wicket.extensions.markup.html.repeater.data.DataViewBase Maven / Gradle / Ivy

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/*
 * $Id: DataViewBase.java 5044 2006-03-21 00:46:35Z jonathanlocke $ $Revision: 5044 $
 * $Date: 2006-03-21 01:46:35 +0100 (Tue, 21 Mar 2006) $
 * 
 * ==================================================================== 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 wicket.extensions.markup.html.repeater.data;

import java.util.Iterator;

import wicket.extensions.markup.html.repeater.pageable.AbstractPageableView;
import wicket.extensions.markup.html.repeater.refreshing.RefreshingView;
import wicket.markup.html.navigation.paging.IPageable;
import wicket.model.IDetachable;

/**
 * Base class for data views.
 * 
 * Data views aim to make it very simple to populate your repeating view from a
 * database by utilizing {@link IDataProvider} to act as an interface between
 * the database and the dataview.
 * 
 * @see IDataProvider
 * @see DataView
 * @see IPageable
 * @see RefreshingView
 * 
 * @author Igor Vaynberg (ivaynberg)
 * 
 */
public abstract class DataViewBase extends AbstractPageableView
{
	private IDataProvider dataProvider;

	/**
	 * @param id
	 *            component id
	 * @param dataProvider
	 *            data provider
	 */
	public DataViewBase(String id, IDataProvider dataProvider)
	{
		super(id);
		if (dataProvider == null)
		{
			throw new IllegalArgumentException("argument [dataProvider] cannot be null");
		}
		this.dataProvider = dataProvider;
	}

	/**
	 * @return data provider associated with this view
	 */
	protected final IDataProvider internalGetDataProvider()
	{
		return dataProvider;
	}


	protected final Iterator getItemModels(int offset, int count)
	{
		return new ModelIterator(internalGetDataProvider(), offset, count);
	}

	/**
	 * Helper class that converts input from IDataProvider to an iterator over
	 * view items.
	 * 
	 * @author Igor Vaynberg (ivaynberg)
	 * 
	 */
	private static final class ModelIterator implements Iterator
	{
		private Iterator items;
		private IDataProvider dataProvider;
		private int max;
		private int index;

		/**
		 * Constructor
		 * 
		 * @param dataProvider
		 *            data provider
		 * @param offset
		 *            index of first item
		 * @param count
		 *            max number of items to return
		 */
		public ModelIterator(IDataProvider dataProvider, int offset, int count)
		{
			this.items = dataProvider.iterator(offset, count);
			this.dataProvider = dataProvider;
			this.max = count;
		}

		/**
		 * @see java.util.Iterator#remove()
		 */
		public void remove()
		{
			throw new UnsupportedOperationException();
		}

		/**
		 * @see java.util.Iterator#hasNext()
		 */
		public boolean hasNext()
		{
			return items.hasNext() && (index < max);
		}

		/**
		 * @see java.util.Iterator#next()
		 */
		public Object next()
		{
			index++;
			return dataProvider.model(items.next());
		}
	}

	protected final int internalGetItemCount()
	{
		return internalGetDataProvider().size();
	}

	protected void onDetach()
	{
		super.onDetach();
		if (dataProvider instanceof IDetachable)
		{
			((IDetachable)dataProvider).detach();
		}
	}
}