Models & ORM in Django

Django Models are the foundation of database management in Django applications.

They work with Django’s ORM (Object Relational Mapper) to interact with databases using Python code instead of SQL.

What is a Django Model?

A Django Model is a Python class that represents a database table.

Each attribute of the model represents a column in the table.

from django.db import models

class Product(models.Model):
    name = models.CharField(max_length=100)
    price = models.IntegerField()

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What is Django ORM?

ORM stands for Object Relational Mapping, which allows developers to interact with databases using Python objects.

It eliminates the need to write complex SQL queries manually.

How ORM Works

Django ORM converts Python code into SQL queries behind the scenes.

This makes database operations faster and easier to manage.

Creating a Model

Models are defined inside the models.py file of a Django app.

class User(models.Model):
    name = models.CharField(max_length=100)
    email = models.EmailField()
    age = models.IntegerField()

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Model Fields

Django provides different field types to define database columns.

CharField - Text data
IntegerField - Numbers
EmailField - Email addresses
DateTimeField - Date and time

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Migrations

Migrations are used to apply model changes to the database.

python manage.py makemigrations
python manage.py migrate

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Creating Records

You can create database records using Django ORM methods.

user = User.objects.create(name='John', email='john@example.com', age=25)

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Retrieving Data

Django ORM provides simple methods to fetch data from the database.

users = User.objects.all()

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Filtering Data

You can filter records using conditions.

User.objects.filter(age=25)

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Getting Single Object

Use get() to retrieve a single record.

User.objects.get(id=1)

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Updating Records

Records can be updated by modifying object attributes and saving them.

user = User.objects.get(id=1)
user.age = 30
user.save()

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Deleting Records

You can delete records using the delete() method.

user = User.objects.get(id=1)
user.delete()

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Model Meta Options

Meta class allows customization of model behavior.

class User(models.Model):
    name = models.CharField(max_length=100)

    class Meta:
        ordering = ['name']

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Relationships in Models

Django supports relationships like One-to-One, One-to-Many, and Many-to-Many.

class Post(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)

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Why ORM is Powerful

ORM improves productivity by removing the need for raw SQL queries.

It also reduces errors and improves code readability.

Common Beginner Mistakes

Beginners often forget to run migrations after changing models.

Another mistake is using inefficient queries instead of ORM methods.

Best Practices

Always define proper field types and use indexes for performance optimization.

Keep models clean and avoid adding business logic directly inside them.

Real-World Importance

Django ORM is widely used in production applications for handling complex database operations.

It powers backend systems for startups, enterprises, and large-scale web platforms.

Summary

Django Models and ORM simplify database interactions using Python code.

Mastering ORM is essential for building efficient Django backend applications.