Django model - interface design to avoid need of passing object in CHILD class calling method defined in PARENT class

I am using django 2.0.8 and Python 3.5. I have written a base class which encapsulates behavior in a base class.

When using the interface in the child class, I find that I have to pass the object of the child class to the parent - which is not only ugly, is error prone.

I do not want to use composition (instead of an interface), because AFAIK fields in django models are saved to the DB - that aside, I prefer the sub classing approach, since all the functionality can remain in the base class.

Is there any way I can (in the parent class), find/obtain the instance (or at least the name of the class and it's id) that invoked the method call?

Here is my code:

class Likeable(models.Model):
likes = GenericRelation(Like)


def action_is_permissible(self, actionable_object, actor):
ct = ContentType.objects.get_for_model(actionable_object)
object_id = actionable_object.id
found_objects = Like.objects.filter(content_type=ct, object_id=object_id, liker=actor)

return ((len(found_objects) == 0), ct, object_id, found_objects)


def add_like(self, actionable_object, actor):

can_add, ct, object_id, found_objects = self.action_is_permissible(actionable_object, actor)

if can_add:
like = self.likes.create(content_type=ct, object_id=object_id, liker=actor)
else:
# do nothing
return


class Meta:
abstract = True


class Foo(Likeable):
name = models.CharField(max_length=255,default='')
objects = models.Manager()


foo = Foo.objects.get(id=1)
p = User.objects.get(id=1)

foo.add_like(foo, p) # <- nasty API calling convention


1 Answer
1

You can access it using self.
self refers to the object which is calling.

self

self

Ref: What is the purpose of self?

EDIT (code changes):

class Likeable(models.Model):
def add_like(self, actor):
# update `actionable_object` to `self`

foo.add_like(p)


foo.add_like(self, p)

self

add_like

self

self

Likeable

Likeable

Likeable

The method is implemented in the subclass

self

foo

self.id

id

foo

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