Django Proxy Model Inheritance

This is our twenty fourth tutorial in Django, in this tutorial we are going to learn about Django Proxy Model Inheritance, in the two previous tutorials of Model Inheritance, we have learned about two types of Model Inheritance in Django. you can read the articles in the below links.

Django Model Inheritance

1: Django Abstract Based Model Inheritance

2: Django Multi Table Model Inheritance

Flask Web Development Tutorials

1: Flask CRUD Application with SQLAlchemy

2: Flask Creating News Web Application

3: Flask Creating REST API with Marshmallow

What is Django Model Inheritance ?

Model inheritance in Django works almost identically to the way normal class inheritance

works in Python, but with a difference that in Django Model Inheritance you need to

extends from django.db.models.Model.

What is Django Proxy Model Inheritance ?

Proxy model is a type of Django Model Inheritance, which you can extends from the base

class and you can add your own properties except fields. You can create, delete and

update instances of the proxy model and all the data will be saved as if you were using

the original (non-proxied) model. The difference is that you can change things like

the default model ordering or the default manager in the proxy, without having to

alter the original. Proxy models are declared like normal models. You tell Django

that it’s a proxy model by setting the proxy attribute of the Meta class to True.

The usage of the Proxy Model is overriding the main functionality of the existing model.

So now we need to create a New Project in Django, also for django installation

and creating New Project you can read this article Django Introduction & Installation.

but you can use this command for creating of the New Project.

django-admin startproject MyProject

1	django-admin startproject MyProject

So after doing this, let’s create our Django App, i have already talked about Django

App in one of my articles, you can check this Django Apps & URL Routing.

python manage.py startapp MyApp

1	python manage.py startapp MyApp

After creation of the App, you need to add the created App in your settings.py file

INSTALLED_APP section.

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'MyApp',
]

INSTALLED_APPS = [

'django.contrib.admin',

'django.contrib.auth',

'django.contrib.contenttypes',

'django.contrib.sessions',

'django.contrib.messages',

'django.contrib.staticfiles',

'MyApp',

]

Now open your models.py in your MyApp App, and add your models.

from django.db import models


# Create your models here.

class Person(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)

class MyPerson(Person):
    class Meta:
        proxy = True

    def fullName(self):

        return self.first_name + " " + self.last_name

from django.db import models

# Create your models here.

class Person(models.Model):

first_name = models.CharField(max_length=30)

last_name = models.CharField(max_length=30)

class MyPerson(Person):

class Meta:

proxy = True

def fullName(self):

return self.first_name + " " + self.last_name

The MyPerson class operates on the same database table as its parent Person class.

In particular, any new instances of Person will also be accessible through MyPerson,

and vice-versa:

After creating of the models, we need to migrate our project, first you need to do

migrations and after that migrate.

python manage.py makemigrations

1	python manage.py makemigrations

You can see that Django created two database models for us.

Migrations for 'MyApp':
  MyApp\migrations\0003_myperson_person.py
    - Create model Person
    - Create proxy model MyPerson

Migrations for 'MyApp':

MyApp\migrations\0003_myperson_person.py

- Create model Person

- Create proxy model MyPerson

Now you need to migrate.

python manage.py migrate

1	python manage.py migrate

This is the output in the terminal.

Operations to perform:
  Apply all migrations: MyApp, admin, auth, contenttypes, sessions
Running migrations:
  Applying MyApp.0003_myperson_person... OK

Operations to perform:

Apply all migrations: MyApp, admin, auth, contenttypes, sessions

Running migrations:

Applying MyApp.0003_myperson_person... OK

Now let’s just add a data using django shell, first you need to open django shell and add the data.

python manage.py shell

1	python manage.py shell

And add the data

In [1]: from MyApp.models import Person, MyPerson

In [2]: p = Person(first_name = "Codeloop", last_name = "org")

In [3]: p.save()

In [1]: from MyApp.models import Person, MyPerson

In [2]: p = Person(first_name = "Codeloop", last_name = "org")

In [3]: p.save()

After adding the data, now we can access the first_name and last_name through

the fullName() method of MyPerson class that we have our proxy model.

In [7]: myperson = MyPerson.objects.all()[0]

In [8]: myperson.fullName()
Out[8]: 'Codeloop org'

In [7]: myperson = MyPerson.objects.all()[0]

In [8]: myperson.fullName()

Out[8]: 'Codeloop org'

You can see that first we have got the data from the MyPerson class and after that

we have printed the fullName() method.

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