django

Signals and save overrides both handle model events, but have different use cases. I override save() for logic intrinsic to the model. Signals decouple logic across apps—I use them when multiple apps need to respond to model changes. Signals can make

URL namespaces prevent name collisions across apps. I set app_name in app-level urls.py and use namespace in include(). Reverse lookups use reverse('namespace:name') or {% url 'namespace:name' %} in templates. This makes URLs maintainable when refacto

Graphene brings GraphQL to Django. I define types mapping to models and create resolvers for queries and mutations. Clients request exactly the data they need, reducing over-fetching. I use DjangoObjectType for automatic schema generation from models.

Aggregation performs database-level calculations efficiently. I use aggregate() for single results across entire queryset (like average or total) and annotate() to add calculated fields to each object. Common aggregates include Count, Sum, Avg, Min, a

DRF permissions control access to API endpoints. I use built-in permissions like IsAuthenticated, IsAdminUser, or IsAuthenticatedOrReadOnly. For custom logic, I create permission classes implementing has_permission() and has_object_permission(). I com

Overriding the save() method allows custom behavior before or after saving. I call super().save() to preserve default behavior. Common use cases include auto-generating slugs, updating related objects, or validating business rules. I use created check

Custom middleware lets me inspect or modify every request and response. I implement both __init__ (called once at startup) and __call__ (for each request). By storing start time in the request, I can measure total processing time including view and te

django-allauth provides ready-made social auth (Google, Facebook, GitHub, etc.). I configure providers in settings with API keys. It handles OAuth flows, token management, and account linking. Users can login with multiple providers. I customize templ

Custom managers encapsulate common query patterns. I create a manager method for each frequently-used filter like published() or active(). By returning self, I can chain manager methods. For more complex queries, I create a custom QuerySet class and u

For queries too complex for the ORM, I use raw SQL. The raw() method returns model instances. I use cursor.execute() for non-model queries. I always use parameterized queries to prevent SQL injection—never string interpolation. For reporting, raw SQL

Window functions perform calculations across rows related to the current row. I use them for running totals, rankings, and moving averages. Django's Window expression with functions like RowNumber, Rank, DenseRank provide SQL window function support.

Extending Django's user model should be done early in projects. I use AbstractBaseUser for full control or AbstractUser to extend the default. Setting AUTH_USER_MODEL points Django to my custom model. I add fields like phone, avatar, or preferences. F