Question 1

How to structure a large FastAPI project for scalability?

Accepted Answer

Use a domain-driven approach with modules inside a `src` folder, as recommended in the guide, which separates concerns like routers, schemas, and services per domain to ease maintenance.

Question 2

FastAPI async vs sync: when to use each?

Accepted Answer

Prefer async routes for I/O-bound tasks to avoid blocking the event loop, but use sync routes in a threadpool for blocking I/O, and offload CPU-intensive work to external processes, per the async routes section.

Question 3

How to validate requests with dependencies in FastAPI?

Accepted Answer

Move complex validations like database checks into dependencies, which can be chained and cached, reducing code duplication—examples include checking post existence or user permissions.

Question 4

FastAPI best practices vs official documentation: what's the difference?

Accepted Answer

This guide offers opinionated, production-tested conventions beyond basics, focusing on scalability and maintainability, while official docs provide foundational API references and simpler examples.

Question 5

Best way to handle Pydantic models in FastAPI responses?

Accepted Answer

Create custom base models for consistent serialization, but note that FastAPI validates responses twice, which can impact performance; use `serializable_dict` methods to optimize.

Question 6

How to set up Alembic migrations for FastAPI?

Accepted Answer

Follow naming conventions, make migrations static and reversible with descriptive slugs, and use a file template like `date_slug.py`, as advised in the migrations section.

Question 7

How to write integration tests for async FastAPI apps?

Accepted Answer

Use async test clients like httpx from the start to avoid event loop errors, and structure tests per domain with async fixtures, as shown in the testing setup example.

FastAPI Best Practices

What is FastAPI Best Practices?

Overview

Use Cases

Best For

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Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions