How to merge two json schema without additional properties-CodePudding

I have two types defined by a JSON Schema:

Type A

{
  "type": "object",
  "properties": {
    "a": { "type": "string" }
  }
}

Type X

{
  "type": "object",
  "properties": {
    "x": { "type": "string" }
  }
}

I want to create a schema combining A and X, but without additional properties. (only properties 'a' and/or 'x' should be present). I tried to use "allOf" but I can't add a restriction about additional properties. If I add "additionalProperties" in A or X, it doesn't work.

How should I process ? Of course, I don't want to repeat A into X

CodePudding user response：

What you're looking for is the unevaluatedProperties feature available in jsonschema 2019-09 upwards. In contrast to additionalProperties, which only concerns the locally defined properties, unevaluatedProperties works across sub-schemas (but is more expensive to evaluate).

The schema

{
  "anyOf": [
    {
      "type": "object",
      "properties": {
        "a": {
          "type": "string"
        }
      }
    },
    {
      "type": "object",
      "properties": {
        "x": {
          "type": "string"
        }
      }
    }
  ],
  "unevaluatedProperties": false
}

Allows

{
    "a": "foo",
    "x": "bar"
}

But disallows

{
    "a": "foo",
    "x": "bar",
    "t": "baz"
}

If you're stuck with an earlier jsonschema version, you have to manually define the properties of the sub-schemas in the parent like this:

{
  "anyOf": [
    {
      "type": "object",
      "properties": {
        "a": {
          "type": "string"
        }
      }
    },
    {
      "type": "object",
      "properties": {
        "x": {
          "type": "string"
        }
      }
    }
  ],
  "properties": {
    "a": true,
    "x": true
  },
  "additionalProperties": false
}