apache · jstuyts · Dec 4, 2025
diff --git a/...ests/src/test/java/org/apache/wicket/ajax/form/AjaxFormComponentUpdatingBehaviorTest.java b/...ests/src/test/java/org/apache/wicket/ajax/form/AjaxFormComponentUpdatingBehaviorTest.java
@@ -0,0 +1,87 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.wicket.ajax.form;
+
+import static java.lang.Boolean.TRUE;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.wicket.ajax.AjaxRequestHandler;
+import org.apache.wicket.ajax.AjaxRequestTarget;
+import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
+import org.apache.wicket.markup.Markup;
+import org.apache.wicket.markup.html.form.Form;
+import org.apache.wicket.markup.html.form.FormComponentPanel;
+import org.apache.wicket.markup.html.form.upload.MultiFileUploadField;
+import org.apache.wicket.model.Model;
+import org.apache.wicket.util.tester.WicketTestCase;
+import org.junit.jupiter.api.Test;
+
+class AjaxFormComponentUpdatingBehaviorTest extends WicketTestCase
+{
+    @Test
+    void enablesRecursiveSerializationIfComponentMarkedToWantToProcessInputOfChildrenInAjaxUpdate()
+    {
+        var behavior = new AjaxFormComponentUpdatingBehavior("some event")
+        {
+            @Override
+            protected void onUpdate(AjaxRequestTarget target)
+            {
+            }
+        };
+        var formComponentPanel = new MultiFileUploadField("someId");
+        formComponentPanel.setMetaData(FormComponentPanel.WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE, TRUE);
+        formComponentPanel.add(behavior);
+        var attributes = new AjaxRequestAttributes();
+
+        behavior.updateAjaxAttributes(attributes);
+
+        assertTrue(attributes.isSerializeRecursively());
+    }
+
+    @Test
+    void invokesProcessChildrenOnEventIfComponentMarkedToWantToProcessInputOfChildrenInAjaxUpdate()
+    {
+        var behavior = new AjaxFormComponentUpdatingBehavior("some event")
+        {
+            @Override
+            protected void onUpdate(AjaxRequestTarget target)
+            {
+            }
+        };
+        var form = new Form<Void>("form");
+        var hasProcessInputOfChildreenBeenCalled = new AtomicBoolean(false);
+        var formComponentPanel = new MultiFileUploadField("upload", Model.of(List.of()))
+        {
+            @Override
+            public void processInputOfChildren()
+            {
+                hasProcessInputOfChildreenBeenCalled.set(true);
+            }
+        };
+        formComponentPanel.setMetaData(FormComponentPanel.WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE, TRUE);
+        formComponentPanel.add(behavior);
+        form.add(formComponentPanel);
+        tester.startComponentInPage(form, Markup.of("<form wicket:id=\"form\"><input type=\"file\" wicket:id=\"upload\"></input></form>"));
+
+        behavior.onEvent(new AjaxRequestHandler(form.getPage()));
+
+        assertTrue(hasProcessInputOfChildreenBeenCalled.get());
+    }
+}
diff --git a/...che/wicket/markup/html/form/FormComponentPanelProcessingTest$InnerFormComponentPanel.html b/...che/wicket/markup/html/form/FormComponentPanelProcessingTest$InnerFormComponentPanel.html
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:wicket="http://wicket.apache.org">
+<body>
+<wicket:panel>
+</wicket:panel>
+</body>
+</html>
diff --git a/...che/wicket/markup/html/form/FormComponentPanelProcessingTest$OuterFormComponentPanel.html b/...che/wicket/markup/html/form/FormComponentPanelProcessingTest$OuterFormComponentPanel.html
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:wicket="http://wicket.apache.org">
+<body>
+<wicket:panel>
+<span wicket:id="inner"></span>
+</wicket:panel>
+</body>
+</html>
diff --git a/...ts/src/test/java/org/apache/wicket/markup/html/form/FormComponentPanelProcessingTest.java b/...ts/src/test/java/org/apache/wicket/markup/html/form/FormComponentPanelProcessingTest.java
@@ -16,13 +16,19 @@
  */
 package org.apache.wicket.markup.html.form;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import static java.lang.Boolean.TRUE;
+import static org.apache.wicket.markup.html.form.FormComponentPanel.WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import java.io.Serializable;
 
