How to extent an object with 1 parameter in json-schema - jsonschema

Question

I wrote one JSON schema before, but now, as I am trying to make it a bit more advanced I get stuck.
(I am open to 'good practice' tips in the comments)
(Is the $id optional? should I remove it for simplicity in the example code?)
Goal:
I am trying to make a schema with an object definition (example_obj) that is recursively used. This object may only have 1 argument (or or and or value). But in the root of the json, I want to add 1 additional property.
json-schema
{
"definitions": {
"example_obj": {
"$id": "#/definitions/example_obj",
"type": "object",
"maxProperties": 1,
"properties": {
"or": {
"$id": "#/definitions/example_obj/properties/or",
"type": "array",
"items": {
"$id": "#/definitions/example_obj/properties/or/items",
"$ref": "#/definitions/example_obj"
}
},
"and": {
"$id": "#/definitions/example_obj/properties/and",
"type": "array",
"items": {
"$id": "#/definitions/example_obj/properties/and/items",
"$ref": "#/definitions/example_obj"
}
},
"value": {
"$id": "#/definitions/example_obj/properties/value",
"type": "string"
}
}
}
},
"type": "object",
"title": "The Root Schema",
"required": ["filter_version"],
"allOf": [
{
"$ref": "#/definitions/example_obj"
},
{
"properties": {
"filter_version": {
"$id": "#/properties/filter_version",
"type": "string",
"pattern": "^([0-9]+\\.[0-9]+)$"
}
}
}
]
}
json which I want to pass validation:
{
"filter_version": "1.0",
"or": [
{
"and": [
{
"value": "subject"
}
]
},
{
"or": [
{
"value": "another subject"
}
]
}
]
}
Issue:
When I try to extend example_obj for the root definition it seems to fail because the example_obj object does not allow more then 1 property by design.
In other words, it appears that every check for the number of argument that I add to example_obj is also performed on the additional property (i.e. filter_version).
Does anyone know where to place this check for 'exactly 1 argument' so that it is not evaluated on the root object?
Attempts:
I tried working with different ways of determining the requirements of example_obj, but with no success. Like with replacing "maxProperties": 1 with:
"oneOf": [
{
"required": [
"or"
]
},
{
"required": [
"and"
]
},
{
"required": [
"where"
]
},
{
"required": [
"where not"
]
}
],
Thanks in advance for any help!!
Checking my schema with the online schema validator.
(In the end I need to validate it in Python, in case it matters)

Answer 1

You can use oneOf instead of maxProperties to get around this.
{
"type": "object",
"properties": {
"filter_version": {
"type": "string",
"pattern": "^([0-9]+\\.[0-9]+)$"
}
},
"required": ["filter_version"],
"allOf": [{ "$ref": "#/definitions/example_obj" }],
"definitions": {
"example_obj": {
"type": "object",
"properties": {
"or": { "$ref": "#/definitions/example-obj-array" },
"and": { "$ref": "#/definitions/example-obj-array" },
"value": { "type": "string" }
},
"oneOf": [
{ "required": ["or"] },
{ "required": ["and"] },
{ "required": ["value"] }
]
},
"example-obj-array": {
"type": "array",
"items": { "$ref": "#/definitions/example_obj" }
}
}
}
P.S. You are using $id wrong. I know there is a tool out there that generates schemas like this and causes this confusion. The way $id is used here is a no-op. It doesn't hurt, but it doesn't do anything other than bloating your schema.