Alter fields in Django formset using clean

Question

How do you alter fields in each form of a Django formset using the clean method?

class MyInlineFormSet(BaseInlineFormSet):

    def clean(self):
        if self.cleaned_data['inputted'] == self.cleaned_data['answer']:
            self.cleaned_data['is_correct'] = True
        return self.cleaned_data

This isn't working and I've seen people iterate over each form but they only validate and not alter. If I iterate over each form how do I then return the cleaned_data? In other words:

class MyInlineFormSet(BaseInlineFormSet):

    def clean(self):    
        for form in self.forms:
            if form.cleaned_data['inputted'] == form.cleaned_data['answer']:
                form.cleaned_data['is_correct'] = True
        ...?

score 2 · Answer 1 · answered May 17 '18 at 14:20

2

Based on ssomnoremac comment, I used form.instance.field_i_wanted_to_change in the BaseModelFormSet clean method instead of form.cleaned_data['field_i_wanted_to_change'] and it worked. Something like

class MyInlineFormSet(BaseInlineFormSet):

def clean(self):
    for form in self.forms:
        if form.cleaned_data['inputted'] == form.cleaned_data['answer']:
            form.instance.is_correct = True

In my case, I had already called clean_field_i_wanted_to_change, so the order is clean_field > clean @ MyInlineFormSet Django 1.11

answered May 17 '18 at 14:20

Raphael Fernandes

783
8
11

I am facing an exact similar situation. In my formset one of the fields is a boolean with default as `False`. Within the `for form in self.forms:` I am running a check and trying to **change** the boolean's status to `True` but not working. My code goes like this: `if someVar < someValue:` `if form.cleaned_data['myBool'] == False:` `form.instance.myBool = True`. Somehow I am unable to make this work. – Love Putin Not War Apr 27 '22 at 13:24

DavidM · Answer 2 · 2014-03-31T18:56:34.647

0

I believe you are on the right track by iterating through each form and setting the cleaned data (your second example). BaseFormSet has a property called cleaned_data that returns a list of the cleaned data for each form. Is that what you want? E.g.:

return self.cleaned_data

It literally returns:

[form.cleaned_data for form in self.forms]

which should have the correct data (as modified), if I'm reading the code correctly.

If you are only interested in saving the value in your model, I suggest you avoid the clean method and instead override the save methods:

def save_new(self, form, commit=True):
    form.instance.is_correct = ...
    return super(...).save_new(...)

def save_existing(...)

edited Mar 31 '14 at 18:56

answered Mar 31 '14 at 15:43

DavidM

1,417
1
13
16

2

David, thanks. Your answer is right about self.cleaned_data but that still didn't change the field. The problem was cleaned_data is only an accessor not a modifier. What I needed instead: 'form.instance.is_correct = True' form.instance actually modifies the field as explained in the docs [https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#overriding-clean-on-a-modelformset] – ssomnoremac Mar 31 '14 at 17:03
Added to my answer. I'm glad you figured it out and I think this is a useful question, since inline forms need to be handled a bit differently than normal forms. Feel free to submit your own answer if mine doesn't say what you want. – DavidM Mar 31 '14 at 19:00

Alter fields in Django formset using clean

2 Answers2