Refer to self in OpenAPI 3.0

Question

I have a data model definition in OpenAPI 3.0, using SwaggerHub to display the UI. I want one of the properties of a model to be related, which is an array of properties of the same model.

    Foo:
      properties:
        title:
          type: string
        related:
          type: array
          items: 
            $ref: '#/components/schemas/Foo'

The parser doesn't seem to like this - the UI shows the related property as an empty array. Is this kind of self-reference possible in OpenAPI 3.0?

Answer 1

Your definition is correct, it's just Swagger UI currently does not render circular-referenced definitions properly. See issue #3325 for details.

What you can do is add a model example, and Swagger UI will display this example instead of trying to generate an example from the definition.

    Foo:
      type: object
      properties:
        title:
          type: string
        related:
          type: array
          items: 
            $ref: '#/components/schemas/Foo'
      example:     # <-------
        title: foo
        related:
          - title: bar
          - title: baz
            related:
              - title: qux

Alternatively, you can add an example just for the related array:

    Foo:
      type: object
      properties:
        title:
          type: string
        related:
          type: array
          items: 
            $ref: '#/components/schemas/Foo'
          example:   # <--- Make sure "example" is on the same level as "type: array"
            - title: bar
            - title: baz
              related:
                - title: qux