##### edit.pt
<html>
  <body>
    <form method="POST">
      <fieldset tal:replace="structure view/form/as_p" />
      <input type="submit" />
    </form>
  </body>
</html>

##### app.py

[....]

from django.forms import ModelForm

class FooForm(ModelForm):
    class Meta:
        model = Foo

class Edit(grok.View):
    grok.context(Foo)

    _form = None

    def form(self):
	if self._form is not None:
            return self._form

	form = FooForm(instance=self.context)
        self._form = form
        return form

    def update(self):
	if self.request.method != "POST":
            return
	form = FooForm(self.request.form, instance=self.context)
	if form.is_valid():
            form.save()
            return self.redirect(self.url())
	self._form = form