json-schema-to-typescript
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bcherny
`additionalProperties` union clashes with defined properties
A schema of:
{
"type": "object",
"properties": {
"$schema": {
"description": "The JSON schema reference.",
"type": "string"
},
},
"additionalProperties": {
"type": "object"
}
}
resolves to:
export interface MySchema {
/**
* The JSON schema reference.
*/
$schema?: string;
[k: string]: {
[k: string]: unknown;
};
}
which is an incompatible type, as $schema clearly doesn't follow { [k: string]: unknown }.
You can see the error in the typescript playground.
I encountered this here: https://dprint.dev/schemas/v0.json which is the schema for the dprint configuration. (cc @dsherret)
A potential fix is to generate additionalProperties as:
[k: string]: {
[k: string]: unknown;
} | unknown;
Test code:
const { compile } = require('json-schema-to-typescript');
// or, compile a JS object
let mySchema = {
"type": "object",
"properties": {
"$schema": {
"description": "The JSON schema reference.",
"type": "string"
},
},
additionalProperties: {
type: "object"
}
}
compile(mySchema, 'MySchema')
.then(console.log)
This is tricky. We want to say "additional properties should be X, but not Y". I worry that unioning with unknown is too permissive.
This is a TypeScript feature request, tracked here: https://github.com/microsoft/TypeScript/issues/17867.
ACK. For the time being the generated types are unusable however, the way they are generated. I think unioning with unknown is not ideal but in the meantime, until there is a better way to to express this, it might be better than what is currently generated?
On Mon, 13 Sep 2021, 07:08 Boris Cherny, @.***> wrote:
This is tricky. We want to say "additional properties should be X, but not Y". I worry that unioning with unknown is too permissive.
This is a TypeScript feature request, tracked here: microsoft/TypeScript#17867 https://github.com/microsoft/TypeScript/issues/17867.
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