Typehole not picking up nulls

[Andrew Daniel]

I've got a typehole as follows:

row is the following in the debugger:

Notice how totalCompensation is null even though the typehole only picks up the string. I would expect the generated type to be totalCompensation: string | null;

I did run this typehole a number of times and it should have picked up the null value before I put a breakpoint here for a screenshot.

[Riku Rouvila]

It definitely seems like a bug. I wasn't able to reproduce it with

const list = ["hello", null];

type AutoDiscovered = any;

list.forEach((val) => {
  console.log(typehole.t3<AutoDiscovered>(val));
});

and keep getting null | string as the output type. Can you verify you have the latest typehole runtime installed (1.6.0)?
I made some fixes earlier, and it's possible that this would now be fixed.

There is a test case that checks that generating the right type from the samples, which leads me to believe that the issue might between the sample storage and the runtime.

[Riku Rouvila]

There also seems to be something off with how json-to-ts generates the types in case of null

With this input

{ __typeholeRootWrapper__: [ { a: 2 }, { a: null } ] }

We get this output

interface RootObject {
  __typeholeRootWrapper__: TypeholeRootWrapper[];
}
interface TypeholeRootWrapper {
  a?: number;
}

I'd expect it to be

interface RootObject {
  __typeholeRootWrapper__: TypeholeRootWrapper[];
}
interface TypeholeRootWrapper {
  a: number | null;
}

There's actually an issue about the exact problem MariusAlch/json-to-ts#17

[Andrew Daniel]

Yeah I wonder if these are related. Perhaps json-to-ts just doesn't handle nulls well

[Riku Rouvila]

I've now forked json-to-ts and fixed the null handling. The fix is available in release https://github.com/rikukissa/typehole/releases/tag/1.6.2 . See if upgrading the extension and the runtime package would fix this. I'll close this issue for now, but please reopen if it still happens