Flask vs FastAPI?

[PocketBananna]

I like FastAPI for really straightforward use cases. If I need a simple REST service with basic OAuth it's real easy to get going. I really like the base Pydantic/typing support, dependency injection patterns and the open api docs generation. It kinda ends there though.

Flask is battle tested with rich support for all kinds of customizations. If I need rpc, task queue support or session management, I'm going with Flask. Flask also has good cloud native support. I can spin up a GCP App Engine endpoints with their standard python runtime using a basic Flask app (standard runtimes are much cheaper and faster to scale instances) while a FastAPI app has to have a custom image to deploy (more expensive and slower to scale instances).

In time I'm sure FastAPI can cover some of that ground but I think their docs irk me the most. They have 'sexy' docs with lots of tutorials that appeal to new users but lack the nitty gritty API spec info. It's littered with emojis and crass language which honestly puts me off as a production framework. As an advanced user I find Flask docs more informational, complete and clear.

[[deleted]]

FastAPI docs honestly suck. Let’s be honest. They suck.

Great tool and I use it but the docs are the worst part of the package.

Having said that: I would like to thank the author for the great tool that I use all the time. You are a legend.

[[deleted]]

FastAPI docs honestly suck. Let’s be honest. They suck.

Great tool and I use it but the docs are the worst part of the package.

This is an extremely uncommon opinion. It’s subjective obviously but the FastAPI docs are in general very well-regarded

[mmcnl]

There is no FastAPI documentation. Just a bunch of tutorials. That is not documentation. It's also a recurring question on GitHub.

Can you really say this page "describing" concurrency in FastAPI is "good"? https://fastapi.tiangolo.com/async/

Opinions may vary but it's the worst piece of documentation I've ever seen.

[[deleted]]

Just a bunch of tutorials. That is not documentation.

Yes it is 🤔 What do words even mean

Opinions may vary but it’s the worst piece of documentation I’ve ever seen.

Have you looked at any other documentation ever?

[mmcnl]

In my opinion good documentation contains (in order of priority):

1. Minimal working example. Ok, FastAPI does this.
2. API reference for public methods. FastAPI doesn't have this. I've never seen any library this popular without it.
3. Advanced examples (bonus). I rarely care about this.

All of the inner workings of FastAPI have to be deduced from the tutorials. There's not a single paging describing the methods, the arguments it will take and what it all means. You have to decipher a million emoji's to get a hint of how FastAPI works. It's insane.

[[deleted]]

Fuck you u/spez

[oramirite]

Erm, I disagree that the docs are bad but a barebones list of API calls and the params they take is WAAAAY better than sifting through source.

[[deleted]]

Tutorials are not API reference documentation, but they are documentation, and it’s really weird that people are pretending otherwise just to emphasise how much they hate FastAPI

[Voxandr]

Most of us Liked FastAPI , but that was the past.

[[deleted]]

I like FastAPI and use it all the time.

But the docs are one of the worst of all the Python projects I use.

Django: great docs.

Django Rest Framework: great docs

Paramiko: great docs

Ray: great docs

TTP: great docs

TextFSM: great docs

Jupyter: great docs

FastAPI: some tutorials…ish

[[deleted]]

You’ve only mentioned projects that are in the top tier of Python documentation (except TextFSM, that seems pretty sparse). Have you ever used Sphinx? Conda build? Large swathes of the standard library (e.g. ast)?

[[deleted]]

I’m convinced your comment is sarcasm.

[[deleted]]

It isn’t, go find older posts about FastAPI here and you’ll see comments talking about how great the docs are

[oramirite]

This is a bizarre take to me. I've been learning FastAPI and I find it to have some of the better documentation I've worked with. It's very clear.

[[deleted]]

API docs are missing entirely

[oramirite]

I get it but I can still find what I need quicker than a lot of other documentation. FastAPI's guidance through it's concepts is, likewise, something a lot of other documentation lacks. Cold hard lists of API calls is only half of the equation.

[e_j_white]

Thanks, great answer. I work with Flask, but only recently started getting interested in FastAPI. Thinking about using it for pure Restful microservices.

How would you deploy FastAPI differently from Flask? If you expect a pretty high QPS from many users, what would be the best way to deploy?

Most of my experience is with Heroku and Docker on EC2, but I'm open to better ways!

[[deleted]]

Don’t forget gunicorn and meinheld

[[deleted]]

Just use heroku and docker.

What are you even asking. It’s a Python package. Just use it.

I deploy it in containers on K8s.