Question

I have a Django model and from.

class Settings(models.Model):
    field_1 = models.BooleanField()
    field_2 = models.CharField(max_length = 255)

and the form

class SiteSettingsForm(forms.ModelForm):
    class Meta:
        model = SiteSettings

I have an HTML form, and when the checkbox for the Boolean field_1 is not checked, then the 2nd field (field_2) is disabled.

The problem is that, if I try and save the form, it says that there is an error, because field_2 is empty.

I want that, if the field_2 is not disabled and is not empty, to get the error but if field_2 is disabled, I want the form to take the value from the database.

I have tried this:

class SettingsForm(forms.ModelForm):
    class Meta:
        model = Settings

    def __init__(self, *args, **kwargs):
        super(SettingsForm, self).__init__(*args, **kwargs)

    def clean(self):
        field_1 = self.data.get('field_1','')
        if not field_1:   # field_2 is disabled 
            self.data['field_2'] = self.instance.field_2 # so get from db
        super(SettingsForm, self).clean()
        return self.cleaned_data

The problem is that I get an error:

This QueryDict instance is immutable

Answer 1

Change your form for it:

class SettingsForm(forms.ModelForm):
    class Meta:
        model = Settings

    def __init__(self, *args, **kwargs):
        super(SettingsForm, self).__init__(*args, **kwargs)

    def clean(self):
        cleaned_data = super(SettingsForm, self).clean()
        field_1 = cleaned_data.get('field_1','')
        if not field_1:   # field_2 is disabled 
            cleaned_data['field_2'] = self.instance.field_2 # so get from db
        self.cleaned_data = cleaned_data
        return self.cleaned_data