VSCode shows Scalar OpenAPI schema 'discriminator' property as any but it has a type defined

Question

Why is discriminator any here? It's supposed to be, and defined as, DiscriminatorObject.

import type { OpenAPIV3_1 } from '@scalar/openapi-types'

const schemas: Record<string, OpenAPIV3_1.SchemaObject> = {}
schemas.foo?.discriminator // <-- discriminator is any, should be DiscriminatorObject

example

What's going on? Is there a way to make the type work?

I'm was thinking the IDE wasn't important as it's the TypeScript Language Server that's supplying the type to the IDE — Snæbjørn
– Snæbjørn, Commented yesterday
Please don't post textual information in the form of pictures. Please see: Why should I not upload images of code/data/errors? If you still need an image, it can complement the textual information. — Sergey A Kryukov
– Sergey A Kryukov, Commented yesterday
Yes, showing any is a known problem. It is not related to a known or unknown type, it is related to the object itself. To work around 1) Add a variable/property to the WATCH list under the Run and Debug container element, 2) Enter it in the Debug Console input line. — Sergey A Kryukov
– Sergey A Kryukov, Commented yesterday

Tim Moore · Accepted Answer · 2025-11-20 22:31:38Z

2

The type definition for OpenAPIV3_1.SchemaObject is:

export type SchemaObject = (ArraySchemaObject | NonArraySchemaObject | MixedSchemaObject | boolean) & AnyOtherAttribute;

The problem is that the schema might be a boolean according to this type, and the intersection with AnyOtherAttribute is distributed across the union. The consequence of this is that TypeScript treats the boolean possibility as potentially having unknown attributes of any type. In my opinion, boolean & AnyOtherAttribute doesn't make sense as a type, and should perhaps be considered a bug in the library.

If you narrow the type of schemas.foo to eliminate the boolean possibility, the type of discriminator is as expected:

import type { OpenAPIV3_1 } from "@scalar/openapi-types";

const schemas: Record<string, OpenAPIV3_1.SchemaObject> = {};
if (typeof schemas.foo === "object") {
  schemas.foo.discriminator;
}

(property) discriminator?: OpenAPIV3.DiscriminatorObject | undefined

edited yesterday

answered yesterday

Tim Moore

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1 Comment

Snæbjørn yesterday

Excellent answer! I feel like I learned something, thank you :)

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