Improve caching when expanding nodes in hierarchical data (#8902)

Fixes #8790

2 files changed, 79 insertions, 0 deletions

diff --git a/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridBasicFeatures.java b/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridBasicFeatures.java
index 9b07cc106e..ae011355c9 100644
--- a/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridBasicFeatures.java
+++ b/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridBasicFeatures.java
@@ -3,13 +3,18 @@ package com.vaadin.tests.components.treegrid;
 import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
 
 import com.vaadin.annotations.Theme;
 import com.vaadin.annotations.Widgetset;
 import com.vaadin.data.HierarchyData;
 import com.vaadin.data.provider.DataProvider;
+import com.vaadin.data.provider.HierarchicalDataProvider;
+import com.vaadin.data.provider.HierarchicalQuery;
 import com.vaadin.data.provider.InMemoryHierarchicalDataProvider;
 import com.vaadin.server.SerializablePredicate;
+import com.vaadin.shared.Range;
 import com.vaadin.tests.components.AbstractComponentTest;
 import com.vaadin.ui.TreeGrid;
 
@@ -20,6 +25,7 @@ public class TreeGridBasicFeatures extends AbstractComponentTest<TreeGrid> {
     private TreeGrid<HierarchicalTestBean> grid;
     private InMemoryHierarchicalDataProvider<HierarchicalTestBean> inMemoryDataProvider;
     private LazyHierarchicalDataProvider lazyDataProvider;
+    private HierarchicalDataProvider<HierarchicalTestBean, ?> loggingDataProvider;
 
     @Override
     public TreeGrid getComponent() {
@@ -82,6 +88,26 @@ public class TreeGridBasicFeatures extends AbstractComponentTest<TreeGrid> {
 
         inMemoryDataProvider = new InMemoryHierarchicalDataProvider<>(data);
         lazyDataProvider = new LazyHierarchicalDataProvider(3, 2);
+        loggingDataProvider = new InMemoryHierarchicalDataProvider<HierarchicalTestBean>(
+                data) {
+
+            @Override
+            public Stream<HierarchicalTestBean> fetchChildren(
+                    HierarchicalQuery<HierarchicalTestBean, SerializablePredicate<HierarchicalTestBean>> query) {
+                Optional<HierarchicalTestBean> parentOptional = query
+                        .getParentOptional();
+                if (parentOptional.isPresent()) {
+                    log("Children request: " + parentOptional.get() + " ; "
+                            + Range.withLength(query.getOffset(),
+                                    query.getLimit()));
+                } else {
+                    log("Root node request: " + Range
+                            .withLength(query.getOffset(), query.getLimit()));
+                }
+                return super.fetchChildren(query);
+            }
+        };
+
     }
 
     @SuppressWarnings("unchecked")
@@ -90,6 +116,7 @@ public class TreeGridBasicFeatures extends AbstractComponentTest<TreeGrid> {
         LinkedHashMap<String, DataProvider> options = new LinkedHashMap<>();
         options.put("LazyHierarchicalDataProvider", lazyDataProvider);
         options.put("InMemoryHierarchicalDataProvider", inMemoryDataProvider);
+        options.put("LoggingDataProvider", loggingDataProvider);
 
         createSelectAction("Set data provider", CATEGORY_FEATURES, options,
                 "LazyHierarchicalDataProvider",
diff --git a/uitest/src/test/java/com/vaadin/tests/components/treegrid/TreeGridExpandDataRequestTest.java b/uitest/src/test/java/com/vaadin/tests/components/treegrid/TreeGridExpandDataRequestTest.java
new file mode 100644
index 0000000000..677a395e1c
--- /dev/null
+++ b/uitest/src/test/java/com/vaadin/tests/components/treegrid/TreeGridExpandDataRequestTest.java
@@ -0,0 +1,52 @@
+package com.vaadin.tests.components.treegrid;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vaadin.testbench.elements.TreeGridElement;
+import com.vaadin.tests.tb3.SingleBrowserTest;
+
+public class TreeGridExpandDataRequestTest extends SingleBrowserTest {
+
+    @Override
+    protected Class<?> getUIClass() {
+        return TreeGridBasicFeatures.class;
+    }
+
+    TreeGridElement grid;
+
+    @Before
+    public void before() {
+        openTestURL();
+        grid = $(TreeGridElement.class).first();
+        selectMenuPath("Component", "Features", "Set data provider",
+                "LoggingDataProvider");
+        clearLog();
+    }
+
+    private void clearLog() {
+        selectMenuPath("Settings", "Clear log");
+    }
+
+    @Test
+    public void expand_node0_does_not_request_root_nodes() {
+        grid.expandWithClick(0);
+        Assert.assertFalse("Log should not contain request for root nodes.",
+                logContainsText("Root node request: "));
+    }
+
+    @Test
+    public void expand_node0_after_node1_does_not_request_children_of_node1() {
+        grid.expandWithClick(1);
+        Assert.assertFalse("Log should not contain request for root nodes.",
+                logContainsText("Root node request: "));
+        clearLog();
+        grid.expandWithClick(0);
+        Assert.assertFalse(
+                "Log should not contain request for children of '0 | 1'.",
+                logContainsText("Children request: 0 | 1"));
+        Assert.assertFalse("Log should not contain request for root nodes.",
+                logContainsText("Root node request: "));
+    }
+}