CODEWITHSUNDEEP
pythondjangodjango-modelsdjango-rest-framework
Johnbosco
Johnbosco

Reputation: 73

Django. How to store parent model fields from mixin in child model?

please I have an issue with model relationships in my Django project. For instance I have a model Foo which inherits from a model mixin FooBarMixin which is an abstract class and Bar which is a model but has a OnetoOne relationship with Foo. Basically this is the current implementation.

class Foo(FooBarMixin):
        pass

class FooBarMixin(model.Model):
    bar = model.OneToOneField(Bar, on_delete=CASCADE,             
                     related_name="tracked_%(class)s")
    class Meta:
         abstract = True

class Bar(model.Model):
     pass

Is it possible to store Bar data on the child model Foo without using a OnetoOne relationship ? and if so how do I go about it? Thank you

Upvotes: 2

Views: 281

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476740

Sorry I meant I want the fields in Bar to be visible on the Foo table.

Based on your comment you thus want to fetch fields of the Bar relation in Foo instances.

We could do that by patching the __getattr__ function:

class Foo(FooBarMixin):

    def __getattr__(self, name):
        try:
            return super(Foo, self).__getattr__(name)
        except AttributeError:
            return getattr(self.bar, name)

So in case the attribute can not be fecthed from the Foo instance itself, we fallback on the corresponding self.bar object, and aim to obtain the attribute at that place.

Setting the attribute would require to override the __setattr__ function in a similar way, although I would advice against that, since it will introduce all kinds of side-effects (saving the corresponding .bar object, etc.).

Upvotes: 1

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