[Django] FormViewについて詳しく見てみる

class FormView(TemplateResponseMixin, BaseFormView):
    """A view for displaying a form and rendering a template response."""

class BaseFormView(FormMixin, ProcessFormView):
    """A base view for displaying a form."""

class ProcessFormView(View):
    """Render a form on GET and processes it on POST."""
    def get(self, request, *args, **kwargs):
        """Handle GET requests: instantiate a blank version of the form."""
        return self.render_to_response(self.get_context_data())

    def post(self, request, *args, **kwargs):
        """
        Handle POST requests: instantiate a form instance with the passed
        POST variables and then check if it's valid.
        """
        form = self.get_form()
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

    def put(self, *args, **kwargs):
        return self.post(*args, **kwargs)

class FormMixin(ContextMixin):
    """Provide a way to show and handle a form in a request."""
    initial = {}
    form_class = None
    success_url = None
    prefix = None

    def get_initial(self):
        """Return the initial data to use for forms on this view."""
        return self.initial.copy()

    def get_prefix(self):
        """Return the prefix to use for forms."""
        return self.prefix

    def get_form_class(self):
        """Return the form class to use."""
        return self.form_class

    def get_form(self, form_class=None):
        """Return an instance of the form to be used in this view."""
        if form_class is None:
            form_class = self.get_form_class()
        return form_class(**self.get_form_kwargs())

    def get_form_kwargs(self):
        """Return the keyword arguments for instantiating the form."""
        kwargs = {
            'initial': self.get_initial(),
            'prefix': self.get_prefix(),
        }

        if self.request.method in ('POST', 'PUT'):
            kwargs.update({
                'data': self.request.POST,
                'files': self.request.FILES,
            })
        return kwargs

    def get_success_url(self):
        """Return the URL to redirect to after processing a valid form."""
        if not self.success_url:
            raise ImproperlyConfigured("No URL to redirect to. Provide a success_url.")
        return str(self.success_url)

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

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

    def get_context_data(self, **kwargs):
        """Insert the form into the context dict."""
        if 'form' not in kwargs:
            kwargs['form'] = self.get_form()
        return super().get_context_data(**kwargs)