Type check errors when loading from json file

[shot-codes]

openapi-typescript version

7.9.1

Node.js version

24.5.0

OS + version

NixOS 25.11

Description

I'm trying to load a request body from a json file. When I do that i get type errors on the assignment to a variable that is annotated with the corresponding type. If I manually construct the json inline typescript is totally happy. The error I get is Type 'string' is not assignable to type '"bar"'. I can try to provide more information if it will help. But I can't share my actual types/api so it will require a little bit of work.

<script lang="ts">
    import type { components } from "./mySchema";

    // Typescript is happy here
    let x: components['schema']['MyType'] = { foo: "bar" }

    // Typescript gives me type errors here
    import data from './example.json';
    let x: components['schema']['MyType'] = data
</script>

example.json:

{ "foo": "bar" }

Reproduction

If needed I can try to make a minimal reproduction. But I first wanted to hear if this is expected/trivial to solve.

Expected result

Expecting no type errors

Required

• My OpenAPI schema is valid and passes the Redocly validator (npx @redocly/cli@latest lint)

Extra

• I’m willing to open a PR (see CONTRIBUTING.md)

[shot-codes]

It is happy if I stringify and then parse the json:

let x: components['schema']['MyType'] = JSON.parse(JSON.stringify(data));

Or if I do the following:

let x: components['schema']['MyType'] = data as components['schema']['MyType'];

[evermake]

This issue is unrelated to openapi-ts.

---

When you do:

let x: components['schema']['MyType'] = { foo: "bar" }

TypeScript can understand that object literal matches the expected type of the variable.

---

When you do:

import data from './example.json';
let x: components['schema']['MyType'] = data

TypeScript infers the type of data as { "foo": string }, which is why you get Type 'string' is not assignable to type '"bar"'.

---

When you do:

let x: components['schema']['MyType'] = JSON.parse(JSON.stringify(data));

Return type of JSON.parse is any, and since any is assignable to anything, TypeScript does not complain.

---

I suggest to close this issue and do one of the following:

1. Open issue in TypeScript repo
2. Replace you example.json with example.ts and use export default {/* ... */} as const
3. Use typecast as components['schema']['MyType']
4. Use some validation library (e.g. zod), if you need strong type-safety and can only use.json