Invalid typescript generated when using circular types

[TimoGlastra]

Description

When using circular types (e.g. JsonObject where each value is JsonValue and JsonValue can in turn be a JsonObject) the generated typescript is invalid and won't compile.

The model generated is as follows:

export type JsonValue = JsonObject | string | number | boolean;

export type JsonObject = Record<string, JsonValue>;

However, TS supports circular references if you use this syntax:

export type JsonValue = JsonObject | string | number | boolean;

export type JsonObject = { [key: string]: JsonValue };

Would it be possible to change the way records are typed, or could an exception be made for circular types (this may be hard to detect, so always using the first syntax might be simpler)

OpenAPI specification (optional)

{
	"openapi": "3.1.0",
	"info": { "version": "0" },
	"components": {
		"schemas": {
			"JsonValue": {
				"anyOf": [
					{
						"$ref": "#/components/schemas/JsonObject"
					},
					{
						"type": "string"
					},
					{
						"type": "number"
					},
					{
						"type": "boolean"
					}
				]
			},
			"JsonObject": {
				"type": "object",
				"additionalProperties": {
					"$ref": "#/components/schemas/JsonValue"
				}
			}
		}
	}
}

Configuration

No response

System information (optional)

No response

[jordanshatford]

@TimoGlastra thanks for the issue report. I don't see why we wouldn't be able to use the syntax that works. It should be fairly simple to implement.

Cc: @mrlubos thoughts?

[mrlubos]

@jordanshatford Feel free to change this, but leave a comment please explaining why we need that syntax

[jordanshatford]

@TimoGlastra I have a PR up using the { [key: string]: string } syntax. This will be in the next release. Thanks for reporting the issue.

Side note: both syntaxs act the same so this change is not breaking (Record<string, string> === { [key: string]: string })

[jashaj]

This does have a side effect which forced me to change existing code. When iterating over the keys, TypeScript sees the key as string | number. With a Record, the key was guaranteed to be a string.

[jordanshatford]

@jashaj could you create a new issue and provide examples of your code. For me the following is true:

1. Both someVar: Record<string, string> and someVar: { [key: string]: string } allow someVar[1] = 'test'.
2. When I Object.keys(someVar).forEach TypeScript things they are string.

I would need to see generated code to help with this issue (please under a newly created issue). Everywhere I have looked they are equivalent.