10 Common Django Mistakes and How to Avoid Them

Django is an amazing web framework that helps developers build robust web applications quickly. However, even experienced developers can run into problems if they're not careful. In this blog, we'll go through 10 common mistakes made while working with Django and how to avoid them.

1. Not Using Virtual Environments

Skipping virtual environments can lead to dependency conflicts when working on multiple projects. Each project might need a different version of a package, and without isolation, this can break things.

How to Avoid It: Always create a virtual environment for your project:

python -m venv env
source env/bin/activate  # On Windows: env\Scripts\activate

2. Hardcoding Sensitive Information

Storing database credentials, API keys, or other sensitive information directly in your settings file is risky. If your code ends up in a public repository, these details could be exposed.

How to Avoid It: Use environment variables or a library like python-decouple to manage sensitive information.

Example with environment variables:

import os
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('DB_NAME'),
        'USER': os.getenv('DB_USER'),
        'PASSWORD': os.getenv('DB_PASSWORD'),
    }
}

3. Ignoring Database Indexing

Django models make it easy to work with databases, but if you forget to optimize queries, your app can slow down as your data grows.

How to Avoid It: Add indexes for fields that are frequently queried or filtered. For example:

from django.db import models

class Product(models.Model):
    name = models.CharField(max_length=255, db_index=True)

4. Overloading Models with Business Logic

Django models are meant to represent your database schema, not act as the primary location for business logic. Overloading models can make your code hard to maintain.

How to Avoid It: Keep your models focused on database interactions. Use services or utility modules for complex business logic.

5. Not Using Migrations Properly

Skipping migrations or editing them manually can lead to database inconsistencies.

How to Avoid It: Always run makemigrations and migrate after changing your models. Don’t edit migration files unless you absolutely know what you’re doing.

6. Ignoring Query Optimization

Fetching too much data or using unoptimized queries can hurt performance, especially when working with related models.

How to Avoid It: Use select_related and prefetch_related when querying related models. For example:

# Inefficient
books = Book.objects.all()
for book in books:
    print(book.author.name)
# Optimized
books = Book.objects.select_related('author')
for book in books:
    print(book.author.name)

7. Skipping Tests

Neglecting tests can make it hard to catch bugs or ensure your application behaves as expected after changes.

How to Avoid It: Write tests for your models, views, and forms. Use Django’s built-in testing framework to simplify the process.

8. Using Debug Mode in Production

Leaving DEBUG = True in production can expose sensitive information if errors occur.

How to Avoid It: Always set DEBUG = False in production and configure logging to capture errors.

9. Not Handling Static and Media Files Properly

Mismanaging static and media files can lead to broken stylesheets, images, or uploads in production.

How to Avoid It: Use Django’s collectstatic command and configure a storage backend (e.g., AWS S3) for production.

10. Reinventing the Wheel

Writing custom solutions for common problems, like authentication or file uploads, can waste time and lead to bugs.

How to Avoid It: Leverage Django’s built-in features and third-party packages whenever possible. For example:

Use django.contrib.auth for authentication.
Use django-storages for file storage.

Conclusion

Mistakes happen, but knowing what to watch out for can save you time and effort. By avoiding these common pitfalls, you can build more robust and maintainable Django applications.