Optional parameters with `default` are generated as required

[isweetland]

Description

An optional field in the openapi schema that includes the default property is generated as required in typescript

Name	Version
openapi-typescript	7.4.3
Node.js	18.19
OS + version	macOS 14.2.1

Reproduction

The following openapi schema is used:

{
  "openapi": "3.1.0",
  "info": {
    "title": "Config Service",
    "version": "local"
  },
  "paths": {
    "/config": {
      "post": {
        "summary": "Set Config",
        "operationId": "set_config_v1_config_post",
        "parameters": [],
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "anyOf": [
                  {
                    "$ref": "#/components/schemas/ConfigIn"
                  },
                  {
                    "type": "null"
                  }
                ],
                "title": "Params"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {
                  "type": "null",
                  "title": "Response Set Config Post"
                }
              }
            }
          }
        }
      },
    }
  },
  "components": {
    "schemas": {
      "ConfigIn": {
        "properties": {
          "interval": {
            "anyOf": [
              {
                "type": "integer"
              },
              {
                "type": "null"
              }
            ],
            "title": "Interval",
            "default": 1
          },
          "start_at": {
            "anyOf": [
              {
                "type": "string",
                "format": "date-time"
              },
              {
                "type": "null"
              }
            ],
            "title": "Start At"
          }
        },
        "type": "object",
        "required": [],
        "title": "ConfigIn"
      }
    }
  }
}

Running npx openapi-typescript ./schema.json -o ./types.ts

The following type for ConfigIn is generated:

ConfigIn: {
    /**
     * Interval
     * @default 1
     */
    interval: number | null;
    /** Start At */
    start_at?: string | null;
};

Expected result

I expect interval to be marked optional as well

ConfigIn: {
    /**
     * Interval
     * @default 1
     */
    interval?: number | null;
    /** Start At */
    start_at?: string | null;
};

Checklist

• [ ] My OpenAPI schema passes the Redocly validator (npx @redocly/cli@latest lint)
• [ ] I’m willing to open a PR (see CONTRIBUTING.md)

[isweetland]

Possible duplicate of https://github.com/openapi-ts/openapi-typescript/issues/1957

[kylebebak]

I'm currently handling this bug with post-processing. I wrote a janky Python script to parse the generated schema.d.ts file and fix the output for the cases described in this issue

It'd be great to get this fix into the library!

[mgfinch]

Add the flag --default-non-nullable false when generating schema.

[suiramdev]

He is right, `--default-non-nullable false' solves the problem. I think this is intended, because this default value is not essentially set on the code end, after all.

[hathawsh]

My code got bitten by this issue. I was previously using version 6 or earlier. The --default-non-nullable false fix worked.

Respectfully, I'd like to understand why this new command line parameter is needed. I checked a few versions, and it appears versions 7.0 through 7.8 now convert optional properties with a default value to required, unless I specify --default-non-nullable false. Shouldn't optional properties remain optional, regardless of the existence of a default value?