lucis•3y ago

Converting Typescript Types to JSON Schema (Props definition)?

Folks, We're creating a CMS solution using Deno and Fresh. For our product goals, we want to dynamically extract how UI components are configured using their Props declaration. Example: For this component

interface Props {
  title: string
  numberOfLines: number 
}

export default MyComponent(props: Props) {
  return <div>.,.
}

interface Props {
  title: string
  numberOfLines: number 
}

export default MyComponent(props: Props) {
  return <div>.,.
}

we should be able to extract (in dev time, we have a slight "build process" already in place) the Props declaration, and be able to generate a form for that. To generate the Form, we're using JSON Schema + react-json-schema-form (https://react-jsonschema-form.readthedocs.io/en/latest/) and, for that to happen, we need to transform the file above into a JSON Schema that defines exactly the data for that component's props. The question is: how can we accomplish that in a reliable way? We have a proof of concept working where we use deno doc file.ts --json (https://github.com/deco-cx/live/blob/main/utils/denoDoc.ts) and it's ok, but we need to manually "map" everything. Right now, we don't support Array<CustomObject> as a type for a prop, for example. We believe that there must be a more "native" way, that uses the same AST/metadata that Deno uses, that will handle most case for us. Edge cases are: - props with custom types defined elsewhere in the module and referenced in the props declaration. - props with types imported from other files - props with types imported using import_map.json We're aware of https://github.com/YousefED/typescript-json-schema but I'm pretty sure that it'll differ slightly to how Deno works. Do you have any suggestions?

7 Replies

lucisOP•3y ago

cc @guifromrio @brasileiro_ @tgimenes

Unknown User•3y ago

Message Not Public

Leokuma•3y ago

An AST-based solution sounds too complex for a CMS. Personally I would avoid that strategy Can't you export the Props interface and import it in another script which would then generate and save the JSON schema to the filesystem? I guess you can iterate over Props with for in, Object.keys or something

Moomoo•3y ago

This sounds like the same sort of problem that io-ts and morphic-ts attempt to solve, have you looked into those?

Sorikairo•3y ago

I would suggest that you look into decorators with “emitDecoratorMetadata” compilers option and “design:paramstype”, “design:type” metadata. This is what I use to generate open api schema from ts code. Yes it forces you to add decorators to your component and classes, but it can also be a way to white list what you want to generate schema for 😃

lucisOP•3y ago

types in typescript are not something you can iterate over, there's no reflection for that. that's the main problem and why we need go to AST parsing

Leokuma•3y ago

I knew I must be missing something 😅