How to specify a schema where an object can be any key-value combination

[simaotwx]

I want the LLM to generate a JSON like this

{
  "name": "John Doe",
  "info": {
    "age": "41",
    "tennis_club": "Detroit Club",
    "wife": "Jan Doe",
  }
}

The info is not always the same. Some people might not have a wife so the property would be omitted.
In theory, there could be thousands of combinations in the "info".

If I specify a schema like this:

{
    "type": "object",
    "properties": {
        "name": { "type": "string" },
        "info": {
            "type": "object"
        }
    }
}

It would error with:

  File "venv/lib/python3.11/site-packages/jsonformer/main.py", line 185, in generate_value
    return self.generate_object(schema["properties"], new_obj)
                                ~~~~~~^^^^^^^^^^^^^^
KeyError: 'properties'

So "properties" is required.

The only way I currently see to solve this is to use an array with objects of format {"key": "...", "value": "..."}

So the schema would look like:

{
    "type": "object",
    "properties": {
        "name": { "type": "string" },
        "info": {
            "type": "array",
            "items": {
                "type": "object",
                "properties": {
                    "key": { "type": "string" },
                    "value": { "type": "string" }
               }
           }
        }
    }
}

But I'd rather avoid this.