asString function
Implementation
String asString(Map<String, dynamic>? json, String key, {String defaultValue = ""}) {
if (json == null || !json.containsKey(key)) return defaultValue;
var value = json[key];
if (value == null) return defaultValue;
if (value is String) return value;
if (value is int) return value.toString();
if (value is double) return value.toString();
if (value is bool) return value ? "true" : "false";
return defaultValue;
}