lower case all struct's string fields in Go

struct_utils.go

// LowerStruct changes to lower case all struct's string fields                                                                                                                                           
// of the passed struct.                                                                                                                                                                   
func LowerStruct(strPtr interface{}) error {                                                                                                                                               
        str := reflect.ValueOf(strPtr)                                                                                                                                                     
        if str.Kind() != reflect.Ptr {                                                                                                                                                     
                return errors.New("pointer to struct expected")                                                                                                                            
        }                                                                                                                                                                                  
        v := str.Elem()                                                                                                                                                                    
        for i := 0; i < v.NumField(); i++ {                                                                                                                                                
                fieldValue := v.Field(i)                                                                                                                                                   
                if fieldValue.CanSet() && fieldValue.Kind() == reflect.String {                                                                                                            
                        s := fieldValue.String()                                                                                                                                           
                        fieldValue.SetString(strings.ToLower(s))                                                                                                                           
                }                                                                                                                                                                          
        }                                                                                                                                                                                  
        return nil                                                                                                                                                                         
}