Fundamentals

Fundamentals Questions

Q1.What is the difference between a list and a tuple in Python?+

Lists are mutable (can be modified after creation), tuples are immutable. Tuples are hashable and can be used as dictionary keys. Tuples are slightly faster due to immutability. Use tuples for fixed collections (coordinates, database rows) and lists for collections that change.

Q2.Explain Python decorators with an example.+

Decorators are functions that modify other functions' behavior. They take a function as input and return a modified function. Django uses decorators extensively: @login_required protects views, @api_view marks DRF views, @cached_property caches computed properties. Custom decorators wrap functions with additional logic like logging or permission checks.

Q3.What are Python generators and when should you use them?+

Generators are functions that yield values one at a time instead of returning a complete list. They use memory efficiently for large datasets. In Django, use generators when processing large querysets — Django's iterator() method uses generators to avoid loading all objects into memory at once.

Q4.Explain the difference between *args and **kwargs.+

*args collects positional arguments into a tuple. **kwargs collects keyword arguments into a dictionary. Django uses **kwargs extensively in function signatures — for example, Model.objects.filter(**kwargs) accepts any number of field lookups. This pattern enables flexible, reusable functions.

Q5.What is the GIL in Python and how does it affect Django?+

The Global Interpreter Lock (GIL) prevents multiple threads from executing Python code simultaneously. This affects CPU-bound Django tasks. For I/O-bound operations (database queries, API calls), threading works fine. For CPU-heavy work, use Celery with multiple worker processes or asyncio.

Django Framework

Django Framework Questions

Q6.Explain Django's MTV architecture.+

Model: defines data structure and database interactions using ORM. Template: handles presentation with Django template language (HTML with template tags). View: contains business logic, processes requests, queries models, and returns responses. URLs map request paths to views. This separation keeps code organized and testable.

Q7.What is the difference between select_related and prefetch_related?+

select_related uses SQL JOINs for ForeignKey and OneToOne relationships — one query gets related objects. prefetch_related makes separate queries and joins in Python — used for ManyToMany and reverse ForeignKey. Using neither causes N+1 query problems: 1 query for the main objects + N queries for each related object.

Q8.How does Django middleware work?+

Middleware processes requests and responses globally. Each middleware has process_request (before view), process_view (before view function), process_response (after view), and process_exception methods. Order matters — SecurityMiddleware, SessionMiddleware, and AuthenticationMiddleware must run in specific order. Custom middleware handles logging, rate limiting, or request transformation.

Q9.Explain Django signals and when to use them.+

Signals allow decoupled components to communicate. pre_save and post_save fire before/after model.save(). post_delete fires after deletion. Use signals for side effects: sending welcome emails after user creation, updating caches after model changes, or logging audit trails. Avoid overusing signals — they make code harder to follow.

Q10.What is Django's QuerySet and how is it lazy?+

A QuerySet represents a database query. It is lazy — no SQL executes until you iterate, slice, or call methods like list(), count(), or exists(). This allows chaining filters (Model.objects.filter().exclude().order_by()) without hitting the database until the final evaluation. Understanding laziness prevents unnecessary queries.

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Project / Practical

Project / Practical Questions

Q11.How would you build a REST API with authentication in Django?+

Install Django REST Framework. Create serializers for models, viewsets with ModelViewSet, and register with a router. For auth, use djangorestframework-simplejwt — add token obtain/refresh endpoints, protect views with IsAuthenticated permission. Use throttle classes for rate limiting and pagination classes for large responses.

Q12.How do you handle database migrations when working in a team?+

Each developer creates migrations on their branch. Merge conflicts in migrations are resolved by running makemigrations --merge. Use squashmigrations periodically to reduce migration count. Never edit applied migrations — create new ones instead. In CI/CD, run migrate as part of deployment.

Q13.Describe how you would implement caching in a Django application.+

Use Django's cache framework with Redis backend. Cache expensive querysets with cache.get/set or @cache_page decorator for views. Use template fragment caching for reusable components. Invalidate cache on model save using signals. For per-user caching, use vary_on_headers or cache keys with user IDs.

Problem Solving

Problem Solving Questions

Q16.How would you handle file uploads for a large file processing system in Django?+

Use chunked uploads with Django's UploadHandler or a library like django-chunked-upload. Store files on S3 using django-storages. Process large files asynchronously with Celery tasks. Add progress tracking using WebSocket or polling. Validate file types server-side and set appropriate MEDIA_ROOT permissions.

Q17.How would you design a multi-tenant Django application?+

Three approaches: schema-based (separate database schema per tenant using django-tenants), shared schema with tenant_id foreign key on every model, or separate databases. Shared schema is simplest — add a TenantMiddleware that sets the current tenant from subdomain or header, and filter all querysets by tenant_id using custom managers.

Frequently Asked Questions

Common Questions

What topics are covered in Python Django interviews?+

Interviews cover Python OOP, Django MTV architecture, ORM queries, REST framework, authentication, middleware, and deployment. Senior roles add performance optimization, caching, and system design.

Are Python interviews harder than PHP interviews?+

Slightly. Python interviews often include DSA questions alongside framework knowledge. Django-specific questions are comparable to Laravel. Companies hiring Python developers may also test data structure knowledge more rigorously.

Does CodingClave prepare students for Django interviews?+

Yes. The 6-month Python Django program at CodingClave in Lucknow includes mock interviews covering Django theory, coding challenges, and behavioral rounds.

Should I learn Django REST Framework for interviews?+

Yes. Most Django job roles require API development. DRF questions — serializers, viewsets, authentication — are standard in interviews. Our 45-day and 6-month programs at CodingClave cover DRF thoroughly.

What salary can I expect after clearing a Django interview?+

Freshers earn ₹3-7 LPA. In Lucknow, ₹3.5-6 LPA. Demonstrating DRF knowledge and deployed projects can push offers higher.

How important is DSA for Django developer interviews?+

Important at product companies and startups. Service companies focus more on Django knowledge. Prepare basic DSA (arrays, strings, hash maps) alongside Django concepts for the best results.

Can I use Python Django knowledge for data science interviews?+

Python skills transfer directly. Django knowledge helps in roles that require building web interfaces for data products. However, data science interviews focus more on statistics, ML, and SQL.

How should I prepare for a Django interview in 2 weeks?+

Review these 15 questions, build one end-to-end Django project with DRF, practice explaining your code, and review Python OOP concepts. Mock interviews at CodingClave in Lucknow accelerate preparation.

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Python Django Interview Questions and Answers 2026

Top 15 Python Django interview questions with answers for freshers. Prepare for Django developer roles in Lucknow and across India.