How to create a form object from 2 different model objects in Django?

Question

I have 2 objects, both from different Model classes, and want to show a form containing some fields from each one. How can I do this?

Answer 1

I've never tried this but you could have two ModelForm classes defined in your code and then make a new plain Form class that in its __init__ created a copy of each ModelForm and copied the fields into itself.

Something like:

class DualForm(forms.Form):
    def __init__(self, *args, **kwargs):
        model1 = Model1Form(**kwargs)
        model2 = Model2Form(**kwargs)

        for f in model1.fields:
            self.fields[f] = model1.fields[f]

        for f in model2.fields:
            self.fields[f] = model2.fields[f]

class Model1Form(forms.ModelForm):
    ... your model form...

class Model2Form(forms.ModelForm):
    ... your other model form...

I can't see why it wouldn't work.

Just make sure you pass data arguments through to the ModelForms and trap and bubble exceptions out... I'm also not sure what would happen if you have conflicting field names. That could be troublesome...

Answer 2

The way I do it is by creating two ModelForm classes that use the fields Meta attribute to specify which subset of fields to use to display in the form. I display both forms in the template, and handle them in the view.

Answer 3

Just create 2 separate forms, the problem with with the approach of the guy above is that you would lose .save(). Forms are really meant to represent 1 single set of data, the data for each of yours models is really a separate set of data. This is why forms doesn't include the tag when the render.