[ Django modelling - using the right relationships ]

I want a model 'Model' to have a set (zero or more) of 'Attribute's. It should be able to access these 'Attribute's. A single 'Attribute' has exactly ONE 'Model'.

A 'Model' has zero or more 'Objects'. It should be able to access these 'Object's. A single 'Object' has exactly ONE 'Model'. An 'Object' will inherit all the 'Attribute's of it's 'Model'.

I'm not sure how to create these models in Django.

Here is what I have so far:

class Model(models.Model):
    #

class Attribute(models.Model):
    model = models.ForeignKey(Model)

class Object(models.Model):
    model = models.ForeignKey(Model)

UPDATE

When I try to make an 'Object' object, I get this error:

column myproject_object.model_id does not exist

Similarly, if I try to make a 'Model' object. I get this error:

null value in column "attributes_id" violates not-null constraint

Answer 1

This relation is called Many-to-many relationship and Django has implemented it in its ORM.

 class Child(models.Model):
     # [...]

 class Parent(models.Model):
     children = models.ManyToManyField(Model)

You can access in this way

 parent = Parent()
 parent.save()
 parent.children.all()

Django create automatically the relation in database, I highly recommend you to read the Django documentation about Many-to-many relation.