Django Interview Questions

1. What is Django and what problems does it solve as a web framework?

2. What is the difference between Django and Flask?

3. What is the MTV (Model-Template-View) architecture in Django?

4. What is the Django ORM and how does it map models to database tables?

5. What are Django migrations and how do makemigrations and migrate work?

6. What is the difference between a Django project and a Django app?

7. How does URL routing work in Django with urls.py?

8. What is the difference between a function-based view and a class-based view in Django?

9. What are Django templates and how does the template language work?

10. What is the Django request/response cycle and how does middleware fit in?

11. What is a QuerySet in Django and how is lazy evaluation used?

12. What is the N+1 query problem in Django and how do select_related and prefetch_related help?

13. How do Django model relationships work (ForeignKey, ManyToMany, OneToOne)?

14. What are Django model managers and how do you write a custom manager?

15. How does form handling and validation work in Django?

16. What is the difference between Django ModelForm and a plain Form?

17. How does Django's authentication system work?

18. How does Django handle sessions and cookies?

19. What is CSRF protection in Django and how does it work?

20. How does the Django admin site work and how do you customize it?

21. What is Django REST Framework and how do serializers work?

22. What is the difference between authentication and permissions in Django REST Framework?

23. How does caching work in Django and what backends are available?

24. How do you handle static and media files in Django?

25. What are Django signals and when should you use them?

26. How does Django handle database transactions and atomic operations?

27. What is the difference between Django's null and blank field options?

28. How do you optimize the performance of a Django application?

29. How does Django handle asynchronous views and ASGI?

30. What are Django's built-in security protections against common web vulnerabilities?

31. How do you use select_for_update() in Django to prevent race conditions?

32. How do you run zero-downtime schema migrations in Django?

33. How do you squash Django migrations and resolve migration conflicts on a team?

34. Why do you need transaction.on_commit() when dispatching background tasks in Django?

35. How do nested transaction.atomic() blocks and savepoints behave in Django?

36. How do you build chainable, reusable query logic with custom QuerySet classes in Django?

37. When would you use Subquery and OuterRef instead of prefetch_related in Django?

38. How do you write custom Django middleware and why does MIDDLEWARE ordering matter?

39. How do you handle cache invalidation and cache stampedes in a Django application?

40. How do you safely access the Django ORM from async views without blocking the event loop?

41. How does Django manage database connections, and how do CONN_MAX_AGE and a connection pooler interact?

42. How do you structure Django settings and manage secrets safely across environments?

43. What is the difference between Django's TestCase and TransactionTestCase, and how do you keep a test suite fast and isolated?

44. How do you configure logging and error reporting in a production Django service?

45. How do you choose and tune application server workers when deploying Django with Gunicorn or uWSGI?

46. How do you make background tasks reliable in a Django and Celery system?

47. How do you route queries across multiple databases and read replicas in Django?

48. How do you process very large tables in Django without exhausting memory or locking the database?

49. Why should you set AUTH_USER_MODEL at the start of a project, and how do you extend the user model later?

50. How do you handle user file uploads safely in Django, including validation, storage backends and serving?

51. How do you keep a Django REST Framework API stable under load with pagination, filtering and throttling?

52. How do you decide which database indexes and constraints a Django model needs, and how do you verify them?

53. When do you need a Prefetch() object rather than a plain prefetch_related, and what breaks nested prefetching?

54. What do only() and defer() actually do, and how can they make a page slower?

55. How does Model.save() decide between INSERT and UPDATE, and how do you avoid lost updates under concurrency?

56. How do you write a safe RunPython data migration on a large table?

57. What happens during Django's app registry startup, and why does signal registration belong in AppConfig.ready()?

58. How does .values() change the GROUP BY of an annotated queryset, and why do aggregates over joins double-count?

59. How do content types and GenericForeignKey work, and what do you give up by using them?

60. How does Django handle time zones with USE_TZ, and why do daily reports come out wrong?

61. A Django endpoint is slow in production but fast locally. How do you diagnose it?