Django Models

Django offers ORM (Object Relational Mapping) which lets you run SQL queries in a pythonic way.

SQL:

SELECT * FROM Reporter;

Django

Reporter.objects.all()

Why we should use ORM instead of raw SQL queries?
Developers of Django made sure that if we use built-in ORM, we will not become the victims of SQL Injection attacks. Using the raw SQL queries there's a high chance some hackers may do the SQL Injections attacks.

Things to remember:
Say we have this type of Project structure with the below models and the django default migrations have been migrated:

.
├── core
│   ├── __init__.py
│   ├── __pycache__
│   ├── asgi.py
│   ├── models.py
│   ├── settings.py
│   ├── urls.py
│   ├── views.py
│   └── wsgi.py
├── db.sqlite3
└── manage.py

# core.models.py
from django.db import models

class Reporter(models.Model):
    full_name = models.CharField(max_length=70)

    def __str__(self):
        return self.full_name

class Article(models.Model):
    pub_date = models.DateField()
    headline = models.CharField(max_length=200)
    content = models.TextField()
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    def __str__(self):
        return self.headline

1. After making some edits to the core/models.py, run

python3 manage.py makemigrations core
python3 manage.py migrate

We should always specify which app the migrations should be made to.

1. __startswith

>>> Reporter.objects.get(full_name__startswith="Jo")
<Reporter: John Smith>

1. __contains

>>> Reporter.objects.get(full_name__contains='John')
<Reporter: John Smith>

1. Foreign key

>>> r = Reporter.objects.get(id=1)
>>> a = Article(pub_date=date.today(), headline="ORM", content="Hello", reporter=r)

>>> a.reporter
'John Smith'

>>> r.article_set.all()
<QuerySet [<Article: ORM>]>

1. filter(pub_date__year)

>>> date.today().year
2025
>>> Article.objects.filter(pub_date__year=date.today().year)
<QuerySet [<Article: ORM>]>