What does self.instance in Django ModelForm constructor mean and where can I find a documentation about it?
class MyModelForm(ModelForm): def __init__(self, *args, **kwargs): super(MyModelForm, self).__init__(*args, **kwargs) if self.instance: ...
In a ModelForm, self.instance is derived from the
model attribute specified in the Meta class. Your
self in this context is obviously an instance of your subclass of ModelForm, and self.instance is (and will be on saving the form without errors) an instance of the model class you specified, although you have not done so in your example.
Accessing self.instance in
__init__ may not work, though doing so after calling the parent’s
__init__ probably will. Further, I wouldn’t recommend trying to change the instance directly. If you are interested, have a look at the BaseModelForm code on Github. The
instance can also be specified when creating a new form via the
You can find the documentation on django’s website.
Just search the page for every reference to “instance”, and you should find what you need.
# Load up an instance my_poll = Poll.objects.get(id=1) # Declare a ModelForm with the instance my_form = PollForm(request.POST, instance=my_poll) # save() will return the model_form.instance attr which is the same as the model passed in my_form.save() == my_poll == my_form.instance