Support `default` in `schema.$ref` for enums

[chiragjn]

Is there an existing issue that is already proposing this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe it

I have gone through #2898 and #1041

My code looks like this

export enum LogsSearchOperatorType {
  EQUAL = 'equal',
  NOT_EQUAL = 'not_equal',
}

export class GetApplicationLogsQuery {
   ...
   @ApiPropertyOptional({
    enum: LogsSearchOperatorType,
    enumName: 'LogsSearchOperatorType',
    default: LogsSearchOperatorType.EQUAL,
    enumSchema: {
      description: 'Comparison operator logs search',
    },
    description: 'Comparison operator for filter. `equal` or `not_equal`',
  })
  @IsOptional()
  searchOperator?: LogsSearchOperatorType = LogsSearchOperatorType.EQUAL;
}

GetApplicationLogsQuery is used as query params in a route.

My goal is to have a default on this enum in this specific context.

While enumSchema has a field default, I do not want to declare the default there because this enum is shared across multiple places.

OAS 3.1.0 now allows default in schema as sibling of $ref

but nestjs/swagger removes all such fields in here:

swagger/lib/services/swagger-types-mapper.ts

Line 44 in f2444df

return this.omitParamKeys(param);

And I get

{
            "name": "searchOperator",
            "required": false,
            "in": "query",
            "description": "Comparison operator for filter. `equal` or `not_equal`",
            "schema": {
              "$ref": "#/components/schemas/LogsSearchOperatorType"
            }
}

---

Example OAS 3.1 spec that can be tried at https://editor-next.swagger.io/

openapi: "3.1.0"
info:
  title: Enum default
  version: '0.1.0'
paths:
  /products:
    get:
      parameters:
        - in: query
          name: color
          required: false
          schema:
            $ref: "#/components/schemas/Color"
            default: "black"
      responses:
        "200":
          description: OK
components:
  schemas:
    Color:
      type: string
      enum:
        - black
        - white
        - red
        - green
        - blue

Describe the solution you'd like

Take the default from @ApiProperty and place it in schema

Teachability, documentation, adoption, migration strategy

No response

What is the motivation / use case for changing the behavior?

Correct defaults for downstream docs and SDK generation