firstSample.json

{
    "input": {
        "rating": {
            "primary": {
                "value": 4,
                "max": 5
            },
            "quality": {
                "value": 3,
                "max": 7
            }
        }
    },

    "spec": {
        "rating": {
            "primary": {
                "value": "Rating",  // simple match.  Put the value '4' in the output under the "Rating" field
                "max": "RatingRange"
            },

            // match any children of "rating".
            // Shiftr has a precendence order when matching, so the "*" will match anything that isn't "primary"
            "*": {
                "value": "SecondaryRatings.&1.Value", // &1 means, go up one level and grab that value and substitute it in
                "max": "SecondaryRatings.&1.Range",   //  in this example &1 = "quality"

                "$": "SecondaryRatings.&1.Id"
                // we want "quality" to be a value field in the output under
                //  "SecondaryRatings.quality.Id", but "quality" is an input key not an input value.
                // The "$" operator means use the input key, instead of the input value, to place in the output
            }
        }
    },

    "expected": {
        "Rating": 4,
        "RatingRange": 5,
        "SecondaryRatings": {
            "quality": {          // created by the '"value": "SecondaryRatings.&1.Value"' or "max": "SecondaryRatings.&1.Range" lines
                "Id": "quality",  // created by the '"$": "SecondaryRatings.&1.Id"' from the spec
                "Value": 3,
                "Range": 7
            }
        }
    }
}