

defform_valid(self, form):
    return HttpResponseRedirect(self.get_success_url())

You would have to override both post and form_valid, because post calls form_valid.

defpost(self, request, *args, **kwargs):
    form_class = self.get_form_class()
    form = self.get_form(form_class)
    if form.is_valid():
        returnself.form_valid(form, **kwargs)
    else:returnself.form_invalid(form, **kwargs)

defform_valid(self, form, **kwargs):
    # take some other action herereturn HttpResponseRedirect(self.get_success_url())

oh and just to clarify, the reason this problem exists is that the ProcessFormView class's get method is broken. It normally looks like this:

defget(self, request, *args, **kwargs):
    form_class = self.get_form_class()
    form = self.get_form(form_class)
    returnself.render_to_response(self.get_context_data(form=form))

It just throws the kwargs away (._.)

Solution 2:

In Django 2.0.1 you can insert context data by overriding either get_context_data or form_invalid.

In your case you could do one of the following overrides:

classQuestionView(FormView):
    ...

    defform_invalid(self, form):
        """If the form is invalid, render the invalid form."""return self.render_to_response(
            self.get_context_data(
                form=form, 
                context_key=some_value
            )
        )

Or:

classQuestionView(FormView):
    ...

    defget_context_data(self, **kwargs):
        if'context_key'notinkwargs:# set value if not present
            kwargs['context_key'] = some_value
        returnsuper().get_context_data(**kwargs)

Django 2.0.1 inserts under the hood the form into the kwargs of get_context_data.

# File: django.views.generic.editclassFormMixin(ContextMixin):
    ...

    defform_valid(self, form):
        """If the form is valid, redirect to the supplied URL."""return HttpResponseRedirect(self.get_success_url())

    defform_invalid(self, form):
        """If the form is invalid, render the invalid form."""return self.render_to_response(self.get_context_data(form=form))

    defget_context_data(self, **kwargs):
        """Insert the form into the context dict."""if'form'notin kwargs:
            kwargs['form'] = self.get_form()
        returnsuper().get_context_data(**kwargs)

Solution 3:

In views.py

classUploadTest(FormView):
    template_name = 'test.html'
    ....
    plus_context = dict()

    defform_valid(self, form):
        ...
        self.plus_context['you_want_context'] = value
        ...
        returnsuper(UploadTest, self).form_valid(form)

    defget_context_data(self, **kwargs):
        context = super(UploadTest, self).get_context_data(**kwargs)
        context['plus_context_key'] = self.plus_context
        return context

In test.html

<html>
    ....
    <body>
    ....
    // first post can not get plus_context_key
    {% if plus_context_key %}
        {{ plus_context_key.you_want_context }}
    {% endif %}    
    </body>
</html>

I just figure out this way in Django 1.10.3. Hope can help you

Solution 4:

Maybe you can use this approach:

classSomeView(View):defpost(self, request):
        my_form = MyForm(request.POST)
        if my_form.is_valid():
            context['foo'] = 'bar'return render(request, 'valid/path.html', context)

Solution 5:

Pass plus_context just if save successfull:

classSomeUpdateView(UpdateView):
    ...
    success_url = reverse_lazy('SomeUpdateView')
    plus_context = dict()

    defget_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        if self.plus_context:
            context['success'] = self.plus_context['pass_to_view_just_after_save_successful']
        return context

    defform_valid(self, form, **kwargs):
        self.object.save()
        self.plus_context['pass_to_view_just_after_save_successful'] = 'Save successful!'returnsuper(SomeUpdateView, self).form_valid(form)

in template something like:

{% if success %}
<p>{{ success }}</p>
{% endif %}

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