JSON property value type

[Rostyslav Pidburachynskyi]

Library contains good type Primitive, its very useful, it's good idea to have the same type but for types from JSON, something like that: type JSONFieldType = string | number | boolean | null | Record<string, JSONFieldType>; (but with better name)

[Alexey Berezin]

@kitsoRik thank you again for the good suggestion!

At the moment I'm preparing for the conference and will be back next week!

For me the plan sounds good, I really like the idea and most probably we will start adding it soon

cc @krzkaczor

[Rostyslav Pidburachynskyi]

@Beraliv Yeah, this is a good package that I install in all projects where I use TypeScript, and I would like to have there all common types. That's not a problem for me (about your busy status). Anyway, I need this type in my current project and I just put it in my types folder.

FYI, now it looks like this:

export type JsonFieldType =
  | string
  | number
  | boolean
  | null
  | { [path: string]: JsonFieldType }
  | JsonFieldType[];

I'm not sure this is finished implementation, so you need to test all cases.

[Rostyslav Pidburachynskyi]

Hi. Regarding my implementation above, found a strange behaviour with inherited classes.

export type JsonFieldType =
  | string
  | number
  | boolean
//   | undefined // uncomment to fix
  | null
  | { [path: string]: JsonFieldType }
  | JsonFieldType[];

abstract class A {
    method(): JsonFieldType {
        if(Math.random() > 0.5) {
            return { q: 1 };
        }

        return { q: 1 };
    }
}

class B extends A {
    method()/*: JsonFieldType */ { // uncomment to fix
        if(Math.random() > 0.5) {
            return { q: 1 };
        }

        return { w: 1 };
    }
}

Probably - good way to add undefined to the union, or no, IDK.

[Alexey Berezin]

Hmm, that's weird

I tried it here – https://tsplay.dev/WPx85W and doesn't have any issues

What TypeScript do you have?

[Rostyslav Pidburachynskyi]

Hmm, that's weird

I tried it here – https://tsplay.dev/WPx85W and doesn't have any issues

What TypeScript do you have?

Yeah, because you uncommented some strings. It works fine without undefined (only with implicitly defined return type of method)

[Alexey Berezin]

Hmm, that's weird
I tried it here – https://tsplay.dev/WPx85W and doesn't have any issues
What TypeScript do you have?

Yeah, because you uncommented some strings. It works fine without undefined (only with implicitly defined return type of method)

Ah, sorry, I needed to have it without uncommenting

[Alexey Berezin]

Also this can be connected with the future implementation of JsonFieldType – #276

[Alexey Berezin]

Also found interesting implementation here – microsoft/TypeScript#1897 (comment)

[Alexey Berezin]

Hey @rpidburachynskyi! I'm planning to include it in the next minor change, would you be interested in having this type now?

I'm planning to implement JsonPrimitive, JsonObject, JsonArray and JsonValue based on https://www.rfc-editor.org/rfc/rfc8259#section-3