org.apache.wicket.markup.repeater.data.IDataProvider.java Source code

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Here is the source code for org.apache.wicket.markup.repeater.data.IDataProvider.java

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/*
 * 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.data;

import java.util.Iterator;

import org.apache.wicket.model.IDetachable;
import org.apache.wicket.model.IModel;

/**
 * Interface used to provide data to data views.
 * 
 * Example:
 * 
 * <pre>
 * class UsersProvider implements IDataProvider
 * {
 * 
 *    public Iterator iterator(long first, long count)
 *    {
 *       ((MyApplication)Application.get()).getUserDao().iterator(first, count);
 *    }
 * 
 *    public long size()
 *    {
 *       ((MyApplication)Application.get()).getUserDao().getCount();
 *    }
 * 
 *    public IModel model(Object object)
 *    {
 *       return new DetachableUserModel((User)object);
 *    }
 * }
 * </pre>
 * 
 * You can use the {@link IDetachable#detach()} method for cleaning up your IDataProvider instance.
 * So that you can do one query that returns both the size and the values if your dataset is small
 * enough the be able to do that.
 * 
 * @see IDetachable
 * @see DataViewBase
 * @see DataView
 * @see GridView
 * 
 * @author Igor Vaynberg (ivaynberg)
 * @param <T>
 * 
 */
public interface IDataProvider<T> extends IDetachable {
    /**
     * Gets an iterator for the subset of total data
     * 
     * @param first
     *            first row of data
     * @param count
     *            minimum number of elements to retrieve
     * 
     * @return iterator capable of iterating over {first, first+count} items
     */
    Iterator<? extends T> iterator(long first, long count);

    /**
     * Gets total number of items in the collection represented by the DataProvider
     * 
     * @return total item count
     */
    long size();

    /**
     * Callback used by the consumer of this data provider to wrap objects retrieved from
     * {@link #iterator(long, long)} with a model (usually a detachable one).
     * 
     * @param object
     *            the object that needs to be wrapped
     * 
     * @return the model representation of the object
     */
    IModel<T> model(T object);

    @Override
    default void detach() {
    }
}