describedby question

[Ognian]

I'm having the following schema

"properties": {
                "_id": {
                    "type": "string",
                    "title": "ID"
                },
                "oM":{
                    "type":"object",
                    "name":"object metadata",
                    "properties": {
                        "n":{
                            "type": "string",
                            "title": "collection name"
                        },
                        "u":{
                            "type": "string",
                            "format": "uri",
                            "title": "Schema URL"
                        }
                    }
                },
                "oD":{
                    "type":"object",
                    "name":"object data",
                    "title":"document",
                    // here comes the "magic" to reference the schema by an attribute in the instance of the schema
                    "links": [{
                        "rel": "describedby",
                        "href": "{+(oM.u)}"       //see http://tools.ietf.org/html/rfc6570 and http://json-schema.org/latest/json-schema-hypermedia.html#anchor18
                    }]
                }

what is the correct value of "href" to refer to the "Schema URL"?
Thanks a lot
Ognian

[geraintluff]

Ah - you want to refer to a property that is not an immediate sibling, but instead two levels deep (oM -> u).

That's unfortunately not possible with the v4 version of the spec. :(

It is a [proposed feature for v5](https://github.com/json-schema/json-schema/wiki/Extended-templating-syntax-(v5-proposal\)), however - and when v5 is released then I'll put it into Jsonary immediately.

[Ognian]

Ok, I changed the schema to

 "sche":{
                     "type": "string",
                     "format": "uri",
                     "title": "Schema URL"
            },
"oD":{
                    "type":"object",
                    "name":"object data",
                    "title":"document",
                    "links": [{
                        "rel": "describedby",
                        "href": "{sche}" 
                    }]
                }

but I'm still not able to tell jsonary what schema to use for "oD"...
Is the href syntax wrong or shall I omit type, name titel...

[Ognian]

Ok, I found it:

1. "sche", the atribute containing the schema must be a property of "oD".
2. href should be "{+sche}"

Yes indeed the proposed feature for v5 would better solve my problem...
Thanks
Ognian