Examples
Examples

Django Models


What is Django Models

  • Django models are a powerful way to interact with your database in a structured and organized manner.
  • Each model class typically represents a database table, with its attributes defining the fields of the table.
  • In Django, data is represented using objects called models, which correspond to tables in a database.

Using MySQL with Django

  • MySQL is an open-source relational database management system (RDBMS) widely used in web applications due to its performance, reliability, and scalability.
  • Django supports MySQL as a database backend, allowing you to store and manage your application's data.

1. Install MySQL Client for Python

To use MySQL with Django, you need to install the mysqlclient package.

pip install mysqlclient

2 Configure MySQL in settings.py

In your Django project's settings.py, update the DATABASES section like this:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'db_ecommerce',
        'USER': 'root',
        'PASSWORD': '',
        'HOST':'localhost',
        'PORT':'3306',
    }
}

3. Creating a Django Model

After setting up MySQL, you need to create a model inside your myproject/myapp/models.py file.

Example: Defining a Product Model

from django.db import models

class Product(models.Model):
    product_name = models.CharField(max_length=150)
    price = models.FloatField()
    unit = models.CharField(max_length=20)

    class Meta:
        db_table = "tbl_products"

4. Make Migrations

Run python manage.py makemigrations Django creates a migration file that describes the changes made to your models and stores the file in the /migrations/ folder

python manage.py makemigrations myapp
D:\django_projects\myproject>python manage.py makemigrations myapp
Migrations for 'myapp':
  myapp\migrations\0001_initial.py
    - Create model Product

4. Migrate

The migrate command applies the migration files to your actual database( executing the database operations described in your migration files). 

python manage.py migrate
D:\django_projects\myproject>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, myapp, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying auth.0012_alter_user_first_name_max_length... OK
  Applying myapp.0001_initial... OK
  Applying sessions.0001_initial... OK

After migration the database will look like this:

Migrate the DB Structure Db table Structure

Common Field Types

Field Type Description Syntax
AutoField Integer that auto-increments; primary key by default. id = models.AutoField(primary_key=True)
CharField Short text (needs max_length) name = models.CharField(max_length=100)
TextField Long text description = models.TextField()
IntegerField Integer values quantity = models.IntegerField()
DecimalField Decimal numbers (need max_digits, decimal_places) price = models.DecimalField(max_digits=10, decimal_places=2)
BooleanField True/False is_active = models.BooleanField(default=True)
DateTimeField Date and time (auto_now_add for creation) created_at = models.DateTimeField(auto_now_add=True)
DateField Only date birth_date = models.DateField()
ForeignKey One-to-many relation category = models.ForeignKey(Category, on_delete=models.CASCADE)
ManyToManyField Many-to-many relation tags = models.ManyToManyField(Tag)
OneToOneField One-to-one relation profile = models.OneToOneField(Profile, on_delete=models.CASCADE)
ImageField Image upload (needs Pillow) photo = models.ImageField(upload_to='images/')
FileField File upload document = models.FileField(upload_to='docs/')
BigAutoField 64-bit integer that auto-increments; primary key alternative to AutoField. id = models.BigAutoField(primary_key=True)
BigIntegerField Large integers (64-bit). views = models.BigIntegerField()
SmallIntegerField Small range of integer values. rating = models.SmallIntegerField()
PositiveIntegerField Positive integers only (>= 0). stock = models.PositiveIntegerField()
PositiveSmallIntegerField Small positive integers (>= 0). rank = models.PositiveSmallIntegerField()
FloatField Floating-point numbers. rating = models.FloatField()
EmailField CharField that checks for valid email format. email = models.EmailField()
URLField Validates URLs; rendered as a URL input in forms. website = models.URLField()
SlugField Short label for URLs, typically generated from another field (e.g. title). slug = models.SlugField(unique=True)
UUIDField Stores a universally unique identifier (UUID). uid = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
GenericIPAddressField Stores IPv4 or IPv6 addresses. ip_address = models.GenericIPAddressField()
TimeField Stores only time values (no date). start_time = models.TimeField()
DurationField Stores Python timedelta values (e.g., for time intervals). duration = models.DurationField()
BinaryField Stores raw binary data (e.g., for files or binary blobs). filedata = models.BinaryField()
JSONField Stores structured JSON data (Django 3.1+). metadata = models.JSONField()

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