/*
* 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.model;
import org.apache.wicket.Component;
/**
* Quick detachable model that is implements the IComponentAssignedModel and the IModel interfaces.
* Its a quick replacement for the current setObject(Component,Object) and getObject(Component)
* methods when the component is needed in a detachable model.
*
* @author jcompagner
*
* @param <T>
* The model object type
*/
public class ComponentDetachableModel<T> implements IComponentAssignedModel<T>
{
private static final long serialVersionUID = 1L;
/**
* Transient flag to prevent multiple detach/attach scenario. We need to maintain this flag as
* we allow 'null' model values.
*/
private transient boolean attached = false;
/**
* This getObject throws an exception.
*
* @see org.apache.wicket.model.IModel#getObject()
*/
@Override
public final T getObject()
{
throw new RuntimeException("get object call not expected on a IComponentAssignedModel");
}
@Override
public final void setObject(T object)
{
throw new RuntimeException("set object call not expected on a IComponentAssignedModel");
}
/**
* Gets whether this model has been attached to the current session.
*
* @return whether this model has been attached to the current session
*/
public final boolean isAttached()
{
return attached;
}
/**
* Set this model in an attached state. Called if the constructor sets the data. (attached)
*/
protected final void setAttached()
{
attached = true;
}
/**
* Attaches to the current request. Implement this method with custom behavior, such as loading
* the model object.
*/
protected void attach()
{
}
/**
* Called when getObject is called in order to retrieve the detachable object. Before this
* method is called, attach() is always called to ensure that the object is attached.
*
* @param component
* The component asking for the object
* @return The object
*/
protected T getObject(Component component)
{
return null;
}
/**
* Called when setObject is called in order to change the detachable object. Before this method
* is called, attach() is always called to ensure that the object is attached.
*
* @param component
* The component asking for replacement of the model object
* @param object
* The new model object
*/
protected void setObject(Component component, T object)
{
}
@Override
public IWrapModel<T> wrapOnAssignment(Component comp)
{
return new WrapModel<T>(comp);
}
private class WrapModel<P> implements IWrapModel<T>
{
private static final long serialVersionUID = 1L;
private final Component component;
/**
* @param comp
*/
public WrapModel(Component comp)
{
component = comp;
}
@Override
public IModel<T> getWrappedModel()
{
return ComponentDetachableModel.this;
}
/**
* Attaches the model.
*/
private void attach()
{
if (!attached)
{
attached = true;
ComponentDetachableModel.this.attach();
}
}
@Override
public T getObject()
{
attach();
return ComponentDetachableModel.this.getObject(component);
}
@Override
public void setObject(T object)
{
attach();
ComponentDetachableModel.this.setObject(component, object);
}
@Override
public void detach()
{
if (attached)
{
attached = false;
ComponentDetachableModel.this.detach();
}
}
}
}