001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.model;
018
019import org.apache.wicket.Component;
020
021/**
022 * Models that wish to substitute themselves with a wrapper when they are bound to a component
023 * (either through IModel parameter in a constructor or via a call to
024 * {@link Component#setDefaultModel(IModel)}) should implement this interface. One reason for a
025 * model to want to do this is if it needs to be aware of the component it is bound to.
026 * 
027 * The algorithm wicket employs is similar to this:
028 * 
029 * <pre>
030 * void Component.setModel(IModel model) 
031 * {
032 *     if (model instanceof IComponentAssignedModel) 
033 *     {
034 *        this.model = ((IComponentAssignedModel)model).wrapOnAssignment(this);
035 *     } 
036 *     else 
037 *     {
038 *        this.model = model;
039 *     }
040 * }
041 * </pre>
042 * 
043 * For an example see {@link ResourceModel}
044 * 
045 * @author jcompagner
046 * @author Igor Vaynberg (ivaynberg)
047 * @param <T>
048 *            The model data type
049 */
050public interface IComponentAssignedModel<T> extends IModel<T>
051{
052        /**
053         * This method is called when the component gets its model assigned.
054         * 
055         * WARNING: Because the model can be assigned in the constructor of component this method can
056         * also be called with a 'this' of a component that is not fully constructed yet.
057         * 
058         * @param component
059         * @return The WrapModel that wraps this model
060         */
061        IWrapModel<T> wrapOnAssignment(Component component);
062}