Django ModelForm with extra fields that are not in the model

EDIT 2020 (Django 2 or higher)

In Django 2+ you can add the extra fields like this:

class ProfileForm(forms.ModelForm):        extra_field = forms.ImageField()    class Meta:        model = User        fields = ['username', 'country', 'website', 'biography']

Original answer (Django 1)

It's possible to extend Django ModelForm with extra fields. Imagine you have a custom User model and this ModelForm:

class ProfileForm(forms.ModelForm):    class Meta:        model = User        fields = ['username', 'country', 'website', 'biography']

Now, imagine you want to include an extra field (not present in your User model, lets say an image avatar). Extend your form by doing this:

from django import formsclass AvatarProfileForm(ProfileForm):    profile_avatar = forms.ImageField()    class Meta(ProfileForm.Meta):        fields = ProfileForm.Meta.fields + ('profile_avatar',)

Finally (given that the form has an ImageField), remember to include request.FILES when instantiating the form in your view:

# (view.py)def edit_profile(request):    ...    form = AvatarProfileForm(        request.POST or None,         request.FILES or None,         instance=request.user    )    ...

Hope it helps. Good luck!

EDIT:

I was getting a "can only concatenate tuple (not "list") to tuple" error in AvatarProfileForm.Meta.fields attribute. Changed it to a tuple and it worked.

I had a very similar problem except it looked like I did all the required thing, but I was getting this error when Django was starting:

django.core.exceptions.FieldError: Unknown field(s) (my_new_field) specified for MyModel

This was a silly mistake from me, I accidentally declared my field using a Widget class:

class MyForm(forms.ModelForm):    my_new_field = forms.HiddenInput()

Instead of a Field class:

class MyForm(forms.ModelForm):    my_new_field = forms.CharField(widget=forms.HiddenInput())

Not answering the question at hand here (which is answered well already), but might help others.

First add the field in the form

class CreateForm(forms.ModelForm):extra_field     = forms.CharField(label = 'extra_field', required = False)

Now while cleaning you data, you need to retrive the extra field from self.data NOT self.cleaned_data

Correct:

 self.data.get('extra_field')

Wrong:

 self.cleaned_data.get('extra_field')