patternProperties & properties

[gantsevdenis]

So I am implementing a Draft04 validator for fun, and running it against test suite https://github.com/json-schema-org/JSON-Schema-Test-Suite.

When reading the algorithm given in the "Example" section of "additionalProperties, properties and patternProperties" (
https://json-schema.org/draft-04/draft-fge-json-schema-validation-00#rfc.section.5.4.4), we have this sentence:

Having collected these three sets, the process is as follows:
    remove from "s" all elements of "p", if any;
    for each regex in "pp", remove all elements of "s" which this regex matches.

However, the above mentionned test suit actually tells me otherwise. Given:

"schema": {
            "properties": {
                "foo": {"type": "array", "maxItems": 3},
                "bar": {"type": "array"}
            },
            "patternProperties": {"f.o": {"minItems": 2}},
            "additionalProperties": {"type": "integer"}
        }
...
"data": {"foo": []},

We have:

s = ["foo"]
p = ["foo", "bar"]
pp = ["f.o"]

Then:

- remove from "s" all elements of "p", if any
s = [] // "foo" was removed

- for each regex in "pp", remove all elements of "s" which this regex matches
s is empty, so nothing applies

So in my understanding, the above instance should validate, but according to tests, it doesn't. Can someone please explain this?

[gregsdennis]

In this case, additionalProperties doesn't enter into the validation at all, really.

The validation is failing because it matches the patternProperties, which says the array at /foo needs to have a minimum of 2 elements, but it has none.

[gantsevdenis]

Okey so because additionalProperties doesn't have boolean value 'false' , the whole algorithm described above doesn't even apply. Correct?

[gregsdennis]

It's not about the subschema of additionalProperties in this case because all properties are handled by properties and patternProperties.

additionalProperties only handles properties that aren't handled by the other two. Since foo is handled by both, additionalProperties ignores it.

This validation would fail even if additionalProperties was removed from the schema.

[gantsevdenis]

Okey thanks, that makes pass all the related tests cases :)