Question 1

How do I set up fastapi-cache with Redis for my FastAPI app?

Accepted Answer

Install fastapi-cache2 with the redis extra, initialize RedisBackend during FastAPI startup using the lifespan event, and apply the @cache decorator to endpoints. Ensure the Redis client has decode_responses=False to avoid caching issues, as specified in the backend notes.

Question 2

fastapi-cache vs aiocache: which is better for FastAPI?

Accepted Answer

fastapi-cache is tailored for FastAPI with built-in HTTP cache support and seamless decorator integration, while aiocache is a general async caching library. Choose fastapi-cache for tight FastAPI integration and HTTP features, but aiocache for broader async use outside FastAPI.

Question 3

Does fastapi-cache work with async endpoints and functions?

Accepted Answer

Yes, fastapi-cache fully supports async functions, as shown in usage examples where async endpoints are decorated with @cache. It works with async backends like Redis and Memcached, making it suitable for modern async FastAPI applications.

Question 4

How can I cache a Pydantic model response without breaking deserialization?

Accepted Answer

Ensure your endpoint has a return type annotation for the Pydantic model, then use the @cache decorator. The cache uses this annotation to deserialize data correctly; without it, results may be cached as primitive JSON, leading to errors.

Question 5

What happens if I use the in-memory backend in production?

Accepted Answer

The in-memory backend is not recommended for production as it doesn't auto-clean expired keys unless accessed, causing memory leaks over time. It's best for development or testing, with Redis or Memcached preferred for scalability.

Question 6

Can I implement custom cache invalidation with fastapi-cache?

Accepted Answer

fastapi-cache primarily relies on time-based expiration; for custom invalidation, you'd need to manually delete cache keys using backend methods or implement external logic, as the library doesn't provide built-in event-driven invalidation.

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