jsonschema.exceptions.SchemaError: 'maximum' is a dependency of 'exclusiveMaximum'

Question

I get a metaschema validation error when using python's jsonschema module. Try running this code to replicate:

import json
from jsonschema import validate

myschema = """
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "type": "object",
  "properties": {
    "borderFrac": {
      "type": "number",
      "exclusiveMinimum": 0.0,
      "exclusiveMaximum": 0.5
    }
  }
}
"""

validate({"borderFrac": 0.4}, schema=json.loads(myschema))

This is the error I get:

jsonschema.exceptions.SchemaError: 'maximum' is a dependency of 'exclusiveMaximum'

Why?

Answer 1

It's throwing that error because "exclusiveMinimum" and "exclusiveMaximum" changed behaviour in between schema versions "draft-04" and "2020-12":

In JSON Schema Draft 4, exclusiveMinimum and exclusiveMaximum work differently. There they are boolean values, that indicate whether minimum and maximum are exclusive of the value. For example:

• if exclusiveMinimum is false, x ? minimum.
• if exclusiveMinimum is true, x > minimum. This was changed to have better keyword independence.

Fix: Therefore we should update the "$schema" to the latest one:

...
"$schema": "https://json-schema.org/drafts/2020-12/schema",
...

Note that it's actually a substantial number of versions since draft 04, which was released in 2013-01.