Is there a way to merge or subtype type references in AsyncAPI

Question

I have an AsyncAPI document that defines a message with an existing payload type.

channels:
  onboarding-consumption:
    publish:
      operationId: publishConsumptionEvent
      summary: Notify of application usage for consumption reporting purposes.
      message:
        name: consumptionEvent
        title: Consumption Event
        headers:
          $ref: "#/components/schemas/message-header"
        correlationId:
          $ref: "#/components/correlationIds/defaultCorrelationId"
        payload:
          $ref: "#/components/schemas/consumption"
        tags:
          - name: onboarding

Effectively I want to use the same existing payload type, but I want to add additional properties to that payload type, but in a different message definition. Is there a way to subtype (and potentially override) a schema or to merge schemas? The same question would apply to header types as well.

score 1 · Accepted Answer · answered Oct 18 '22 at 14:28

it is more related to JSON Schema. JSON Schema is one of many different formats you can use in AsyncAPI to describe your message payload definition.

In your case I believe you need allOf JSON Schema feature. More details in official docs

Below example, I extracted from this article.

subscriptionStatusCommon is the part that is the same in subscriptionStatusError and subscriptionStatusSuccess.

schemas:
    subscriptionStatusError:
      allOf:
        - properties:
            errorMessage:
              type: string
          required:
            - errorMessage
        - $ref: '#/components/schemas/subscriptionStatusCommon'
    subscriptionStatusSuccess:
      allOf:
        - properties:
            channelID:
              type: integer
              description: ChannelID on successful subscription, applicable to public messages only.
            channelName:
              type: string
              description: Channel Name on successful subscription. For payloads 'ohlc' and 'book', respective interval or depth will be added as suffix.
          required:
            - channelID
            - channelName
        - $ref: '#/components/schemas/subscriptionStatusCommon'
    subscriptionStatusCommon:
      type: object
      required:
         - event
      properties:
        event:
          type: string
          const: subscriptionStatus
        reqid:
          $ref: '#/components/schemas/reqid'
        pair:
          $ref: '#/components/schemas/pair'
        status:
          $ref: '#/components/schemas/status'
        subscription:
          required:
            - name
          type: object
          properties:
            depth:
              $ref: '#/components/schemas/depth'
            interval:
              $ref: '#/components/schemas/interval'
            maxratecount:
              $ref: '#/components/schemas/maxratecount'
            name:
              $ref: '#/components/schemas/name'
            token:
              $ref: '#/components/schemas/token'

I hope that helps.

Is there a way to merge or subtype type references in AsyncAPI

1 Answers1