/*
* 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()
{}
}