ModelForm doesn't support MultiValueDict as initial argument

[Ilya Semenov]

The following code works fine:

class MyForm(forms.Form):
  foo = forms.CharField()

form = MyForm(initial=request.GET) # can be accessed as http://host/view/?foo=default_value

The following code does not fetch the values from request.GET:

class Foo:
  foo = models.CharField(max_length=255)

class MyForm(forms.ModelForm):
  class Meta:
    model = Foo

form = MyForm(Foo(), initial=request.GET) # does nothing

However, the following hack can be used to fetch the values from request.GET:

class Foo:
  foo = models.CharField(max_length=255)

class MyForm(forms.ModelForm):
  class Meta:
    model = Foo

form = MyForm(Foo(), initial=dict(request.GET.items())) # works as expected

Suggested behaviour: initial argument to ModelForm should accept MultiValueDict's, as the base Form implementation does.

[Matt McClanahan]

It's not so much that a MultiValueDict isn't accepted, but that its values will be seen as lists, since a dict.update() doesn't know what a MultiValueDict is.

[Malcolm Tredinnick]

No, I don't think this is worth doing. There's no real use case for not just using a normal dictionary for the "initial" parameter. The example given in the ticket report isn't convincing, as GET data is designed to passed via the "data" parameter, not via "initial".

If somebody has a multi-value structure, they can do type the extra characters to convert it to something that is a dictionary proxy fairly easily, so we shouldn't have to add support for this in Django.