Python – django abstract models versus regular inheritance

djangodjango-modelspython

Besides the syntax, what's the difference between using a django abstract model and using plain Python inheritance with django models? Pros and cons?

UPDATE: I think my question was misunderstood and I received responses for the difference between an abstract model and a class that inherits from django.db.models.Model. I actually want to know the difference between a model class that inherits from a django abstract class (Meta: abstract = True) and a plain Python class that inherits from say, 'object' (and not models.Model).

Here is an example:

class User(object):
   first_name = models.CharField(..

   def get_username(self):
       return self.username

class User(models.Model):
   first_name = models.CharField(...

   def get_username(self):
       return self.username

   class Meta:
       abstract = True

class Employee(User):
   title = models.CharField(...

Best Solution

I actually want to know the difference between a model class that inherits from a django abstract class (Meta: abstract = True) and a plain Python class that inherits from say, 'object' (and not models.Model).

Django will only generate tables for subclasses of models.Model, so the former...

class User(models.Model):
   first_name = models.CharField(max_length=255)

   def get_username(self):
       return self.username

   class Meta:
       abstract = True

class Employee(User):
   title = models.CharField(max_length=255)

...will cause a single table to be generated, along the lines of...

CREATE TABLE myapp_employee
(
    id         INT          NOT NULL AUTO_INCREMENT,
    first_name VARCHAR(255) NOT NULL,
    title      VARCHAR(255) NOT NULL,
    PRIMARY KEY (id)
);

...whereas the latter...

class User(object):
   first_name = models.CharField(max_length=255)

   def get_username(self):
       return self.username

class Employee(User):
   title = models.CharField(max_length=255)

...won't cause any tables to be generated.

You could use multiple inheritance to do something like this...

class User(object):
   first_name = models.CharField(max_length=255)

   def get_username(self):
       return self.username

class Employee(User, models.Model):
   title = models.CharField(max_length=255)

...which would create a table, but it will ignore the fields defined in the User class, so you'll end up with a table like this...

CREATE TABLE myapp_employee
(
    id         INT          NOT NULL AUTO_INCREMENT,
    title      VARCHAR(255) NOT NULL,
    PRIMARY KEY (id)
);
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