Feature Request: not schema

[alturkovic]

Support not schema: https://json-schema.org/understanding-json-schema/reference/combining#not

[alturkovic]

For an example, generate an odd number between 10-20:

{
  "type": "integer",
  "minimum": 10,
  "allOf": [
    {
      "maximum": 20
    }
  ],
  "not": {
    "allOf": [
      {
        "multipleOf": 2
      }
    ]
  }
}

The example provided is deliberately more complex than it needs to be to show the composing nature of the problem.

[ghandic]

Do you have a proposed solution for this?

[alturkovic]

https://github.com/json-schema-faker/json-schema-faker/blob/d4403ae6cdba2206fe86399900c4095de8db7d2a/src/lib/core/utils.mjs#L350
https://github.com/json-schema-faker/json-schema-faker/blob/d4403ae6cdba2206fe86399900c4095de8db7d2a/src/lib/core/traverse.mjs#L64

It seems like the original author built a new schema and "manually" inversed some of the properties and then replaced the original schema...
For an example, it does not handle multipleOf that I mentioned originally.
I suppose that was meant to be handled in the TODO section lower in the linked method, but I do not think that it is possible for multipleOf since that should be evaluated in the value generator itself since there is no way to "inverse" it (if I am not mistaken?).

Another approach might be to collect all the constraints imposed on a certain value and then generate a value matching all those constraints?
For an example:

• type must be integer
• value must be in range 10 .. 20
• must not be divisible by 2

But I assume that could get very complicated very fast with lots of constraints...

[alturkovic]

I think that the problem is much bigger than I initially assumed:

jsf/jsf/parser.py

Line 255 in 8db0755

def __parse_definition(

The current implementation will only take type into consideration if it encounters that keyword, so valid definitions such as the one below will not work:

{
  "type": "integer",
  "allOf": [
    {
      "minimum": 10
    },
    {
      "maximum": 20
    }
  ]
}

The above should be equivalent to:

{
  "type": "integer",
  "minimum": 10,
  "maximum": 20
}

I think the __parse_definition needs to do some more sofisticated "merging" than it currently does. Unfortunately, I do not know Python to jump in with any PRs...

[ghandic]

I would have thought the above wouldn't be valid without a type in the all of objects.

[alturkovic]

Yup, that was my assumption also at first, but things are a bit more complicated...
I have tested the schema above with the original JSF and here. Seems to be valid.