ts-simple-type VS openapi-typescript

We use an internal validator library that we infer request types from. It’s similar to Zod (but also predates it by a year).

I’ve also spent some time on a Typescript type to X compiler. My first prototype is open source and targets Thrift, Proto3, Python, and JSON schema: https://github.com/justjake/ts-simple-type/tree/main/src/com...

I’m not happy with the design decision in that codebase to try to “simplify” Typescript types before compiling, and probably won’t continue that implementation, but we have a few internal code generators that consume TS types and output test data builders and model clases we use in production.

After some frustration with the TypeScript schema library ecosystem, I've decided that I'd prefer to declare my types using TypeScript's excellent type syntax, so I can take advantage of generics, mapped types, etc. Then, I'll take those TypeScript types and compile them to whatever alternative schema format I need.

There are many libraries that claim to convert your Typescript types to other formats, such as ts-json-schema-generator, ts-to-zod, or typeconv/core-types-ts. These libraries work by interpreting the Typescript AST, essentially re-implementing a bare-bones type system from scratch. Most do not support advanced Typescript features like generic application, mapped types, or string literal types. So, what's the point? To avoid those limitations, I use Typescript's first-party ts.TypeChecker API to analyze types, and an existing library called ts-simple-type (which I've forked) to convert from ts.Type to a more usable intermediate format. Then, I recurse over the intermediate format and emit "AST nodes". It's pretty simple, but seems promising.

So far, I have compilers from TypeScript type to Python 3 and Thrift. But I plan to add OpenAPI/JSONSchema, Protobuf (Proto3), Kotlin, Swift, and maybe Zod and Avro. Each target language is around ~300 LoC so they're pretty easy to put together.

Repo: https://github.com/justjake/ts-simple-type

Compiler input and output: https://github.com/justjake/ts-simple-type/blob/jake--compil...

Thrift compiler: https://github.com/justjake/ts-simple-type/blob/jake--compil...

Python compiler: https://github.com/justjake/ts-simple-type/blob/jake--compil...

OpenAPI TypeScript

I'll preface all of this with a couple esoteric design goals that I had in mind:

1. I actually _want_ an SPA. You might not need an SPA, if you don't need one then Vue/React/etc are overkill, etc.

2. I want to power as much of the SPA as I can using the same REST API as my core product, both for dogfooding reasons and for consolidation. Many people might argue that this is a bad idea.

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With that in mind, some specific packages that I highly recommend:

1. Django-vite (https://github.com/MrBin99/django-vite). This makes it very easy to serve an SPA from the actual django response/request model

2. Some sort of way to get type information (if you're using TypeScript) into the frontend. I use a frankensteined system of the OpenAPI spec that django-ninja generates + openapi-typescript (https://github.com/drwpow/openapi-typescript). This means when I add, say, a new field to a response in Django, I immediately get typechecking for it in Vue — which has been _tremendously_ useful.

3. Django-typescript-routes (a package I extracted and open-sourced!: https://github.com/buttondown-email/django-typescript-routes) which gives your front-end routing information based on the Django router.

Glad to see alternatives but disappointed that Bruno does not support OpenAPI specification.

At my company, we hand-edit OpenAPI specs in YAML and it gets consumed by many tools that generate types[0], static analysis and dynamic checks[1]. The OpenAPI spec itself is linted[2]. And of course, Postman consumes OpenAPI.

Tools that are built on open standards will naturally see greater adoption over those that use proprietary formats.

[0]: https://openapi-ts.pages.dev

Another great library to generate TS types from OpenAPI is https://github.com/drwpow/openapi-typescript . It provides the types as single objects you access via indexing, which is pretty nice. There's a partner library to generate a typed fetch client.

If you're willing to document your API with an OpenAPI schema, then it should be possible to generate TypeScript types based on the OpenAPI schema with something like openapi-typescript. Also, Typebox can generate JSON schemas, maybe it can be used to generate something that the front-end can also use?

REST

In this sample, we'll achive it using openapi-typescript and openapi-typescript-fetch.