Type error when returning `JsonObject` from Prisma/`type-fest` when returning from server function

[dccarmo]

Which project does this relate to?

Start

Describe the bug

I have an object being returned from Prisma that accepts JSON as one of the properties (typed as JsonObject from type-fest).

When returning it from a server function, TypeScript gives me this error:

Type 'JsonObject' is not assignable to type 'string | number | boolean | { [x: string]: string | number | boolean | ... | { [x: number]: string | number | boolean | ... | ... | null; length: number; toString: "Function is not serializable"; ... 32 more ...; readonly [Symbol.unscopables]: { ...; }; } | null | undefined; } | { ...; } | null'.

Type 'JsonObject' is missing the following properties from type '{ [x: number]: string | number | boolean | { [x: string]: string | number | boolean | ... | ... | null | undefined; } | ... | null; length: number; toString: "Function is not serializable"; ... 32 more ...; readonly [Symbol.unscopables]: { ...; }; }': length, pop, push, concat, and 29 more.

It seems to me that the handler call from createServerFn expects a JSON value in a specific format that doesn't match what JsonObject is.

Your Example Website or App

https://stackblitz.com/edit/github-ejdg28er?file=src%2Futils%2Fposts.tsx

Steps to Reproduce the Bug or Issue

Return an object that has a property with type JsonObject from type-fest.

Expected behavior

As a user, I'd expect TS to not return any errors (to return the data type in whichever format I need without complaining)

Screenshots or Videos

No response

Platform

• OS: macOS
• Browser: Firefox
• Version: 1.115.2

Additional context

No response

[m4rvr]

I think I have a similar issue with the error Type '{ [key: string]: unknown; }' is not assignable to type '{ [x: string]: {}; }'. It converts unknown to {}, but only in an object.

Returning const foo: unknown = 1 works just fine

[obs-gh-corygorman]

Were you able to solve this?

[m4rvr]

Were you able to solve this?

I don't think there is a solution (yet?) to this according to issue #4411. I suppressed the error with // @ts-expect-error or if I don't need the content in the return (just name or description of the record), just return those fields instead of the whole object with unknown json fields. Not a real solution though.

[schester44]

yeah this one is pretty annoying especially when the JsonObject is deeply nested and you're deriving types from Prisma.ModelGetPayload

[obs-gh-corygorman]

I was able to work around this using https://www.npmjs.com/package/prisma-json-types-generator

[schiller-manuel]

does this issue still exist on the latest version?

[m4rvr]

does this issue still exist on the latest version?

Not sure if the Prisma issue is different but with this code in the loader I still get that error.

const data: Record<string, Record<string, unknown>> = {
  foo: {
    bar: 'boo'
  }
}

return {
  data
}

Type 'Record<string, unknown>' is not assignable to type '{ [x: string]: {}; }'.
                'string' index signatures are incompatible.
                  Type 'unknown' is not assignable to type '{}'

So I guess according to #4411 this is still the correct behavior?

[schiller-manuel]

yes

[dccarmo]

Should I close this issue if this is the expected behavior?

[jofflin]

I have the same issue.
For me:
I provide metadata as optional detailled information:

(property) metadata: {
    [key: string]: unknown;
}

If I set a object that contains metadata (basically all objects I retreive with ensureQueryData in beforeLoad) I get the same error

Type '{ [key: string]: unknown; }' is not assignable to type '{ [x: string]: {}; }'.
'string' index signatures are incompatible.
            Type 'unknown' is not assignable to type '{}'.ts(2322)