How is asserting None handled

[humbienri]

Given this requests response.json() (note the None instead of null):

    "version": "2.3.4",
    "result": "Multi-Status",
    "data": [
        {
            "derId": 583,
            "warnings": [],
            "status": "success",
            "error": None
        }
    ]
}

why is it that this schema isn't sufficient:

    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "",
    "description": "JSON schema for the HTTP REST API response.",
    "type": "object",
    "properties": {
        "version": {"type": "string"},
        "result": {"type": "string"},
        "data": {
            "type": "array",
            "items": {
                "type": "object",
                "properties": {
                    "derId": {"type": "integer"},
                    "warnings": {"type": "array"},
                    "status": {"type": "string"},
                    "error": {"type": ["null","string"]}
                },
                "required": ["derId", "status", "warnings", "error"]
            }
        }
    },
    "required": ["data", "result", "version"]
}

Even if I remove the requirement for the error property, jsonschema.validate() chokes on the presence of None.

I realize that None is a python thing and not valid json, as I understand it, but it is the calling of the .json() api on the API's response that introduces the None.

Thank you in advance.

[Julian]

Hi, please include a full reproducer (the code you're running + its traceback).

Note though that, presuming you're talking about requests, that requests.Response.json does not return JSON, it returns Python objects, and that jsonschema.validate is expecting exactly that.

[humbienri]

Hello,
Sorry Julian, I did not include my actual code b/c it would get a bit tricky since my code is spread out across multiple modules and classes. I guess I could doctor up an actual example to trigger this rather than modifying my code for illustrative purposes.

But I do think you've hit the nail on the head. Yes I am using python's requests but seems like you are saying that *.json() does not output valid json?

One thing I did notice is that no matter how much I fiddled with my code I kept seeing an error regarding Assert None and instructed to use Assert is None. Your questions prompted me to try and reduce this down to just the commandline and try to reproduce this from there. So, import jsonschema and such and I was not able to reproduce the issue I was encountering. Can't believe I spend days on this and it was totally my fault.

I think somewhere along the way I forgot that the validate() returns None on a successful validation? So my assert valid_per_schema(blah dih dah) was essentially boiling down to assert None and it was pytest that was whining at me!!

Classic case of "we see what we want to see". Sheesh!

Thanks again @Julian! Sorry for the hassle.