Array items reference problem

[odise]

Hi,

updated jsonschema to 1.1.0 today and now I'm facing the following problem. Given is a simple schema like this:

{
    "type": "object",
    "$schema": "http://json-schema.org/draft-03/schema",
    "id": "#",
    "required": false,
    "properties": {
        "record_object": {
            "type": "object",
            "id": "record",
            "properties": {
                "mimetype": {
                    "type": "string"
                 }
            }
        },
        "event_object": {
            "type": "object",
            "id": "event",
            "properties": {
                "actions": {
                    "type": "array",
                    "id": "actions",
                    "items": {
                        "type": "object",
                        "$ref": "#/properties/record_object"
                    }
                }
            }
        } 
    }
}

Trying to validate the following JSON (or any other) raises an exception:

event = { "event_object": {
    "actions": [
        { 
            "mimetype": "test"
        }
    ]
}}

validate(event, schema)

 Traceback (most recent call last):
  File "gsa_schema.py", line 120, in <module>
    validate(event, s) 
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 1301, in validate
    cls(schema, *args, **kwargs).validate(instance)
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 226, in validate
    for error in self.iter_errors(*args, **kwargs):
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 219, in iter_errors
    for error in errors:
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 436, in validate_properties
    for error in self.iter_errors(instance[property], subschema):
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 219, in iter_errors
    for error in errors:
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 436, in validate_properties
    for error in self.iter_errors(instance[property], subschema):
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 219, in iter_errors
    for error in errors:
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 268, in validate_items
    for error in self.iter_errors(item, items):
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 219, in iter_errors
    for error in errors:
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 403, in validate_ref
    with self.resolver.resolving(ref) as resolved:
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 1026, in resolving
    document = self.resolve_remote(uri)
  File "/Users/jan/Documents/code/jira/lib/python2.7/site-packages/jsonschema.py", line 1099, in resolve_remote
    result = json.loads(urlopen(uri).read().decode("utf-8"))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 126, in urlopen
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 386, in open
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib2.py", line 248, in get_type
ValueError: unknown url type: actions

In case I do something wrong here please point me to it. Thanks in advance.
Jan

[gazpachoking]

The 'id' keyword changes the resolution scope of $refs. Your ref becomes actions#/properties/record_object. Perhaps we should be wrapping that in a RefResolutionError though.

[odise]

Alright. removing all id properties helps.

[Julian]

Yes, that'd do this. We can leave this open so that there's a better error message if you do this, but yeah, the id property is defined by JSON Schema, you can't use it for your own purposes (and expect things to work :D). If you want something like what it looks like you're using it for, there's title and description.

[odise]

I don't use it at all to tell the truth. I think it came in while creating an initial schema via http://www.jsonschema.net/#. Simply removing it fixed my problem ;). Thanks a lot!

[Julian]

Ouch. I see. I'll send over an email to the author. I'm reopening just so we can change this to a RefResolutionError.

[gazpachoking]

Should we add a cause attribute to RefResolutionError to attach the original exception? What should the message for the RefResolutionError be in these cases?

[gazpachoking]

Also, it seems like we might want some other attributes on the RefResolutionError, at least one that has the ref which caused the error.

[Julian]

Resolution errors are errors, they're not really things that are expected to happen and to be queried at runtime like ValidationErrors.

So I don't think any sort of information is necessary on them other than a message appropriate for each possible time one can happen that the developer can decypher to see what they did wrong.