Draft 7 with errors

[ar45]

This allows one to use and resolve ids in json schema

SELECT json_schema_resolve_refs('{
                "$id": "http://localhost:1234/root",
                "allOf": [{
                    "$ref": "http://localhost:1234/nested.json#foo"
                }],
                "definitions": {
                    "A": {
                        "$id": "nested.json",
                        "definitions": {
                            "B": {
                                "$id": "#foo",
                                "type": "integer"
                            }
                        }
                    }
                }
            }'
     );

Resolves to

{
  "$id": "http://localhost:1234/root",
  "allOf": [
    {
      "$ref": "http://localhost:1234/nested.json#foo",
      "$_resolvedRef": [
        "definitions",
        "A",
        "definitions",
        "B"
      ]
    }
  ],
  "definitions": {
    "A": {
      "$id": "nested.json",
      "definitions": {
        "B": {
          "$id": "#foo",
          "type": "integer"
        }
      }
    }
  }
}

SELECT validate_json_schema(
    json_schema_resolve_refs('{
                "$id": "http://localhost:1234/root",
                "allOf": [{
                    "$ref": "http://localhost:1234/nested.json#foo"
                }],
                "definitions": {
                    "A": {
                        "$id": "nested.json",
                        "definitions": {
                            "B": {
                                "$id": "#foo",
                                "type": "integer"
                            }
                        }
                    }
                }
            }'
     )
);