public static string GetExpressionString(Record rec, string propertyName)
 {
     var result = GetValueFuncFromRecord.Invoke(rec, propertyName, null);
     return result;
 }
 public static string GetExpressionString(Record rec, string propertyName, object defaultValue)
 {
     var defValue = defaultValue != null ? defaultValue.ToString() : null;
     var result = GetValueFuncFromRecord.Invoke(rec, propertyName, defValue);
     return result;
 }