JSONSchema how to define a schema for a dynamic object

Question

I have a JSON response that I am trying to create a JSONSchema for

{
    "gauges": {
        "foo": {
            "value": 1234
        },
        "bar": {
            "value": 12.44
        }
    }
}

It is important to know that the objects in the associative array gauges are dynamically generated so there can be zero to many. Each object in gauges will always have a value property and it will always be a number.

So each these are valid

Example 1

{
    "gauges": {
        "foo": {
            "value": 1234
        }
    }
}

Example 2

{
    "gauges": {
        "dave": {
            "value": 0.44
        },
        "tommy": {
            "value": 12
        },
        "steve": {
            "value": 99999
        }
    }
}

Example 3

{
    "gauges": {}
}

I have looked though the specification and if this was an array I know I could use anyOf but I am unsure how to do this or if it is even possible.

NB I cannot change the format of the JSON

Answer 1

Conceptually what you want is an object representing a Typed Map.

The difficulty is that you have no named property to put your specification in the schema, but in that case You can use "additionalProperties"

{
"type": "object",
  "properties": {
    "gauges": {
      "type": "object",
      "additionalProperties": {
        "type": "object",
        "properties": {
           "value": {"type": "number"}
        }
      } 
    }
  }
}

"gauges" property is defined as an object in which every "additionalProperties" will have a type containing a value of type number.

Note: In java you would serialize it to a Map<String,Value> with Value the classe containing a value. (don't know for other typed language, but I am open to suggestions)

This answer point to an analog solution How to define JSON Schema for Map<String, Integer>?