field checker test

fielder.go

@@ -149,7 +149,7 @@ func fieldVal(val reflect.Value, fieldName string, files RequestFiles, names ...
 			}
 			if !field.IsValid() {
 				log.Println("invalid")
-				log.Printf("%T\n", val)
+				log.Printf("%T\n", val.Interface())
 				if f, check := val.Interface().(IFieldChecker); check {
 					log.Println("ifieldchecker")
 					if check := f.RestFieldCheck(fieldName); check {