Django Models

Django Models are Python classes that define the structure of your database tables. Each of the model represents a sql table, and each attribute in the model represents a database field. Django’s ORM (Object-Relational Mapper) allows you to interact with the database using Python code instead of writing SQL queries.

Why Use Django Models?

• Create database tables using Python classes
• Perform CRUD operations easily
• Manage relationships between tables
• Automatically generate database schemas
• Work with databases without writing SQL

Creating a Model

Open the models.py file and define your model:

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200)
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title

Common Model Fields

from django.db import models

class Employee(models.Model):
    name = models.CharField(max_length=100)
    email = models.EmailField()
    age = models.IntegerField()
    salary = models.DecimalField(max_digits=10, decimal_places=2)
    is_active = models.BooleanField(default=True)
    joined_date = models.DateField()

Frequently Used Fields

Field Type	Description
CharField	Stores short text
TextField	Stores large text
IntegerField	Stores integers
FloatField	Stores decimal numbers
DecimalField	Stores precise decimal values
BooleanField	Stores True/False values
DateField	Stores dates
DateTimeField	Stores date and time
EmailField	Stores email addresses
ImageField	Stores image files
FileField	Stores uploaded files

Register the App

Add the app to INSTALLED_APPS in settings.py:

INSTALLED_APPS = [
    'blog',
]

Create Migrations

Generate migration files:

python manage.py makemigrations

Apply migrations to the database:

python manage.py migrate

Create Records

from blog.models import Post

Post.objects.create(
    title="My First Post",
    content="Welcome to Django Models"
)

Retrieve Records

posts = Post.objects.all()

for post in posts:
    print(post.title)

Update Records

post = Post.objects.get(id=1)
post.title = "Updated Title"
post.save()

Delete Records

post = Post.objects.get(id=1)
post.delete()

Model Relationships

ForeignKey (One-to-Many)

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

class Post(models.Model):
    title = models.CharField(max_length=200)
    category = models.ForeignKey(
        Category,
        on_delete=models.CASCADE
    )

ManyToManyField

class Tag(models.Model):
    name = models.CharField(max_length=50)

class Post(models.Model):
    title = models.CharField(max_length=200)
    tags = models.ManyToManyField(Tag)

OneToOneField

class UserProfile(models.Model):
    user = models.OneToOneField(
        User,
        on_delete=models.CASCADE
    )
    bio = models.TextField()

Meta Class

Use the Meta class to customize model behavior:

class Post(models.Model):
    title = models.CharField(max_length=200)

    class Meta:
        ordering = ['-id']
        verbose_name = "Post"
        verbose_name_plural = "Posts"

Benefits of Django Models

• Database abstraction through ORM
• Easy CRUD operations
• Automatic migrations
• Relationship management
• Database-independent development
• Secure and maintainable code