Schema first approach

[jugaadi]

Description

Is it possible to use a schema first approach with FastAPI? We design the APIs(using OpenAPI spec) for a service first and we expect FastAPI to handle the incoming requests based on it.

Additional context

Checkout a similar f/w: https://github.com/zalando/connexion

[euri10]

It's actually the exact opposite that happens, you write your endpoints and the schema is created for you

In theory nothing prevents you from deriving your endpoints coding from it, there's just no automation benefit which would transform the schema into endpoints.

Well to be very clear I'm not aware of such a thing should it exist.

[dmontagu]

@jugaadi I think it would be interesting to have a server stubs generator for FastAPI. Currently, I don't think this exists, but I think it would be pretty easy to throw together a set of templates for this that would be compatible with openapi-generator, which has server stubs generation for other python frameworks.

You can take a look at https://github.com/dmontagu/fastapi_client for an example of what this looks like when generating a client; tweaking it to generate a server shouldn't be too hard beyond modifying the templates and language passed to the openapi-generator call.

[jugaadi]

Thanks @euri10 @dmontagu

[tiangolo]

Thanks for the help here @dmontagu and @euri10 ! 👏 🙇

Thanks for reporting back and closing the issue @jugaadi 👍

[lingster]

Hi, I was just looking for something along the same lines and it looks like there is an attempt here:
https://pypi.org/project/fastapi-code-generator/
hope this helps!

[richarddevers]

For spec-first, connexion do the job: https://github.com/spec-first/connexion , however, it's not faspi :(

https://pypi.org/project/fastapi-code-generator/ do the job, but i don't see the point to automatize this using fastapi.
If you use fastapi, it's to have fine tuning over you api code which is absolutely not the case anymore if you use fastapi-code-generator. It's more a boiler plate to accelerate code writing, you don't want to use it at runtime.

[dannysheridan]

🙌 Inspired by this Issue, my team built this.

A schema-first approach to FastAPI that generates server interfaces for you to implement.

Fern: https://github.com/fern-api/fern/
Discord: https://discord.com/invite/JkkXumPzcG