Swagger: Additional properties not allowed: allOf - swagger

Question

I'm trying to figure out this swagger API inheritance stuff by using allOf. This is my swagger yaml file.
swagger: '2.0'
info:
title: Test API
version: '1'
basePath: /api/v1
schemes:
- https
produces:
- application/json
paths:
/users:
get:
summary: Collection of users
tags:
- users
responses:
200:
description: A list of Users
schema:
$ref: "#/definitions/Users"
500:
$ref: "#/responses/BadRequest"
definitions:
User:
required:
- username
properties:
firstName:
type: string
lastName:
type: string
username:
type: string
Users:
type: array
items:
$ref: "#/definitions/User"
responses:
NonSuccess:
description: Generic response for all non-success responses
schema:
type: object
required:
- code
- message
properties:
code:
type: integer
description: The success code, 0 or -1.
message:
type: string
description: The description message for this success code
errors:
type: array
description: A map of errors within the request. Keyed by the parameter name and the values are the error details
BadRequest:
description: Invalid request parameters
allOf:
- $ref: "#/responses/NonSuccess"
When I paste this into the online editor, I get the following errors that I'm having a real hard time trying to figure out.
✖ Swagger Error
Additional properties not allowed: allOf
Jump to line 60
✖ Swagger Error
Not a valid response definition
Jump to line 22
The main problem seems to be Additional properties not allowed: allOf and I'm can't seem to figure out what I'm doing wrong in this case. I was trying to declare a basic non-success response so that all non-200 responses will inherit so that the API will have a very standard looking non-success response. I was under the impression I could do this with allOf and then add or overwrite the fields from that response. What exactly am I doing wrong?

Answer 1

The allOf tag can only be used on Schema objects. You can definitely use it on the Schema portion of the response, though. Here's an example of that.
swagger: '2.0'
info:
title: Test API
version: '1'
basePath: /api/v1
schemes:
- https
produces:
- application/json
paths:
/users:
get:
summary: Collection of users
tags:
- users
responses:
200:
description: A list of Users
schema:
$ref: "#/definitions/Users"
500:
$ref: "#/responses/BadRequest"
definitions:
User:
required:
- username
properties:
firstName:
type: string
lastName:
type: string
username:
type: string
Users:
type: array
items:
$ref: "#/definitions/User"
Response:
type: object
required:
- code
- message
properties:
code:
type: integer
description: The success code, 0 or -1.
message:
type: string
description: The description message for this success code
errors:
type: array
description: A map of errors within the request. Keyed by the parameter name and the values are the error details
BadRequest:
type: object
required:
- validationErrors
properties:
validationErrors:
type: array
items:
type: string
responses:
NonSuccess:
description: Generic response for a non-success
schema:
$ref: "#/definitions/Response"
BadRequest:
description: Invalid request parameters
schema:
allOf:
- $ref: "#/definitions/Response"
- $ref: "#/definitions/BadRequest"