Adam Matan Adam Matan - 6 months ago 30
Python Question

JSON Schema: validate a number-or-null value

Is there a way to enable a JSON schema property to be either a number or


I am building an API which contains a
attribute. Can be a number between 0 (inclusive) and 360 (exclusive), or null, so the following inputs are OK:

{"heading": 5}
{"heading": 0}
{"heading": null}
{"heading": 12}
{"heading": 120}
{"heading": null}

And the following inputs are erroneous:

{"heading": 360}
{"heading": 360.1}
{"heading": -5}
{"heading": false}
{"heading": "X"}
{"heading": 1200}
{"heading": false}


is clearly the right answer. Adding the full schema for clarity.


"$schema": "",
"type": "object",
"additionalProperties": false,
"properties": {
"heading": {
"anyOf": [
{"type": "number"},
{"type": "null"}


In draft-04, you would use the anyOf directive:

  "anyOf": [
      "type": "number",
      "minimum": 0,
      "maximum": 360,
      "exclusiveMaximum": true
      "type": "null"

You could also use "type": ["number", "null"] as Adam suggests, but I think anyOf is cleaner (as long as you use a draft-04 implementation), and ties the minimum and maximum declaration to the number explicitly.

Disclaimer: I don't know anything about the python implementation, my answer is about json schema.