Resolution of relative $ref with fragment

[cschramm]

Follow up to #432 (comment) (Sorry, it was not #640 and unfortunately 0.28.1 / #665 does not fix it)

A relative $ref with a fragment like other.json#/$defs/obj1 fails to resolve.

Due to 4b34b75#diff-fd99d42493bf63977b4e2c0b1a10fdcef8528f837daee1a504d68d0b24186cf5L455-R475, the retriever gets passed json-schema:///other.json instead of other.json resolved against the $id of the containing schema.

The if branch added in that change might have just been a workaround for references starting with a fragment that #665 now handled in resolve_against so that it's probably obsolete. It seems harmful for references not starting with a fragment, but containing one. I do not really understand why DEFAULT_ROOT_URI would ever be used over a present base.

[Stranger6667]

Could you, please, share an example of such a schema? It would help me a lot with fixing the issue

[cschramm]

Well, trying to prepare a minimal example got me completely confused now. The issue seems to depend on some execution order or something and is not as general as expected.

Having a /tmp/schemas/one.json with

{
  "$defs": {
    "obj": {
      "$ref": "other.json#/$defs/obj"
    }
  }
}

and running

jsonschema::validator_for(&json!({
    "$id": "file:///tmp/schemas/root.json",
    "$ref": "one.json#/$defs/obj"
}))
.unwrap();

There seems to be a 50:50 chance to get

ValidationError { instance: Null, kind: Referencing(Unretrievable { uri: "json-schema:///other.json", source: "Unknown scheme json-schema" }), instance_path: Location(""), schema_path: Location("") }

or

ValidationError { instance: Null, kind: Referencing(Unretrievable { uri: "file:///tmp/schemas/other.json", source: Os { code: 2, kind: NotFound, message: "No such file or directory" } }), instance_path: Location(""), schema_path: Location("") }

(as I do not have that file)

[cschramm]

Ok, forget the confusion. In any case external at

jsonschema/crates/jsonschema-referencing/src/registry.rs

Line 407 in 29b37f0

for uri in external.drain() {

contains both json-schema:///other.json#/$defs/obj and file:///tmp/schemas/other.json#/$defs/obj. The error just depends on their order and when I add a /tmp/schemas/other.json with e.g.

{
  "$defs": {
    "obj": {
      "type": "number"
    }
  }
}

I always get the Unknown scheme json-schema error.