db.models.TextField.formfield() does not behave like CharField.formfield() when null=True

[Ole Laursen]

I have a specific use case where I need null instead of the empty string in the database when some text fields passing through a form are not filled in.

This works fine for CharFields, but I recently discovered that it doesn't for TextFields. For TextFields they always turn out as the empty string.

It looks like CharField has this specific support for setting empty_value = None in .formfield(), but TextField does not:

        if self.null and not connection.features.interprets_empty_strings_as_nulls:
            defaults["empty_value"] = None

I would expect them to behave the same.

[Natalia Bidart]

Hello Ole Laursen, thank you for taking the time to create this ticket. I understand your proposal and in fact I have created a small project that reproduces what you describe.

In order to provide a resolution for this ticket, I have made a lot of research, so I'll share my findings to then explain how I arrived to the final conclusion.

1. The behavior that you describe is exactly as documented ​in this link (this is a table documenting the mapping between model fields and their form fields counterparts when using a ModelForm):

   CharField ------> CharField with max_length set to the model field’s max_length and empty_value set to None if null=True.
   TextField ------> CharField with widget=forms.Textarea
   

   Please note that both CharField and TextField model fields map to a CharField form field, they just have different configuration.

2. The feature that you request (empty_value being automatically set to None for TextField) can be easily achieved by adding this to your model form definition:

   my_text_field = forms.CharField(required=False, empty_value=None, widget=forms.Textarea)
   

3. The empty_value feature for CharField was implemented when solving ticket #4136. I can't see an explicit conversation about supporting (or not) the new parameter for TextField, which makes me think this was just missed in that work (due to the focus in CharField).

Because of all the above, at first I was inclined to accept this ticket, since I agree that this is definitely a useful mechanism to deal with the duality None/empty strings for these fields; and from my investigation there are no duplicate reports nor previous discussion about this. But, OTOH, making this change would mean effectively doing a backward incompatible change to the behavior of TextField when used in a ModelForm, and I don't see a way that we could provide a deprecation path to migrate code that would, at the same time, allow for the deprecation to be "solved" and stop alerting during the whole period of deprecation.

Given the above, I think that the correct resolution for this ticket is wontfix, but if you disagree, I encourage you to propose and discuss this proposal with the community and gain consensus to make this change. To do that, please start a new conversation on the ​Django Forum, where you'll reach a broader audience and receive additional feedback.

I'll close the ticket for now, but if the community agrees with the proposal, please return to this ticket and reference the forum discussion so we can re-open it. For more information, please refer to ​the documented guidelines for requesting features.