I recently had a use case where I needed to have a single form that could act as either a create or update form. The tricky part was that I wouldn’t know which one was necessary until the data was submitted by the user.
To solve this, I started with Django’s generic UpdateView and overwrote the get_object method so that it would either get the existing record or create a new one (using get_or_create) based on the data being submitted. In my case (and the example below), I had two values that determined whether a new record was necessary or if an existing one should be used.
The underlying ModelForm didn’t require any modification (you could even just use Django’s automatically generated ModelForm by specifying the model in your view).
Here’s the code: