Django Forms
************

.. highlight:: python

Arguments
=========

``views.py``::

  def get_form_kwargs(self):
      kwargs = super().get_form_kwargs()
      kwargs.update({"contact": self._contact()})
      return kwargs

``forms.py``::

  class InvoiceUpdateForm(RequiredFieldForm):
      def __init__(self, *args, **kwargs):
          self.contact = kwargs.pop("contact")
          super().__init__(*args, **kwargs)

Fields
======

To change the text for a ``ChoiceField``::

  class UserModelMultipleChoiceField(forms.ModelMultipleChoiceField):
      def label_from_instance(self, obj):
          return "{} ({})".format(obj.get_full_name(), obj.username)

  class AppSettingsForm(forms.ModelForm):
      class Meta:
          model = AppSettings
          fields = ("app_superusers", "contact_administrators")
          field_classes = {
              "app_superusers": UserModelMultipleChoiceField,
              "contact_administrators": UserModelMultipleChoiceField,
          }

.. tip:: Example from https://gitlab.com/kb/apps/-/blob/master/apps/forms.py

Hidden
======

To hide a field::

  if not settings.show_method:
      self.fields["methods"].widget = forms.HiddenInput()

Initial
=======

::

  def get_initial(self):
      result = super().get_initial()
      result.update(dict(category_type=self._category_type().pk))
      return result

Label
=====

To change the label::

  self.fields["category"].label = "Category"

Required
========

::

 for name in ("assessor_comments", "result"):
    self.fields[name].required = True

Testing
=======

::

  assert HTTPStatus.FOUND == response.status_code, response.context["form"].errors