Pre-populate an inline FormSet?

Question

I\'m working on an attendance entry form for a band. My idea is to have a section of the form to enter event information for a performance or rehearsal. Here\'s the model

Answer 1

Using django 1.7 we ran into some issues creating an inline form with additional context baked into the model (not just an instance of the model to be passed in).

I came up with a different solution for injecting data into the ModelForm being passed in to the form set. Because in python you can dynamically create classes, instead of trying to pass in data directly through the form's constructor, the class can be built by a method with whatever parameters you want passed in. Then when the class is instantiated it has access to the method's parameters.

def build_my_model_form(extra_data):
    return class MyModelForm(forms.ModelForm):
        def __init__(self, *args, **kwargs):
            super(MyModelForm, self).__init__(args, kwargs)
            # perform any setup requiring extra_data here

        class Meta:
            model = MyModel
            # define widgets here

Then the call to the inline formset factory would look like this:

inlineformset_factory(ParentModel, 
                      MyModel, 
                      form=build_my_model_form(extra_data))