ZK-4970: listbox renders empty

zktest/src/archive/test2/B-ZK-4970.zul

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+B4970.zul
+
+	Purpose:
+
+	Description:
+
+	History:
+		Fri Jul 23 10:38:57 CST 2021, Created by rudyhuang
+
+Copyright (C) 2021 Potix Corporation. All Rights Reserved.
+
+-->
+<zk>
+    <label multiline="true">
+        1. Click the button.
+        2. You should see a Listbox with some data.
+    </label>
+    <div apply="org.zkoss.zktest.test2.B4970Composer"/>
+</zk>

zktest/src/org/zkoss/zktest/test2/B4970Composer.java

@@ -0,0 +1,52 @@
+/* B4970Composer.java
+
+	Purpose:
+
+	Description:
+
+	History:
+		Fri Jul 23 10:39:38 CST 2021, Created by rudyhuang
+
+Copyright (C) 2021 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.test2;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.zkoss.zk.ui.Executions;
+import org.zkoss.zk.ui.event.Events;
+import org.zkoss.zk.ui.util.Composer;
+import org.zkoss.zul.Button;
+import org.zkoss.zul.Div;
+import org.zkoss.zul.ListModelList;
+import org.zkoss.zul.Listbox;
+import org.zkoss.zul.ListitemRenderer;
+
+/**
+ * @author rudyhuang
+ */
+public class B4970Composer implements Composer<Div> {
+	private Div div;
+
+	@Override
+	public void doAfterCompose(Div comp) throws Exception {
+
+		Button button = new Button("create");
+		comp.appendChild(button);
+
+		button.addEventListener("onClick", event -> {
+			div = (Div) Executions.createComponentsDirectly(
+					"<div apply='${arg.innerComposer}'><listbox/></div>", "zul",
+					null,
+					Collections.singletonMap("innerComposer", (Composer<Div>) div2 -> {
+						div2.addEventListener("onInitModel", event2 -> {
+							Listbox listbox = (Listbox) div2.getFirstChild();
+							listbox.setModel(new ListModelList<>(Arrays.asList("aaa", "bbb", "ccc")));
+							listbox.setItemRenderer((ListitemRenderer<String>) (item, data, index) -> item.setLabel(data));
+						});
+						Events.postEvent("onInitModel", div2, null);
+					}));
+		});
+	}
+}

zktest/test/java/org/zkoss/zktest/zats/test2/B_ZK_4970Test.java

@@ -0,0 +1,32 @@
+/* B_ZK_4970Test.java
+
+	Purpose:
+
+	Description:
+
+	History:
+		Fri Jul 23 10:59:52 CST 2021, Created by rudyhuang
+
+Copyright (C) 2021 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.zats.test2;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import org.zkoss.zktest.zats.WebDriverTestCase;
+
+/**
+ * @author rudyhuang
+ */
+public class B_ZK_4970Test extends WebDriverTestCase {
+	@Test
+	public void test() {
+		connect();
+
+		click(jq("@button"));
+		waitResponse();
+
+		Assert.assertEquals(3, jq("@listitem").length());
+	}
+}

zul/src/org/zkoss/zul/impl/ListboxDataLoader.java

@@ -178,6 +178,7 @@ else if (max < 0)
 	private void invalidateListitems() {
 		//Bug 3147518: avoid memory leak
 		//Also better performance (outer better than remove a lot)
+		if (!_listbox.isInitialized()) return;
 		final Execution execution = Executions.getCurrent();
 		final String uuid = _listbox.getUuid();
 		final boolean isDeferInitModel = execution != null && execution.getAttribute("zkoss.Listbox.deferInitModel_" + uuid) != null;