trpc-openapi VS openapi-typescript-codegen

tRPC does not natively export OpenAPI documents, but the trpc-openapi package adds this functionality. We'll start this tutorial by adding trpc-openapi to a project, and then we'll add a script to generate an OpenAPI schema and save it as a file.

While trpc-openapi originally was used to expose REST endpoints of the tRPC router, we will use it to generate an OpenAPI specification for our API.

Sure it can, you can use https://github.com/prosepilot/trpc-openapi

You either have to go with react native or use https://github.com/jlalmes/trpc-openapi to generate rest endpoint using trpc. lol. Not sure how good the trpc-openapi package is though. Read somewhere it was missing stuff

As for exposing the API externally, neither (can) limit this but SvelteKit's API is generally considered to be an internal implementation detail that you don't use directly since it might change between versions. If you want to expose an API you should choose tRPC, probably alongside the OpenAPI plugin or something similar.

In essence, features of the language made for static type checking at compilation are possibly being left favour of tools that act like a superset of the language that provide the static build type checking and offer runtime type checking too. An example I recently saw was the trpc-openapi package which uses Zod for creating the types of the schema for the http request and responses, it takes a zod schema as that is what it can use when compiled to JavaScript to generate the types for the openapi file at runtime, there's scarcely a type or interface in sight when using it but you have full type safety.

Take a look at https://github.com/jlalmes/trpc-openapi which will give you a rest endpoint based on your trpc router. Ymmv in reality but basically this should give you some confidence that your trpc router can be called from another client (not just next).

Ok thanks, I did find a good example here https://github.com/jlalmes/trpc-openapi/blob/master/examples/with-nextjs/src/server/router.ts

There is an OpenAPI Extension for tRPC that can be used to create a more REST-like API from your procedures, and that in turn can be used for auto-generating documentation. But if my app needed to offer third-party API access, I would likely reach for GraphQL again.

tRPC is nice because you have type safety the whole way down. Someone has made a tRPC OpenaAPI for exposing tRPC procedures externally in the OpenAPI format https://github.com/jlalmes/trpc-openapi

I’d also add that if you use Typescript with an OpenAPI client generator (https://github.com/ferdikoomen/openapi-typescript-codegen) it can immensely alleviate some of the biggest pain points of seperate backend and front-end. It always used to be a major pain in the ass with the amount of overhead an API change would incur - updating documentation, postman, constant communication between backend and front-end devs, etc. Now I just npm run generate, I see new API changes in my Git client and Typescript errors for code that needs updating.

Also, using a library like Tanstack Query or Rdtk Query can almost completely eliminate manual state management, and kinda makes the whole development experience feel almost like SSR.

I have been in love with Loopback.io since v2 even though it was a bit of a rollercoaster.. Loopback v4 is a beautiful library. Its been around longer than nestjs but that's the easiest thing to compare it too. I recently have been creating lb4 servers that interface nextjs and react native clients. Initially, I identify my entities and use cases that I want to build. I then use the lb4 cli to auto generate models, relations, controllers, datasources, interceptors (add logic on methods/classes). I can start testing them with the OpenAPI explorer. With the openapi-typescript-codegen library I can generate services from my lb4 OpenAPI spec that I can use on the client side. From there, you can really query data easily with the loopback filter (which can be used on the client too). I initially started doing this with angular1/2+ but its been pleasant using many clients. Even though I have been leveraging it for years in production, I am still learning and exploring. There are many other awesome things I can expand on or explain if you are interested!

https://loopback.io/doc/en/lb4/

https://github.com/ferdikoomen/openapi-typescript-codegen/tr...

In our current project with a TS frontend and Python backend, we use an OpenAPI schema as the source of truth and openapi-typescript-codegen [0] to interface with it on the client side. While not perfect, it provides a very nice interface to our API with request/response typings.

I also wrote a 10-line mock API wrapper that you can call as mockApi((request) => response), and it will type-check that your mock function implements the API correctly.

[0]: https://github.com/ferdikoomen/openapi-typescript-codegen

Second step is to generate typescript types from the backend's spec. You can use a library like this.

openapi-typescript-codegen Generates a Typescript client with interfaces from an OpenAPI spec.

I'm not familiar with all the options openapi-generator has. I tried it awhile ago and found it quite buggy, and more of a pain to run, especially if you're not already doing Java development. I ended up preferring OpenAPI Typescript Codegen, which is written in Typescript. One option it has which would solve the problem you're running into here, is that you can tell it to use union types instead of enums. So your interfaces would be generated as

I'm currently working on two separate projects, the first is a Django project with DRF and I codegen with drf-spectacular [1] and openapi-typescript-codegen [2]. The other project also uses Django, with the API through Hasura and codegen with graphql-codegen [3]. In both of these cases I've been able to largely avoid duplicating my models clientside, or at least it isn't manual.

1: https://github.com/ferdikoomen/openapi-typescript-codegen

2: https://drf-spectacular.readthedocs.io/en/latest/

3: https://github.com/dotansimha/graphql-code-generator

For typescript client code generation, I typically use something like openapi-typescript-codegen, but there are a lot more generators (like the openapi-generator project) that are imperfect in their own ways, I'm sure you can find one that works for you.