FastAPI

Build a validated FastAPI create endpoint with safe models

Builds a FastAPI POST boundary with separate input/output models, forbidden extra fields, domain mapping, and a 201 response.

Handle an optimistic version conflict with SQLAlchemy

Uses SQLAlchemy version counters and an HTTP precondition to reject stale writes without silently overwriting newer state.

How do dependencies with `yield` manage resource lifetime in FastAPI?

Explains acquisition and cleanup around `yield`, including request and function scopes, streaming, and exception-safe ownership.

How does a request flow through FastAPI and its ASGI stack?

Traces a request from the ASGI server through middleware, routing, dependencies, validation, handler execution, and response completion.

How does FastAPI decide whether a parameter comes from the path, query, header, cookie, body, or a dependency?

Explains FastAPI parameter-source inference and when explicit markers make an HTTP contract clearer.

How does FastAPI resolve and cache dependencies for one request?

Explains dependency graphs, sub-dependencies, request-local caching, failures, and deliberate cache bypass.

Python Backend

Python backend interview preparation grounded in real service development.

A backend-focused Python preparation path covering language semantics, typing, FastAPI, Django, concurrency, data access, testing, security, background work, reliability, and production diagnosis.