 import org.apache.wicket.MarkupContainer;
+import org.apache.wicket.ajax.AjaxRequestTarget;
+import org.apache.wicket.ajax.form.AjaxFormComponentUpdatingBehavior;
 import org.apache.wicket.markup.IMarkupResourceStreamProvider;
+import org.apache.wicket.markup.Markup;
 import org.apache.wicket.markup.html.WebPage;
 import org.apache.wicket.model.IModel;
 import org.apache.wicket.model.Model;
@@ -60,10 +66,56 @@ void clearInput()
 		tester.assertRenderedPage(TestPage.class);
 
 		TestFormComponentPanel fcp = (TestFormComponentPanel) tester.getComponentFromLastRenderedPage("form:panel");
-		assertEquals(false, fcp.isChildClearInputCalled());
+		assertFalse(fcp.isChildClearInputCalled());
 
 		fcp.clearInput();
-		assertEquals(true, fcp.isChildClearInputCalled());
+		assertTrue(fcp.isChildClearInputCalled());
+	}
+
+	@Test
+	void processInputOfChildAsksChildFormComponentPanelWithProcessingOfChildrenEnabledToProcessInputOnly()
+	{
+		var behavior = new AjaxFormComponentUpdatingBehavior("theEvent")
+		{
+			@Override
+			protected void onUpdate(AjaxRequestTarget target)
+			{
+			}
+		};
+		var form = new Form<Void>("form");
+		var outer = new OuterFormComponentPanel("outer", false);
+		outer.setMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE, TRUE);
+		outer.add(behavior);
+		form.add(outer);
+		tester.startComponentInPage(form, Markup.of("<form wicket:id=\"form\"><span wicket:id=\"outer\"></span></form>"));
+
+		tester.executeAjaxEvent(outer, "theEvent");
+
+		assertFalse(outer.inner.wasAskedToProcessInputOfChildren, "Inner must not be asked to process input of children");
+		assertTrue(outer.inner.wasAskedToProcessInput, "Inner must be asked to process input");
+	}
+
+	@Test
+	void processInputOfChildAsksChildFormComponentPanelWithProcessingOfChildrenEnabledToProcessChildrenAndInput()
+	{
+		var behavior = new AjaxFormComponentUpdatingBehavior("theEvent")
+		{
+			@Override
+			protected void onUpdate(AjaxRequestTarget target)
+			{
+			}
+		};
+		var form = new Form<Void>("form");
+		var outer = new OuterFormComponentPanel("outer", true);
+		outer.setMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE, TRUE);
+		outer.add(behavior);
+		form.add(outer);
+		tester.startComponentInPage(form, Markup.of("<form wicket:id=\"form\"><span wicket:id=\"outer\"></span></form>"));
+
+		tester.executeAjaxEvent(outer, "theEvent");
+
+		assertTrue(outer.inner.wasAskedToProcessInputOfChildren, "Inner must be asked to process input of children");
+		assertTrue(outer.inner.wasAskedToProcessInput, "Inner must be asked to process input");
 	}
 
 	private static class TestFormComponentPanel extends FormComponentPanel<Serializable>
@@ -79,7 +131,7 @@ private static class TestFormComponentPanel extends FormComponentPanel<Serializa
 		private TestFormComponentPanel(String id, IModel<Serializable> model)
 		{
 			super(id, model);
-			add(new TextField<Serializable>("text", new Model<>())
+			add(new TextField<>("text", new Model<>())
 			{
 				private static final long serialVersionUID = 1L;
 
@@ -106,7 +158,8 @@ public void clearInput()
 			});
 		}
 
-		private boolean isChildClearInputCalled() {
+		private boolean isChildClearInputCalled()
+		{
 			return childClearInputCalled;
 		}
 
@@ -169,4 +222,48 @@ public IResourceStream getMarkupResourceStream(MarkupContainer container,
 		}
 
