Question: Is there hints for validator how to validate $ref?

[KES777]

I am trying to implement openapi validator. I am using Tim Burks schema

In my schema I have next definition:

paths:
  /test:
    post:
      parameters:
        - $ref: '#/components/schemas/Test'

OpenAPI schema defines that paramters maybe parameter definition or reference

"parameters": {
  "type": "array",
  "items": {
    "$ref": "#/definitions/parameterOrReference"
  },
  "uniqueItems": true
},
...
"parameterOrReference": {
  "oneOf": [
    {
      "$ref": "#/definitions/parameter"
    },
    {
      "$ref": "#/definitions/reference"
    }
  ]
},

In my schema I use reference and schema is validated. But it should not, because it refer to wrong resource type: schemas but should refer to parameter

In my validator implementation I may hardcode this check: after ref resolution it should refer to parameter.

Is there a way to provide some hints to validator about type for referenced object?

  "oneOf": [
    {
      "$ref": "#/definitions/parameter"
    },
    {
      "$ref": "#/definitions/reference"
      "$type": "#/definitions/parameter"
    }
  ]

Here $type will provide hint that after resolution the schema should be validated against "#/definitions/parameter" schema. Would it be useful to provide such hints?

[KES777]

Or maybe this variant?

  "oneOf": [
    {
      "$ref": "#/definitions/parameter"
    },
    {
      "allOf": [
        {
          "$ref": "#/definitions/parameter"
        },
        {
          "$ref": "#/definitions/reference"
        },
      ]
    }
  ]

[handrews]

JSON Schema does not have a feature for validating the $ref target.

There is a proposal for such a feature at json-schema-org/json-schema-spec#141 but it's somewhat controversial and unlikely to be considered before draft-09 (the JSON Schema project is currently working on draft-08, and OpenAPI is using draft-04).

[handrews]

Since OAS 3.1 is adopting the most recent JSON Schema draft, and this more of a JSON Schema thing, I think this is better tracked at json-schema-org/json-schema-spec#141

Additionally, the question of requiring (rather than validating) that $refs point to #/components/ is tracked at #2084