NullableImageUrl: introduce the interface for zeroing image url field.

Required for adding a field for specifying image URL later.

No functional changes.

Author: php-coder

src/main/java/ru/mystamps/web/controller/SeriesController.java

@@ -63,6 +63,7 @@
 import ru.mystamps.web.controller.dto.AddImageForm;
 import ru.mystamps.web.controller.dto.AddSeriesForm;
 import ru.mystamps.web.controller.dto.AddSeriesSalesForm;
+import ru.mystamps.web.controller.dto.NullableImageUrl;
 import ru.mystamps.web.controller.interceptor.DownloadImageInterceptor;
 import ru.mystamps.web.dao.dto.EntityWithIdDto;
 import ru.mystamps.web.dao.dto.LinkEntityDto;
@@ -499,7 +500,7 @@ private void addSeriesSalesFormToModel(Model model) {
 	}
 
 	private static void loadErrorsFromDownloadInterceptor(
-		AddSeriesForm form,
+		NullableImageUrl form,
 		BindingResult result,
 		HttpServletRequest request) {
 
@@ -525,7 +526,7 @@ private static void loadErrorsFromDownloadInterceptor(
 						"image",
 						"ru.mystamps.web.support.beanvalidation.NotEmptyFilename.message"
 					);
-					form.setImageUrl(null);
+					form.nullifyImageUrl();
 					break;
 				default:
 					result.rejectValue(

src/main/java/ru/mystamps/web/controller/dto/AddSeriesForm.java

@@ -75,7 +75,7 @@
 	)
 })
 @ReleaseDateIsNotInFuture(groups = AddSeriesForm.ReleaseDate3Checks.class)
-public class AddSeriesForm implements AddSeriesDto, HasImageOrImageUrl {
+public class AddSeriesForm implements AddSeriesDto, HasImageOrImageUrl, NullableImageUrl {
 
 	// FIXME: change type to plain Integer
 	@NotNull

src/main/java/ru/mystamps/web/controller/dto/NullableImageUrl.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2009-2017 Slava Semushin <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+package ru.mystamps.web.controller.dto;
+
+/**
+ * Interface of the form that has image URL field and supports its zeroed.
+ */
+public interface NullableImageUrl {
+	void setImageUrl(String url);
+	
+	default void nullifyImageUrl() {
+		setImageUrl(null);
+	}
+}