`additionalProperties` rule in JSON schema is not applied to nested level properties

Question

So I have a JSON schema with additionalProperties rule set to false like.

{
  "type": "object",
  "properties": {
    "metadata": {
      "type": "object",
      "properties": {
        "a": {
          "type": "string"
        },
        "b": {
          "type": "string"
        },
        "c": {
          "type": "string"
        }
      }
    },
    "street_type": {
      "type": "string",
      "enum": [
        "Street",
        "Avenue",
        "Boulevard"
      ]
    }
  },
  "additionalProperties": false
}

and a payload like

{
  "metadata": {
    "a": "aa",
    "b": "bb",
    "c": "cc",
    "d": "dd"
  }
}

Should I expect my JSON schema parser/validator to pass the validation, the JSON schema parser I am using com.github.fge.jsonschema.main.JsonSchema passes validation though metadata/d is not present in the schema with additionalProperties set to false ,

This is very misleading, can someone direct me in the correct direction.

Is the additionalProperties JSON schema definition only applies to top-level fields and not to any nested level fields?

Answer 1

Is the additionalProperties JSON schema definition only applies to top-level fields and not to any nested level fields?

No you should be able to put it at whichever level you need as long as it is in a schema describing an object. In your case you simply put it at the wrong place. This should work:

{
  "type": "object",
  "properties": {
    "metadata": {
      "type": "object",
      "properties": {
        "a": {
          "type": "string"
        },
        "b": {
          "type": "string"
        },
        "c": {
          "type": "string"
        }
      },
      "additionalProperties": false
    },
    "street_type": {
      "type": "string",
      "enum": [
        "Street",
        "Avenue",
        "Boulevard"
      ]
    }
  }
}

Let say that you wanted to validate the following object as is:

{
  a: {
    b: {
      c: {
        d: 42
      }
    }
  }
}

One valid schema for it would be:

{
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "a": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "b": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "c": {
              "type": "object",
              "additionalProperties": false,
              "properties": {
                "d": {
                  "const": 42
                }
              }
            }
          }
        }
      }
    }
  }
}

The schema above is extremely verbose but is here for illustration purpose. You should be able to make it a bit more succinct by using $ref and combining schemas together.