Prisma.JsonValue type is incompatible with Typescript JSON.parse typing

How to reproduce

import { Prisma } from "@prisma/client";

function parsePrisma(json: Prisma.JsonValue) {
  JSON.parse(json); 
  // Argument of type 'JsonValue' is not assignable to parameter of type 'string'.
  // Type 'null' is not assignable to type 'string'.
}

Expected behavior

It’s arguable that Prisma’s typing is better than Typescript’s - JS JSON.parse indeed accepts nulls, numbers etc. I would still expect the typings to match, so that I don’t have to typecast every time I parse the database response.

Prisma information

2.20.1

[aqrln]

Just checked, and at least in PostgreSQL the return is indeed an already parsed object. We migrated from MySQL to Postgre since then, so maybe it wasn’t the case with MySQL driver, or maybe our database was weirder then?

Oh, I see. That would sound like a bug if it returned a JSON string to you instead of an actual value. I can’t reproduce it with the latest Prisma with MySQL, but I wonder if something might have gone wrong back then.

I’d love a way to easily get stronger type on a Json field, but that’s a different topic altogether.

Yes, it’s a popular feature request (https://github.com/prisma/prisma/issues/3219), and we’d love to have this too, but I can’t share any specific timeline. Now that we support composite types for embedded documents in MongoDB we’re one step closer to typed JSON fields in relational databases as well though.

Sorry about the confusion, I guess?

No worries! Should I go ahead and close this issue?

[Faithfinder]

json as any or json as string, doesn’t matter. Typescript JSON.parse definition isn’t too helpful, it’s not even generic.

parse(text: string, reviver?: (this: any, key: string, value: any) => any): any;

// obviously dummy code
function parsePrisma(json: Prisma.JsonValue) {
  return JSON.parse(json as string) as WhatIExpectTheJsonToBe;
}

This issue is just about not having to type as string each time.