JSON Schema $extends

gistfile1.js

// Abstract Shape Schema
{
    "id": "_Shape",
    "type": "object",

    "properties": {
        "x": {"type": "number"},
        "y": {"type": "number"}
    },
    "required": ["x", "y"]
}

// Circle Schema (extends Shape)
{
    "$extends": "/_Shape",
    "id": "Circle",
    "type": "object",

    "properties": {
        "radius": {"type": "number"}
    },
    "required": ["x", "y", "radius"]
}

// There is one problem: How to remove an unwanted inherited attribute?
{
    "$extends": "/_Shape",
    "id": "Circle",
    "type": "object",

    "properties": {
        "x": {} 
        // This keeps the property, but since it has no informations 
        // a validator could threat it like it would be non existing
    },
    "required": ["y", "radius"]
}