 	}
+
+	private static class OuterFormComponentPanel extends FormComponentPanel<String>
+	{
+		public InnerFormComponentPanel inner = new InnerFormComponentPanel("inner");
+
+		public OuterFormComponentPanel(String id, boolean mustEnableProcessingOfChilderenInAjaxUpdateOfInner)
+		{
+			super(id, Model.of());
+
+			inner.setMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE, mustEnableProcessingOfChilderenInAjaxUpdateOfInner);
+			add(inner);
+		}
+
+		@Override
+		public void processInputOfChildren()
+		{
+			processInputOfChild(inner);
+		}
+	}
+
+	private static class InnerFormComponentPanel extends FormComponentPanel<String>
+	{
+		public boolean wasAskedToProcessInputOfChildren;
+		public boolean wasAskedToProcessInput;
+
+		public InnerFormComponentPanel(String id)
+		{
+			super(id, Model.of());
+		}
+
+		@Override
+		public void processInputOfChildren()
+		{
+			wasAskedToProcessInputOfChildren = true;
+		}
+
+		@Override
+		public void validate()
+		{
+			wasAskedToProcessInput = true;
+
+			super.validate();
+		}
+	}
 }
diff --git a/wicket-core/src/main/java/org/apache/wicket/ajax/form/AjaxFormComponentUpdatingBehavior.java b/wicket-core/src/main/java/org/apache/wicket/ajax/form/AjaxFormComponentUpdatingBehavior.java
@@ -16,6 +16,9 @@
  */
 package org.apache.wicket.ajax.form;
 
+import static java.lang.Boolean.TRUE;
+import static org.apache.wicket.markup.html.form.FormComponentPanel.WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE;
+
 import java.util.Locale;
 
 import org.apache.wicket.Application;
@@ -25,8 +28,8 @@
 import org.apache.wicket.ajax.AjaxRequestTarget;
 import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
 import org.apache.wicket.ajax.attributes.AjaxRequestAttributes.Method;
-import org.apache.wicket.core.request.handler.IPartialPageRequestHandler;
 import org.apache.wicket.markup.html.form.FormComponent;
+import org.apache.wicket.markup.html.form.FormComponentPanel;
 import org.apache.wicket.markup.html.form.validation.IFormValidator;
 import org.apache.wicket.util.lang.Args;
 import org.danekja.java.util.function.serializable.SerializableConsumer;
@@ -121,6 +124,12 @@ protected void updateAjaxAttributes(AjaxRequestAttributes attributes)
 		super.updateAjaxAttributes(attributes);
 
 		attributes.setMethod(Method.POST);
+
+		if (getComponent() instanceof FormComponentPanel<?> formComponentPanel
+				&& formComponentPanel.getMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE) == TRUE)
+		{
+			attributes.setSerializeRecursively(true);
+		}
 	}
 
 	@Override
@@ -135,6 +144,12 @@ protected final void onEvent(final AjaxRequestTarget target)
 
 		try
 		{
+			if (getComponent() instanceof FormComponentPanel<?> formComponentPanel
+					&& formComponentPanel.getMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE) == TRUE)
+			{
+				formComponentPanel.processInputOfChildren();
+			}
+
 			formComponent.inputChanged();
 			formComponent.validate();
 			if (formComponent.isValid())
@@ -199,7 +214,7 @@ protected boolean disableFocusOnBlur()
 	/**
 	 * Called to handle any error resulting from updating form component. Errors thrown from
 	 * {@link #onUpdate(org.apache.wicket.ajax.AjaxRequestTarget)} will not be caught here.
-	 *
+	 * <p>
 	 * The RuntimeException will be null if it was just a validation or conversion error of the
 	 * FormComponent
 	 *

diff --git a/wicket-core/src/main/java/org/apache/wicket/markup/html/form/FormComponentPanel.java b/wicket-core/src/main/java/org/apache/wicket/markup/html/form/FormComponentPanel.java
@@ -16,7 +16,10 @@
  */
 package org.apache.wicket.markup.html.form;
 
