JSON schema : “allof” with “additionalProperties”

Question

Suppose we have schema following schema (from tutorial here):

{
  \"$schema\": \"http://json-schema.org/draft-04/schema#\",

  \"definitions\": {
    \"addr         


        

Answer 1

Here's a slightly simplified version of Yves-M's Solution:

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "definitions": {
    "address": {
      "type": "object",
      "properties": {
        "street_address": {
          "type": "string"
        },
        "city": {
          "type": "string"
        },
        "state": {
          "type": "string"
        }
      },
      "required": [
        "street_address",
        "city",
        "state"
      ]
    }
  },
  "type": "object",
  "properties": {
    "billing_address": {
      "$ref": "#/definitions/address"
    },
    "shipping_address": {
      "allOf": [
        {
          "$ref": "#/definitions/address"
        }
      ],
      "properties": {
        "type": {
          "enum": [
            "residential",
            "business"
          ]
        },
        "street_address": {},
        "city": {},
        "state": {}
      },
      "required": [
        "type"
      ],
      "additionalProperties": false
    }
  }
}

This preserves the validation of required properties in the base address schema, and just adds the required type property in the shipping_address.

It's unfortunate that additionalProperties only takes the immediate, sibling-level properties into account. Maybe there is a reason for this. But this is why we need to repeat the inherited properties.

Here, we're repeating the inherited properties in simplified form, using empty object syntax. This means that properties with these names would be valid no matter what kind of value they contained. But we can rely on the allOf keyword to enforce the type constraints (and any other constraints) declared in the base address schema.