feat(demo): add demo for empty grid label

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/EmptyGridLabelDemo.java

@@ -0,0 +1,100 @@
+/*-
+ * #%L
+ * Grid Helpers Add-on
+ * %%
+ * Copyright (C) 2022 Flowing Code
+ * %%
+ * 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.
+ * #L%
+ */
+
+package com.flowingcode.vaadin.addons.gridhelpers;
+
+import com.flowingcode.vaadin.addons.demo.DemoSource;
+import com.flowingcode.vaadin.addons.gridhelpers.LazyTestData.PersonFilter;
+import com.vaadin.flow.component.Key;
+import com.vaadin.flow.component.Text;
+import com.vaadin.flow.component.button.Button;
+import com.vaadin.flow.component.formlayout.FormLayout;
+import com.vaadin.flow.component.formlayout.FormLayout.ResponsiveStep;
+import com.vaadin.flow.component.grid.Grid;
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.component.html.H3;
+import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
+import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.vaadin.flow.component.textfield.TextField;
+import com.vaadin.flow.data.provider.DataProvider;
+import com.vaadin.flow.data.provider.Query;
+import com.vaadin.flow.router.PageTitle;
+import com.vaadin.flow.router.Route;
+import java.util.function.Function;
+
+@PageTitle("Empty Grid Label")
+@DemoSource
+@Route(value = "grid-helpers/empty-grid-label", layout = GridHelpersDemoView.class)
+public class EmptyGridLabelDemo extends VerticalLayout {
+
+  public EmptyGridLabelDemo() {
+    LazyTestData data = new LazyTestData();
+
+    setSpacing(false);
+    setPadding(false);
+    setSizeFull();
+
+    TextField firstName = new TextField("Firstname");
+    TextField lastName = new TextField("Lastname");
+
+    Function<Query<Person, PersonFilter>, PersonFilter> filterBuilder = query -> {
+      PersonFilter filter = query.getFilter().orElse(new PersonFilter());
+      filter.setFirstName(firstName.getValue());
+      filter.setLastName(lastName.getValue());
+      return filter;
+    };
+
+    DataProvider<Person, PersonFilter> dataProvider = DataProvider.fromFilteringCallbacks(
+        query -> data.filter(query.getOffset(), query.getPageSize(), filterBuilder.apply(query)),
+        query -> data.count(filterBuilder.apply(query)));
+
+    Grid<Person> grid = new Grid<>();
+    grid.setDataProvider(dataProvider);
+    grid.addColumn(Person::getFirstName).setHeader("First name");
+    grid.addColumn(Person::getLastName).setHeader("Last name");
+    grid.addColumn(Person::getCountry).setHeader("Country");
+    grid.setSizeFull();
+
+    Div emptyGridLabel = new Div(new Text("No records found"));
+    emptyGridLabel.setSizeFull();
+    emptyGridLabel.addClassName("empty-grid-label");
+    emptyGridLabel.setVisible(false);
+    GridHelper.setEmptyGridLabel(grid, emptyGridLabel);
+
+    Button filterButton = new Button("Filter");
+    filterButton.addClickShortcut(Key.ENTER);
+    filterButton.addClickListener(e -> dataProvider.refreshAll());
+
+    Div gridContainer = new Div(grid, emptyGridLabel);
+    gridContainer.getStyle().set("position", "relative");
+    gridContainer.setSizeFull();
+
+    FormLayout filtersForm = new FormLayout(firstName, lastName);
+    filtersForm.setResponsiveSteps(new ResponsiveStep("0", 2));
+    filtersForm.setWidthFull();
+
+    HorizontalLayout filters = new HorizontalLayout(filtersForm, filterButton);
+    filters.setAlignItems(Alignment.END);
+    filters.setWidthFull();
+    filters.getStyle().set("padding-right", "4px");
+
+    add(filters, gridContainer);
+  }
+}

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/GridHelpersDemoView.java

@@ -50,5 +50,6 @@ public GridHelpersDemoView() {
     addDemo(GetHeaderFooterDemo.class);
     addDemo(LazyMultiSelectionDemo.class);
     addDemo(CheckboxColumnDemo.class);
+    addDemo(EmptyGridLabelDemo.class);
   }
 }

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/LazyTestData.java

@@ -24,6 +24,9 @@
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import lombok.Getter;
+import lombok.Setter;
+import org.apache.commons.lang3.StringUtils;
 
 class LazyTestData {
 
@@ -52,15 +55,33 @@ public LazyTestData() {
   }
 
   public Stream<Person> filter(int offset, int pageSize) {
+    return filter(offset, pageSize, null);
+  }
+
+  public Stream<Person> filter(int offset, int pageSize, PersonFilter filter) {
     int from = Math.max(0, offset);
-    int to = Math.min(data.size(), pageSize + offset);
-    return data.subList(from, to).stream();
+    if (filter != null) {
+      return data.stream()
+          .filter(
+              item -> StringUtils.containsIgnoreCase(item.getFirstName(), filter.getFirstName()))
+          .filter(item -> StringUtils.containsIgnoreCase(item.getLastName(), filter.getLastName()))
+          .skip(from)
+          .limit(pageSize);
+    }
+    return data.stream().skip(from).limit(pageSize);
   }
 
   public int count() {
     return data.size();
   }
 
+  public int count(PersonFilter filter) {
+    return (int) data.stream()
+        .filter(item -> StringUtils.containsIgnoreCase(item.getFirstName(), filter.getFirstName()))
+        .filter(item -> StringUtils.containsIgnoreCase(item.getLastName(), filter.getLastName()))
+        .count();
+  }
+
   private static String generateCountry() {
     String country = faker.address().country();
     if (country.contains("South Georgia") || country.contains("Falkland")) {
@@ -69,4 +90,12 @@ private static String generateCountry() {
       return country;
     }
   }
+
+  @Getter
+  @Setter
+  public static class PersonFilter {
+    private String firstName;
+    private String lastName;
+  }
+
 }

src/test/resources/META-INF/resources/gridhelpers/styles.css

@@ -24,3 +24,13 @@ label.label {
 	font-weight: 500;
 	line-height: 1;
 }
+
+.empty-grid-label {
+  position: absolute;
+  top: 0px;
+  left: 0px;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  font-size: 32px;
+}