Code-Memo

Model Inheritance

Types of Model Inheritance

Abstract Base Classes

• Usage: Abstract base classes are used when you only want to define common fields and methods for other models to inherit, without creating database tables for the base class itself.

• Example:

  class CommonInfo(models.Model):
      name = models.CharField(max_length=100)
      age = models.IntegerField()
  
      class Meta:
          abstract = True
  
  class Student(CommonInfo):
      student_id = models.CharField(max_length=10)
  

  • CommonInfo serves as an abstract base class with name and age fields, and Student inherits these fields along with its own student_id field.

Multi-table Inheritance

• Usage: Multi-table inheritance creates a new database table for each child model while keeping a link between them using a one-to-one relationship.

• Example:

  class Place(models.Model):
      name = models.CharField(max_length=100)
      address = models.CharField(max_length=200)
  
  class Restaurant(Place):
      serves_hot_dogs = models.BooleanField(default=False)
  

  • Restaurant inherits all fields from Place and adds its own serves_hot_dogs field, with Django creating a one-to-one link between Place and Restaurant.

Proxy Models

• Usage: Proxy models allow you to create a new Python class that acts as an alias to an existing model, providing a different Python interface to the same database table.

• Example:

  class MyModel(models.Model):
      field1 = models.CharField(max_length=100)
  
  class MyModelProxy(MyModel):
      class Meta:
          proxy = True
  

  • MyModelProxy is a proxy model that behaves like MyModel but can have different methods or customizations without affecting the database schema.