feat: grid empty state content

vaadin-grid-flow-parent/vaadin-grid-flow/src/main/java/com/vaadin/flow/component/grid/Grid.java

@@ -64,6 +64,7 @@
 import com.vaadin.flow.component.grid.editor.Editor;
 import com.vaadin.flow.component.grid.editor.EditorImpl;
 import com.vaadin.flow.component.grid.editor.EditorRenderer;
+import com.vaadin.flow.component.html.Span;
 import com.vaadin.flow.component.page.PendingJavaScriptResult;
 import com.vaadin.flow.component.shared.SelectionPreservationHandler;
 import com.vaadin.flow.component.shared.SelectionPreservationMode;
@@ -1457,6 +1458,10 @@ public UpdateQueueData getUpdateQueueData() {
 
     private PendingJavaScriptResult pendingSorterUpdate;
 
+    private static final String EMPTY_STATE_SLOT = "empty-state";
+    private Component emptyStateComponent;
+    private String emptyStateText;
+
     /**
      * Creates a new instance, with page size of 50.
      */
@@ -5056,4 +5061,56 @@ private String getUniqueKey(T item) {
                 .map(provider -> provider.apply(item))
                 .orElse(getDataCommunicator().getKeyMapper().key(item));
     }
+
+    /**
+     * Sets the component to be displayed when the grid is empty.
+     *
+     * @param emptyStateComponent
+     *            the component to be displayed when the grid is empty
+     */
+    public void setEmptyStateComponent(Component emptyStateComponent) {
+        this.emptyStateText = null;
+        this.emptyStateComponent = emptyStateComponent;
+        updateEmptyStateContent();
+    }
+
+    /**
+     * Sets the text to be displayed when the grid is empty.
+     *
+     * @param emptyStateText
+     *            the text to be displayed when the grid is empty
+     */
+    public void setEmptyStateText(String emptyStateText) {
+        this.emptyStateComponent = null;
+        this.emptyStateText = emptyStateText;
+        updateEmptyStateContent();
+    }
+
+    /**
+     * Returns the component that is displayed when the grid is empty.
+     *
+     * @return the component that is displayed when the grid is empty
+     */
+    public Component getEmptyStateComponent() {
+        return emptyStateComponent;
+    }
+
+    /**
+     * Returns the text that is displayed when the grid is empty.
+     *
+     * @return the text that is displayed when the grid is empty
+     */
+    public String getEmptyStateText() {
+        return emptyStateText;
+    }
+
+    private void updateEmptyStateContent() {
+        if (emptyStateComponent != null) {
+            SlotUtils.setSlot(this, EMPTY_STATE_SLOT, emptyStateComponent);
+        } else if (emptyStateText != null) {
+            SlotUtils.setSlot(this, EMPTY_STATE_SLOT, new Span(emptyStateText));
+        } else {
+            SlotUtils.clearSlot(this, EMPTY_STATE_SLOT);
+        }
+    }
 }

vaadin-grid-flow-parent/vaadin-grid-flow/src/test/java/com/vaadin/flow/component/grid/GridEmptyStateTest.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2000-2024 Vaadin Ltd.
+ *
+ * Licensed 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 com.vaadin.flow.component.grid;
+
+import java.util.Optional;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.dom.Element;
+
+public class GridEmptyStateTest {
+
+    private Grid<String> grid;
+
+    @Before
+    public void setup() {
+        grid = new Grid<>();
+    }
+
+    @Test
+    public void setEmptyStateComponent_hasEmptyStateComponent() {
+        var content = new Div();
+        grid.setEmptyStateComponent(content);
+        Assert.assertEquals(content.getElement(), getEmptyStateElement());
+    }
+
+    @Test
+    public void setEmptyStateText_hasEmptyStateText() {
+        var content = "empty";
+        grid.setEmptyStateText(content);
+        var emptyStateElement = getEmptyStateElement();
+        Assert.assertEquals(content, emptyStateElement.getText());
+        Assert.assertEquals("span", emptyStateElement.getTag());
+    }
+
+    @Test
+    public void setEmptyStateComponent_overridesEmptyStateText() {
+        grid.setEmptyStateText("empty");
+        var content = new Div();
+        grid.setEmptyStateComponent(content);
+        Assert.assertEquals(content.getElement(), getEmptyStateElement());
+    }
+
+    @Test
+    public void setEmptyStateText_overridesEmptyStateComponent() {
+        var content = "empty";
+        grid.setEmptyStateComponent(new Div());
+        grid.setEmptyStateText(content);
+        var emptyStateElement = getEmptyStateElement();
+        Assert.assertEquals(content, emptyStateElement.getText());
+        Assert.assertEquals("span", emptyStateElement.getTag());
+    }
+
+    @Test
+    public void setEmptyStateComponentNull_noEmptyStateComponent() {
+        grid.setEmptyStateText("empty");
+        grid.setEmptyStateComponent(null);
+        Assert.assertTrue(getEmptyStateElementOptional().isEmpty());
+    }
+
+    @Test
+    public void setEmptyStateTextNull_noEmptyStateComponent() {
+        grid.setEmptyStateText("empty");
+        grid.setEmptyStateText(null);
+        Assert.assertTrue(getEmptyStateElementOptional().isEmpty());
+    }
+
+    @Test
+    public void setEmptyStateComponent_getEmptyStateComponent() {
+        var content = new Div();
+        grid.setEmptyStateComponent(content);
+        Assert.assertEquals(content, grid.getEmptyStateComponent());
+    }
+
+    @Test
+    public void setEmptyStateText_getEmptyStateText() {
+        var content = "empty";
+        grid.setEmptyStateText(content);
+        Assert.assertEquals(content, grid.getEmptyStateText());
+    }
+
+    @Test
+    public void setEmptyStateComponent_setEmptyStateText_getEmptyStateComponent() {
+        grid.setEmptyStateComponent(new Div());
+        grid.setEmptyStateText("empty");
+        Assert.assertNull(grid.getEmptyStateComponent());
+    }
+
+    @Test
+    public void setEmptyStateText_setEmptyStateComponent_getEmptyStateText() {
+        grid.setEmptyStateText("empty");
+        grid.setEmptyStateComponent(new Div());
+        Assert.assertNull(grid.getEmptyStateText());
+    }
+
+    @Test
+    public void setEmptyStateComponent_setEmptyStateTextNull_getEmptyStateComponent() {
+        grid.setEmptyStateComponent(new Div());
+        grid.setEmptyStateText(null);
+        Assert.assertNull(grid.getEmptyStateComponent());
+        Assert.assertNull(grid.getEmptyStateText());
+    }
+
+    @Test
+    public void setEmptyStateText_setEmptyStateComponentNull_getEmptyStateText() {
+        grid.setEmptyStateText("empty");
+        grid.setEmptyStateComponent(null);
+        Assert.assertNull(grid.getEmptyStateComponent());
+        Assert.assertNull(grid.getEmptyStateText());
+    }
+
+    private Element getEmptyStateElement() {
+        return getEmptyStateElementOptional().orElse(null);
+    }
+
+    private Optional<Element> getEmptyStateElementOptional() {
+        return grid.getElement().getChildren().filter(
+                child -> child.getAttribute("slot").equals("empty-state"))
+                .findFirst();
+    }
+}