Docker Containerization for Django Apps

Learn how to containerize Django applications using Docker for consistent deployments.

## Advanced Django Techniques

### Custom Model Managers
```python
class PublishedManager(models.Manager):
def get_queryset(self):
return super().get_queryset().filter(status='published')

class Post(models.Model):
title = models.CharField(max_length=200)
status = models.CharField(max_length=20, choices=STATUS_CHOICES)

objects = models.Manager() # Default manager
published = PublishedManager() # Custom manager
```

### Django Signals for Automation
```python
from django.db.models.signals import post_save
from django.dispatch import receiver

@receiver(post_save, sender=User)
def create_user_profile(sender, instance, created, **kwargs):
if created:
UserProfile.objects.create(user=instance)
```

### Performance Optimization
- Use select_related() and prefetch_related() for efficient queries
- Implement database indexing for frequently queried fields
- Use Django's caching framework for expensive operations
- Optimize templates with template fragment caching

### Security Best Practices
- Always validate and sanitize user input
- Use Django's built-in CSRF protection
- Implement proper authentication and authorization
- Keep Django and dependencies updated