YYYY-M-D is incorrectly allowed as a format for dates

[DJTommek]

Hi,
I'm struggling with validating "date" type. According to specifications it should be in format YYYY-MM-DD (4 digits - 2 digits - 2 digits) but this jsonschema validator is ok with YYYY-M-D.

Example schema snippet:

"d": {
    "type": "string",
    "format": "date"
}

If I test it in https://www.jsonschemavalidator.net/ it properly throws error: String '2000-1-01' does not validate against format 'date'.

I don't think that is expected behaviour.

See live demo here: https://repl.it/@TomasPalider/QueasyDrabServerapplication

I came up with workaround by combination date and regex but I don't like it since schema validation should be strict.

"d": {
    "type": "string",
    "format": "date",
    "pattern": "^[0-9]{4}-[0-9]{2}-[0-9]{2}$"
}

[Julian]

Sounds like a bug if so. An upstream test case would be appreciated in the upstream test suite (and of course a PR even more appreciated).

[helrond]

I am experiencing this issue too, which I believe is occurring because strptime will parse dates which do not have zero-padded months or days.

I've added a PR to the upstream validation library.

I'd also be happy to submit a PR here. As I see it there are two options for replacing the current strptime implementation:

• Use the built-in fromisoformat() method on datetime.date. The drawback for this is that i t only works on Python 3.7+.
• Use a regex check (as OP did)

Any preference?

[Julian]

Awesome! Thank you very much for filing the upstream PR (I saw you already got a review there but yeah you're on the right track).

On implementation... I suppose fromisoformat is the better option, and that on 3.6 we fall back to the current (buggy) behavior.