Using Django ORM to Interact with Databases
🧠 Using Django ORM to Interact with Databases
The Django ORM lets you work with databases using Python objects, rather than writing raw SQL. It handles everything from table creation to complex queries in a clean, high-level API.
🔧 1. Defining Models (Tables)
In Django, each model class represents a table in your database.
Example:
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# models.py
from django.db import models
class Book(models.Model):
title = models.CharField(max_length=200)
author = models.CharField(max_length=100)
published_date = models.DateField()
is_available = models.BooleanField(default=True)
def __str__(self):
return self.title
models.CharField → maps to VARCHAR
models.DateField → maps to DATE
models.BooleanField → maps to BOOLEAN
⚙️ 2. Creating the Table
After defining your model, run these commands to create the actual database tables:
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python manage.py makemigrations
python manage.py migrate
✍️ 3. CRUD Operations Using Django ORM
✅ Create
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book = Book.objects.create(
title="1984",
author="George Orwell",
published_date="1949-06-08"
)
🔍 Read
Get all books:
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books = Book.objects.all()
Filter by author:
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orwell_books = Book.objects.filter(author="George Orwell")
Get a single book:
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book = Book.objects.get(id=1) # Raises error if not found
Get or return None:
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book = Book.objects.filter(id=1).first()
📝 Update
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book = Book.objects.get(id=1)
book.is_available = False
book.save()
❌ Delete
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book = Book.objects.get(id=1)
book.delete()
🔁 4. Advanced Queries
Ordering:
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Book.objects.order_by('published_date') # Ascending
Book.objects.order_by('-published_date') # Descending
Chaining filters:
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Book.objects.filter(author="George Orwell", is_available=True)
Field lookups:
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Book.objects.filter(title__icontains="war") # Case-insensitive search
Book.objects.filter(published_date__year=1949)
📦 5. Using Django Admin (Optional Bonus)
Register your model in admin.py to manage it via Django's built-in admin interface:
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from django.contrib import admin
from .models import Book
admin.site.register(Book)
✅ Summary
Task ORM Command Example
Create Book.objects.create(...)
Read Book.objects.all(), get(), filter()
Update book.save() after modifying a field
Delete book.delete()
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Setting Up PostgreSQL for Full Stack Python Projects
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Introduction to Databases for Full Stack Python Development
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