Add listing extension to allow access to data communicator

Change-Id: I4eca9884cf0195bab68d282bf1a6fd8c8b48a0fb

2 files changed, 110 insertions, 17 deletions

diff --git a/server/src/main/java/com/vaadin/ui/AbstractListing.java b/server/src/main/java/com/vaadin/ui/AbstractListing.java
index 05f31d7b81..b5780f57e9 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractListing.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractListing.java
@@ -15,7 +15,10 @@
  */
 package com.vaadin.ui;
 
+import java.util.Objects;
+
 import com.vaadin.data.Listing;
+import com.vaadin.server.AbstractExtension;
 import com.vaadin.server.data.DataCommunicator;
 import com.vaadin.server.data.DataSource;
 import com.vaadin.server.data.TypedDataGenerator;
@@ -30,6 +33,72 @@ import com.vaadin.server.data.TypedDataGenerator;
 public abstract class AbstractListing<T> extends AbstractComponent
         implements Listing<T> {
 
+    /**
+     * Helper base class for creating extensions for Listing components. This
+     * class provides helpers for accessing the underlying parts of the
+     * component and its communicational mechanism.
+     *
+     * @param <T>
+     *            listing data type
+     */
+    public abstract static class AbstractListingExtension<T>
+            extends AbstractExtension implements TypedDataGenerator<T> {
+
+        /**
+         * {@inheritDoc}
+         * <p>
+         * Note: AbstractListingExtensions need parent to be of type
+         * AbstractListing.
+         *
+         * @throws IllegalArgument
+         *             if parent is not an AbstractListing
+         */
+        public void extend(Listing<T> listing) {
+            if (listing instanceof AbstractListing) {
+                AbstractListing<T> parent = (AbstractListing<T>) listing;
+                super.extend(parent);
+                parent.addDataGenerator(this);
+            } else {
+                throw new IllegalArgumentException(
+                        "Parent needs to extend AbstractListing");
+            }
+        }
+
+        @Override
+        public void remove() {
+            getParent().removeDataGenerator(this);
+
+            super.remove();
+        }
+
+        /**
+         * Gets a data object based on its client-side identifier key.
+         *
+         * @param key
+         *            key for data object
+         * @return the data object
+         */
+        protected T getData(String key) {
+            return getParent().getDataCommunicator().getKeyMapper().get(key);
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public AbstractListing<T> getParent() {
+            return (AbstractListing<T>) super.getParent();
+        }
+
+        /**
+         * Helper method for refreshing a single data object.
+         *
+         * @param data
+         *            data object to refresh
+         */
+        protected void refresh(T data) {
+            getParent().getDataCommunicator().refresh(data);
+        }
+    }
+
     /* DataCommunicator for this Listing component */
     private final DataCommunicator<T> dataCommunicator;
 
@@ -53,6 +122,8 @@ public abstract class AbstractListing<T> extends AbstractComponent
      *            a customized data communicator instance
      */
     protected AbstractListing(DataCommunicator<T> dataCommunicator) {
+        Objects.requireNonNull(dataCommunicator,
+                "The data communicator can't be null");
         this.dataCommunicator = dataCommunicator;
         addExtension(dataCommunicator);
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingTest.java
index b3d606cc30..2bc13dc4f3 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingTest.java
@@ -13,25 +13,14 @@ import com.vaadin.server.data.BackEndDataSource;
 import com.vaadin.server.data.DataSource;
 import com.vaadin.server.data.ListDataSource;
 import com.vaadin.server.data.Query;
-import com.vaadin.server.data.TypedDataGenerator;
 import com.vaadin.ui.AbstractListing;
+import com.vaadin.ui.AbstractListing.AbstractListingExtension;
 
 import elemental.json.JsonObject;
 
 public class AbstractListingTest {
 
     private final class TestListing extends AbstractListing<String> {
-
-        @Override
-        public void addDataGenerator(TypedDataGenerator<String> generator) {
-            super.addDataGenerator(generator);
-        }
-
-        @Override
-        public void removeDataGenerator(TypedDataGenerator<String> generator) {
-            super.removeDataGenerator(generator);
-        }
-
         /**
          * Used to execute data generation
          */
@@ -40,7 +29,8 @@ public class AbstractListingTest {
         }
     }
 
-    private final class CountGenerator implements TypedDataGenerator<String> {
+    private final class CountGenerator
+            extends AbstractListingExtension<String> {
 
         int callCount = 0;
 
@@ -52,6 +42,11 @@ public class AbstractListingTest {
         @Override
         public void destroyData(String data) {
         }
+
+        @Override
+        public void refresh(String data) {
+            super.refresh(data);
+        }
     }
 
     private static final String[] ITEM_ARRAY = new String[] { "Foo", "Bar",
@@ -102,7 +97,7 @@ public class AbstractListingTest {
     @Test
     public void testAddDataGeneartorBeforeDataSource() {
         CountGenerator generator = new CountGenerator();
-        listing.addDataGenerator(generator);
+        generator.extend(listing);
         listing.setItems("Foo");
         listing.runDataGeneration();
         Assert.assertEquals("Generator should have been called once", 1,
@@ -113,20 +108,47 @@ public class AbstractListingTest {
     public void testAddDataGeneartorAfterDataSource() {
         CountGenerator generator = new CountGenerator();
         listing.setItems("Foo");
-        listing.addDataGenerator(generator);
+        generator.extend(listing);
+        listing.runDataGeneration();
+        Assert.assertEquals("Generator should have been called once", 1,
+                generator.callCount);
+    }
+
+    @Test
+    public void testDataNotGeneratedTwice() {
+        listing.setItems("Foo");
+        CountGenerator generator = new CountGenerator();
+        generator.extend(listing);
         listing.runDataGeneration();
         Assert.assertEquals("Generator should have been called once", 1,
                 generator.callCount);
+        listing.runDataGeneration();
+        Assert.assertEquals("Generator should not have been called again", 1,
+                generator.callCount);
     }
 
     @Test
     public void testRemoveDataGeneartor() {
         listing.setItems("Foo");
         CountGenerator generator = new CountGenerator();
-        listing.addDataGenerator(generator);
-        listing.removeDataGenerator(generator);
+        generator.extend(listing);
+        generator.remove();
         listing.runDataGeneration();
         Assert.assertEquals("Generator should not have been called", 0,
                 generator.callCount);
     }
+
+    @Test
+    public void testDataRefresh() {
+        listing.setItems("Foo");
+        CountGenerator generator = new CountGenerator();
+        generator.extend(listing);
+        listing.runDataGeneration();
+        Assert.assertEquals("Generator should have been called once", 1,
+                generator.callCount);
+        generator.refresh("Foo");
+        listing.runDataGeneration();
+        Assert.assertEquals("Generator should have been called again", 2,
+                generator.callCount);
+    }
 }