+import static java.lang.Boolean.TRUE;
+
 import org.apache.wicket.IQueueRegion;
+import org.apache.wicket.MetaDataKey;
 import org.apache.wicket.markup.ComponentTag;
 import org.apache.wicket.markup.html.panel.IMarkupSourcingStrategy;
 import org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy;
@@ -111,6 +114,34 @@
  */
 public abstract class FormComponentPanel<T> extends FormComponent<T> implements IQueueRegion
 {
+	/**
+	 * By setting this key to <code>true</code> (and implementing {@link #processInputOfChildren()}) it will be possible
+	 * to add a {@link org.apache.wicket.ajax.form.AjaxFormComponentUpdatingBehavior AjaxFormComponentUpdatingBehavior}
+	 * to this panel, and be able to access the updated model object of this panel in that behavior.
+	 * <p>
+	 * The panel must override {@link #processInputOfChildren()} and (should) call
+	 * {@link #processInputOfChild(FormComponent)} for each of its sub form components.
+	 * <p>
+	 * <code>AjaxFormComponentUpdatingBehavior</code> works for <code>FormComponentPanel</code>s that contain
+	 * {@link CheckBoxMultipleChoice}, {@link CheckGroup}, {@link RadioChoice} and/or {@link RadioGroup} fields. There
+	 * is no need to use
+	 * {@link org.apache.wicket.ajax.form.AjaxFormChoiceComponentUpdatingBehavior AjaxFormChoiceComponentUpdatingBehavior}.
+	 * <p>
+	 * The <code>AjaxFormComponentUpdatingBehavior</code> should use <code>"input change"</code> for the events in most
+	 * cases, so changes to all descendent form components will result in an Ajax update. <strong>Warning</strong>: some
+	 * form components will result in 2 events being emitted. For example, <code>&lt;input type="number"&gt;</code>.
+	 * <p>
+	 * <strong>Warning</strong>: some components may send excessive Ajax updates. Make sure the extra updates are not an
+	 * issue for your situation, or take steps to prevent them.
+	 * <p>
+	 * Note that the values of all form components of the panel will be submitted on each event, so use with panels with
+	 * possibly large values should probably be avoided.
+	 */
+	public static final MetaDataKey<Boolean> WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE = new MetaDataKey<>()
+	{
+		private static final long serialVersionUID = 1L;
+	};
+
 	private static final long serialVersionUID = 1L;
 
 	/**
@@ -165,11 +196,38 @@ public void clearInput()
 		super.clearInput();
 
 		// Visit all the (visible) form components and clear the input on each.
-		visitFormComponentsPostOrder(this, (IVisitor<FormComponent<?>, Void>) (formComponent, visit) -> {
+		visitFormComponentsPostOrder(this, (IVisitor<FormComponent<?>, Void>) (formComponent, visit) ->
+		{
 			if (formComponent != FormComponentPanel.this && formComponent.isVisibleInHierarchy())
 			{
 				formComponent.clearInput();
 			}
 		});
 	}
+
+	/**
+	 * Called by {@link org.apache.wicket.ajax.form.AjaxFormComponentUpdatingBehavior AjaxFormComponentUpdatingBehavior}
+	 * if {@link #WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE} is set to <code>true</code>. Each nested form component
+	 * must be asked to process its input. You should use {@link #processInputOfChild(FormComponent)} as this method
+	 * takes child <code>FormComponentPanel</code>s that also want their children to process the input into account.
+	 */
+	public void processInputOfChildren()
+	{
+	}
+
+	/**
+	 * Tell the given child component to process its input. If the child component is a <code>FormComponentPanel</code>
+	 * that wants its children to process their input, it will be told to do so.
+	 *
+	 * @param child the component that must be told to process its children.
+	 */
+	protected final void processInputOfChild(FormComponent<?> child)
+	{
+		if (child instanceof FormComponentPanel<?> formComponentPanel
+				&& formComponentPanel.getMetaData(WANT_CHILDREN_TO_PROCESS_INPUT_IN_AJAX_UPDATE) == TRUE)
+		{
+			formComponentPanel.processInputOfChildren();
+		}
+		child.processInput();
+	}
 }