Stuck on an issue?

I recently ran into an issue testing some of my more complex schema documents where combination schema $refs cannot be resolved properly if they are part of an “extended” $ref. It is a little hard to explain the case, but I think I have found a simple enough schema that causes the problem to occur.

// base.json
{
  "type": "object",
  "properties": {
    "some_value": { "$ref": "defs.json#/definitions/astring" }
  }
}

//

{
  "definitions": {
    "astring": {
      "description": "astring",
      "$ref": "defs2.json#/definitions/bstring"
    }
  }
}


// defs2.json
{
  "definitions": {
    "bstring": {
      "oneOf": [
        {
          "$ref": "#/definitions/cstring"
        },
        {
          "$ref": "#/definitions/dstring"
        }
      ]
    },
    "cstring": {
      "type": "string"
    },
    "dstring": {
      "type": "number"
    }
  }
}

The error that I see when trying to resolve this looks like: Error while processing route: dynamic-form Token "cstring" does not exist. MissingPointerError: Token "cstring" does not exist.

This only seems to happen when the intermediate schema object is an “extended” ref. For example, if we remove the description from astring then we are able to dereference without issue. From doing some debugging it looks to me like our issue is that when resolving cstring, the path we resolve is defs.json#/definitions/cstring instead of looking in defs2.json. I think this is because when we resolve extended $refs, we explicitly do not update the pointer’s path.

For reference: https://github.com/APIDevTools/json-schema-ref-parser/blob/13b00923fb279cfcb2a72e0906f3eadc13199d08/lib/pointer.js#L240-L245

I would like to propose a fix, but feel ill-equipped to do so without some guidance. It does seem like updating the path in the above code fixes my specific issue, but clearly that decision was made for a reason so I’d rather not step on any toes without understanding the intent. Any thoughts would be greatly appreciated!