12 Advanced Django Interview Questions for Experienced Developers
When interviewing for a senior Django role, you can expect questions that dive deep into performance, scalability, and advanced features of Django. Here are some key questions that often come up:
- How do you optimize Django ORM queries and profile performance?
Optimizing the ORM for complex queries is crucial in Django applications. Understanding select_related, prefetch_related, and query profiling tools can make a big difference.
2. When are Django signals unsuitable, and how can you disable them selectively?
While signals are useful for decoupling, they can lead to unexpected behaviors in complex apps. Knowing when and how to disable them is essential for maintaining control.
3. Explain atomic() and savepoints in Django transactions.
Using atomic() ensures data integrity in multi-step operations, while savepoints allow finer control within a transaction.
4. How would you implement role-based access control in Django?
RBAC offers more granular control over permissions. Understanding how to implement it beyond Django’s built-in groups and permissions is key.
5. Describe select_related vs prefetch_related with examples.
Both methods optimize query performance, but knowing when to use each can significantly impact efficiency.
6. How do you create conditional custom middleware in Django?
Middleware is powerful for request/response modifications. Customizing it conditionally helps target specific scenarios.
7. How can you implement real-time notifications in Django?
Real-time functionality can be added via WebSockets, Django Channels, or Celery, enabling notifications and live data updates.
8. What’s the difference between @cached_property and @property?
@cached_property stores the result after the first access, optimizing repeated calls, while @property recalculates each time.
9. How would you set up and manage multi-database support in Django?
Multi-database setups allow distribution of data, but it requires careful management to avoid consistency issues.
10. How do you handle modifying a migration already applied in production?
Modifying migrations in production requires caution. Understanding rollback and re-application strategies is critical.
11. How would you implement SSO in Django using OAuth2 or SAML?
Implementing SSO with third-party providers enhances security and user experience. Configuring OAuth2/SAML requires backend adjustments.
12. How do you test asynchronous tasks (e.g., Celery) in Django?
Testing async tasks involves handling retries, failures, and efficient test setup for quicker results in the test environment.
These questions target the nuances of Django development and reflect the skills required to manage and scale Django applications effectively.
