fix enum schema

[eugleenyc]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

As outlined in the issue 2761: The schema is being overwritten in apiHeader if an enum is provided.

A demo repo with instructions can be found at https://github.com/eugleenyc/swagger-fix-demo/

How to see the defect:

• clone the repo https://github.com/eugleenyc/swagger-fix-demo/
• run npm install
• run npm start
• go to http://localhost:3000/yaml

The resulting yaml will show the following:

openapi: 3.0.0
paths:
  /:
    get:
      operationId: AppController_getHello
      parameters:
        - name: testHeader
          required: true
          in: header
          description: test description
          schema:
            enum:
              - an enum
            type: string
      responses:
        '200':
          description: ''
info:
  title: demo project
  description: demo project description
  version: '1.0'
  contact: {}
tags:
  - name: demo
    description: ''
servers: []
components:
  schemas: {}

This is not correct as in the controller it specifies a default value.

Issue Number: 2761

What is the new behavior?

As outline in the repo here for the potential swagger fix.
If you include a spread operator in the code outlined here

It will now return the resulting correct yaml file:

openapi: 3.0.0
paths:
  /:
    get:
      operationId: AppController_getHello
      parameters:
        - name: testHeader
          required: true
          in: header
          description: test description
          schema:
            type: string
            default: default param
            enum:
              - an enum
      responses:
        '200':
          description: ''
info:
  title: demo project
  description: demo project description
  version: '1.0'
  contact: {}
tags:
  - name: demo
    description: ''
servers: []
components:
  schemas: {}

Does this PR introduce a breaking change?

• Yes
• No

Other information

[kamilmysliwiec]

Not sure but this may lead to unsupported attributes in the schema

[kamilmysliwiec]

Pardon, I didn't realize that you only updated the @ApiHeader decorator. LGTM then