JSON Schema oneOf validation - json

Question

I'm trying to create a JSON Schema that will allow a property to be either a number or an object of a specific format.
My data looks like this:
{
"num": 200
}
and my Schema looks like this:
{
"properties": {
"num": {
"type": [
"number",
"object"
],
"oneOf": [
{
"type": "number"
},
{
"$ref": "#/definitions/Variable"
}
]
}
},
"required": [
"num"
],
"additionalProperties": false,
"definitions": {
"Variable": {
"title": "Variable",
"properties": {
"$variable$": {
"type": "boolean",
"example": true
},
"name": {
"type": "string"
},
"defaultValue": {
"type": [
"string",
"object",
"number"
]
}
},
"required": [
"$variable$",
"name"
],
"additionalProperties": false
}
}
}
When I run it via a validator here: https://www.jsonschemavalidator.net/
I get this error:
Message: JSON is valid against more than one schema from 'oneOf'. Valid schema indexes: 0, 1.
Schema path: #/properties/num/oneOf
I'm assuming I'm missing something obvious about how oneOf works, but I can't figure out what it might me. Would appreciate any help here, thanks!

Answer 1

The error you are getting is telling you that both of you oneOf schemas are validating as true. It might be surprising that the value 4 is valid against the following schema.
{
"properties": {
"foo": { "type": "string": }
},
"required": ["foo"]
}
It turns out that the properties keyword and the required keyword don't apply when the value is not an object. So, the above schema is effectively the empty schema ({}) when validating against a number (or anything that is not an object). Because the empty schema means there are no constraints, everything is valid.
To fix your problem just add "type": "object" to your /definitions/Variable schema.

Answer 2

For your case you don't need oneOf at all, you can simply use
"type": ["number",{"$ref":"#/definitions/Variable"}] instead of "type": ["number","object"]
{
"properties": {
"num": {
"type": [
"number",{"$ref":"#/definitions/Variable"}
]
}
},
"required": [
"num"
],
"additionalProperties": false,
"definitions": {
"Variable": {
"title": "Variable",
"properties": {
"$variable$": {
"type": "boolean",
"example": true
},
"name": {
"type": "string"
},
"defaultValue": {
"type": [
"string",
"object",
"number"
]
}
},
"required": [
"$variable$",
"name"
],
"additionalProperties": false
}
}
}