Better error messages when oneOf/anyOf doesn't match

[skilledDeveloper]

Consider this example:

var schema = {
    "type": "object",
    "required": ["foo", "bar"],
    "additionalProperties": false,
    "properties": {
        "foo": {
            "type": "integer"
        },
        "bar": {
            "oneOf": [{
                "type": "object",
                "required": ["id"],
                "additionalProperties": false,
                "properties": {
                    "id": {
                        "type": "integer"
                    }
                }
            }, {
                "type": null,
                "additionalProperties": false
            }]
        }
    }
};

var candidate = {
    "foo": 123,
    "bar": {
        "id": 456
    }
};

Based on the schema the candidate is valid. However, if I change the id to a string value (e.g "456"), I will get this error:

[ { field: 'data.bar',
    message: 'no (or more than one) schemas match' } ]

While the error message is not wrong, it can be more informative by saying which field has issue.
The same thing can apply for missing required fields or having additional properties when it's not allowed.

[danieljuhl]

Are you using the latest version? Additional properties and required fields should be very informative, if you use the verbose mode.

How do you think the error message for the above example should be?

[skilledDeveloper]

Doesn't really matter. Maybe the same way that it works for the required fields?
Or probably something like this:

[ { field: 'data.bar',
    message: 'no (or more than one) schemas match:  
         field: 'bar.id' 
         message: 'is the wrong type'} ]

[mafintosh]

@skilledDeveloper would something like the following work:

{
  field: 'data.bar.id',
  schema: 'data.bar#anyOf[1]',
  message: 'is the wrong type'
}

Then we could add a schema identifier to subschemas as well to solve stuff like #22 as well

[skilledDeveloper]

That would be great.

[adrai]

any news?

[watson]

@mafintosh I think a schema property would be a nice addition. First I thought it would be nicer if we could fix it without adding extra properties, but we add extra properties already when in verbose mode - so I guess it's ok :)

I don't know if there is a convention for naming these "anonymous" inline schemas, but I think your data.bar#oneOf[1] suggestion is pretty self explanatory.

When using $ref, I guess the schema value would just be the name of the external schema.

[adrai]

+1