MultiWidget is_hidden is True if subwidgets are dynamically added during its render function

[Meredith Roman]

I have a custom MultiWidget that dynamically adds subwidgets during its render function. I use this widget as part of a form builder that lets a user generate a checklist or radio field with as many options as they need. Because I don't know how many subwidgets the user will need, I am unable to set the subwidgets during form initializaiton.

This is how I add subwidgets during the MultiWidget's render function:

def render(self, name, value, attrs=None):
  if not isinstance(value, list):
    value = self.decompress(value)
  self.widgets = []
  for option in value:
    self.widgets.append(forms.TextInput())
  return super(OptionsWidget, self).render(name, value, attrs) 

This is the way that the MultiWidget is_hidden property is currently set:

@property
def is_hidden(self):
  return all(w.is_hidden for w in self.widgets)

Because I do not have any subwidgets assigned to my widget at form initilaization, and because all() returns True on an empty iterable, is_hidden was set to True for my widget.

I'm currently using this overwritten version of is_hidden for the widget:

@property
def is_hidden(self):
  return False if self.widgets == [] else all(w.is_hidden for w in self.widgets)

[Tim Graham]

I could imagine not every user would want the behavior you desire, and it seems a bit of an edge case. Therefore, it might be better to continue using your own subclass.