How to replace field value when it equals "-"

[gbasic]

How to check if fields in "Data" are equal to "-" and if so change them to something else. This is my data (There are multiple cities in this JSON file with the same fields):

{
      "@version" => "1",
    "@timestamp" => 2020-09-08T13:14:29.058Z,
        "Europe" => {
        "DateTime" => {
            "Time" => "12",
             "Date" => "08.09.2020"
        },
               "City" => {
            "Data" => {
                        "Pressure" => "-",
                       "Humidity" => "83",
                        "cord" => {
                    "lat" => "52.37454030000001",
                    "lon" => "4.897975505617977"
                },
                 "WindDirection" => "SW",
                "WindSpeed" => "05",
                        "Temp" => "19"
            },
            "CityName" => "Amsterdam"
        }
    }
}