/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.wicket.markup.repeater;
import java.util.Iterator;
import org.apache.wicket.markup.repeater.util.ModelIteratorAdapter;
import org.apache.wicket.model.IModel;
import org.apache.wicket.version.undo.Change;
/**
* An abstract repeater view that provides refreshing functionality to its
* subclasses. The view is refreshed every request, making it well suited for
* displaying dynamic data.
* <p>
* The view is populated by implementing {@link RefreshingView#getItemModels() }
* and {@link RefreshingView#populateItem(Item) } methods. RefreshingView builds
* the items that will be rendered by looping over the models retrieved from
* {@link RefreshingView#getItemModels() } and calling the
* {@link RefreshingView#newItem(String, int, IModel) } to generate the child
* item container followed by a call to
* {@link RefreshingView#populateItem(Item) } to let the user populate the newly
* created item container with custom components.
* </p>
* <p>
* The provided {@link ModelIteratorAdapter} can make implementing
* {@link RefreshingView#getItemModels() } easier if you have an iterator over
* item objects.
* </p>
*
* @see RepeatingView
* @see ModelIteratorAdapter
*
* @author Igor Vaynberg (ivaynberg)
*
*/
public abstract class RefreshingView extends RepeatingView
{
private static final long serialVersionUID = 1L;
/**
* The item reuse strategy that will be used to recycle items when the page
* is changed or the view is redrawn.
*
* @see IItemReuseStrategy
*/
private IItemReuseStrategy itemReuseStrategy;
/**
* Constructor
*
* @param id
* component id
*/
public RefreshingView(String id)
{
super(id);
}
/**
* Constructor
*
* @param id
* component id
* @param model
* model
*/
public RefreshingView(String id, IModel model)
{
super(id, model);
}
/**
* Refresh the items in the view. Delegates the creation of items to the
* selected item reuse strategy
*/
protected void onBeforeRender()
{
super.onBeforeRender();
if (isVisibleInHierarchy())
{
IItemFactory itemFactory = new IItemFactory()
{
public Item newItem(int index, IModel model)
{
String id = RefreshingView.this.newChildId();
Item item = RefreshingView.this.newItem(id, index, model);
RefreshingView.this.populateItem(item);
return item;
}
};
Iterator models = getItemModels();
Iterator items = getItemReuseStrategy().getItems(itemFactory, models, getItems());
removeAll();
addItems(items);
}
}
/**
* Returns an iterator over models for items that will be added to this view
*
* @return an iterator over models for items that will be added to this view
*/
protected abstract Iterator getItemModels();
/**
* Populate the given Item container.
* <p>
* <b>be carefull</b> to add any components to the item and not the view
* itself. So, don't do:
*
* <pre>
* add(new Label("foo", "bar"));
* </pre>
*
* but:
*
* <pre>
* item.add(new Label("foo", "bar"));
* </pre>
*
* </p>
*
* @param item
* The item to populate
*/
protected abstract void populateItem(final Item item);
/**
* Factory method for Item container. Item containers are simple
* MarkupContainer used to aggregate the user added components for a row
* inside the view.
*
* @see Item
* @param id
* component id for the new data item
* @param index
* the index of the new data item
* @param model
* the model for the new data item
*
* @return DataItem created DataItem
*/
protected Item newItem(final String id, int index, final IModel model)
{
return new Item(id, index, model);
}
/**
* @return iterator over item instances that exist as children of this view
*/
public Iterator getItems()
{
return iterator();
}
/**
* Add items to the view. Prior to this all items were removed so every
* request this function starts from a clean slate.
*
* @param items
* item instances to be added to this view
*/
protected void addItems(Iterator items)
{
while (items.hasNext())
{
add((Item)items.next());
}
}
// /////////////////////////////////////////////////////////////////////////
// ITEM GENERATION
// /////////////////////////////////////////////////////////////////////////
/**
* @return currently set item reuse strategy. Defaults to
* <code>DefaultItemReuseStrategy</code> if none was set.
*
* @see DefaultItemReuseStrategy
*/
public IItemReuseStrategy getItemReuseStrategy()
{
if (itemReuseStrategy == null)
{
return DefaultItemReuseStrategy.getInstance();
}
return itemReuseStrategy;
}
/**
* Sets the item reuse strategy. This strategy controls the creation of
* {@link Item}s.
*
* @see IItemReuseStrategy
*
* @param strategy
* item reuse strategy
* @return this for chaining
*/
public RefreshingView setItemReuseStrategy(IItemReuseStrategy strategy)
{
if (strategy == null)
{
throw new IllegalArgumentException();
}
if (!strategy.equals(itemReuseStrategy))
{
if (isVersioned())
{
addStateChange(new Change()
{
private static final long serialVersionUID = 1L;
private final IItemReuseStrategy old = itemReuseStrategy;
public void undo()
{
itemReuseStrategy = old;
}
public String toString()
{
return "ItemsReuseStrategyChange[component: " + getPath() + ", reuse: "
+ old + "]";
}
});
}
itemReuseStrategy = strategy;
}
return this;
}
}