Reusable enums support

I’m submitting a…

[ ] Regression 
[ ] Bug report
[x ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Currently enums are not defined under components section

"components": {
    "schemas": {
        "Album": {
            "type": "object",
            "properties": {
                "direction": {
                    "type": "string",
                    "enum": [
                        "Up",
                        "Down",
                        "Right",
                        "Left"
                    ]
                }
            }
        }
    }
}

Expected behavior

"components": {
    "schemas": {
        "direction": {
            "type": "string",
            "enum": [
                "Up",
                "Down",
                "Right",
                "Left"
            ]
        },
        "Album": {
            "type": "object",
            "properties": {
                "direction": {
                    "schema": {
                        "$ref": "#/components/schemas/direction"
                    }
                }
            }
        }
    }
}

Minimal reproduction of the problem with instructions

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

OpenApi 3 allows us to reference enums under components section to use them multiple times. See the “Reusable Enums” section here https://swagger.io/docs/specification/data-models/enums/

It would allow us to get enums types on the front side too with classes, using a generator like ng-openapi-gen for example, which would be amazing.

Environment

Nest version: 4.0.0-next.2

 
For Tooling issues:
- Node version: XX  
- Platform:  

Others:

[nartc]

There is one caveat about this feature which is getting the Enum name at runtime. One possible solution without adding more property to ApiProperty is to have: enum: to accept a lazily-evaluated function as follow:

enum Status {
   Inactive = 'inactive',
   Active = 'active'
}

@ApiProperty({enum: () => Status})
status: Status;

This will allow us to grab the Status string as the enum name at runtime to be able to “reuse” it. Any suggestions?

[kamilmysliwiec]

Added in 4.3.0. We’re tracking PR to the docs here https://github.com/nestjs/docs.nestjs.com/pull/1024