/*
* $Id: LazyValidatorForm.java 471754 2006-11-06 14:55:09Z husted $
*
* 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.struts.validator;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.LazyDynaBean;
import java.util.List;
import java.util.Map;
/**
* <p>Struts <i>Lazy</i> <code>ActionForm</code> which <i>wraps</i> a
* <code>LazyDynaBean</code>.</p>
*
* <p>There isn't really that much to this implementation as most of the
* <i>lazy</i> behaviour is in <code>LazyDynaBean</code> and <i>wrapping</i>
* the <code>LazyDynaBean<code> is handled in the parent
* <code>BeanValidatorForm</code>. The only thing it really does is populate
* <i>indexed</i> properties which are a <code>List<code> type with a
* <code>LazyDynaBean<code> in the <code>get(name, index)</code> method.</p>
*
* <p><i>Lazy</i> DynaBeans provide several types of <i>lazy</i>
* behaviour:</p>
*
* <ul>
*
* <li><b><i>lazy</i> property addition</b> - properties which do not exist
* are automatically added.</li>
*
* <li><b><i>lazy</i> List facilities</b> - automatically <i>grows</i> a
* <code>List</code> or <code>Array</code> to accomodate the index value being
* set.</li>
*
* <li><b><i>lazy</i> List creation</b> - automatic creation of a
* <code>List</code> or <code>Array</code> for <i>indexed</i> properties, if
* it doesn't exist.</li> <li><b><i>lazy</i> Map creation</b> - automatic
* creation of a <code>Map</code> for <i>mapped</i> properties, if it doesn't
* exist.</li>
*
* </ul>
*
* <p>Using this <i>lazy</i> <code>ActionForm</code> means that you don't have
* to define the ActionForm's properties in the <code>struts-config.xml</code>.
* However, a word of warning, everything in the Request gets populated into
* this <code>ActionForm</code> circumventing the normal <i>firewall</i>
* function of Struts forms. Therefore you should only <i>take out</i> of this
* form properties you expect to be there rather than blindly populating all
* the properties into the business tier.</p>
*
* <p>Having said that it is not necessary to pre-define properties in the
* <code>struts-config.xml</code>, it is useful to sometimes do so for
* <i>mapped</i> or <i>indexed</i> properties. For example, if you want to use
* a different <code>Map<code> implementation from the default
* <code>HashMap</code> or an array for indexed properties, rather than the
* default <code>List</code> type:</p>
*
* <pre><code>
* <form-bean name="myForm" type="org.apache.struts.validator.LazyValidatorForm">
* <form-property name="myMap" type="java.util.TreeMap" />
* <form-property name="myBeans" type="org.apache.commons.beanutils.LazyDynaBean[]"
* />
* </form-bean>
* </code></pre>
*
* <p>Another reason for defining <i>indexed</i> properties in the
* <code>struts-config.xml</code> is that if you are validating indexed
* properties using the Validator and none are submitted then the indexed
* property will be <code>null</code> which causes validator to fail.
* Pre-defining them in the <code>struts-config.xml</code> will result in a
* zero-length indexed property (array or List) being instantiated, avoiding
* an issue with validator in that circumstance.</p>
*
* <p>This implementation validates using the ActionForm <i>name</i>. If you
* require a version that validates according to the <i>path</i> then it can
* be easily created in the following manner:</p>
*
* <pre><code>
* public class MyLazyForm extends LazyValidatorForm {
*
* public MyLazyForm () {
* super();
* setPathValidation(true);
* }
*
* }
* </code></pre>
*
* <p>Rather than using this class, another alternative is to either use a
* <code>LazyDynaBean</code> or custom version of <code>LazyDynaBean</code>
* directly. Struts now automatically <i>wraps</i> objects which are not
* <code>ActionForms</code> in a <code>BeanValidatorForm</code>. For
* example:</p>
*
* <pre><code>
* <form-bean name="myForm" type="org.apache.commons.beanutils.LazyDynaBean">
* <form-property name="myBeans" type="org.apache.commons.beanutils.LazyDynaBean[]"
* />
* </form-bean>
* </code></pre>
*
* @version $Rev: 471754 $ $Date: 2005-05-07 12:11:38 -0400 (Sat, 07 May 2005)
* $
* @see <a href="http://jakarta.apache.org/commons/beanutils/apidocs/org/apache/commons/beanutils/package-summary.html#dynamic.lazy">Commons
* BeanUtils JavaDoc</a>
* @since Struts 1.2.6
*/
public class LazyValidatorForm extends BeanValidatorForm {
// ------------------- Constructors ----------------------------------
/**
* Default Constructor which creates a <code>LazyDynaBean</code> to
* <i>back</i> this form.
*/
public LazyValidatorForm() {
super(new LazyDynaBean());
}
/**
*/
public LazyValidatorForm(DynaBean bean) {
super(bean);
}
// ------------------- DynaBean methods ----------------------------------
/**
* <p>Return an indexed property value.</p>
*
* <p>If the "indexed" property is a <code>List</code> type then any
* missing values are populated with a bean (created in the
* <code>newIndexedBean(name)</code> method - in this implementation this
* is a <code>LazyDynaBean</code> type.</p>
*/
public Object get(String name, int index) {
int size = size(name);
// Get the indexed property
Object value = dynaBean.get(name, index);
// Create missing beans for Lists
if (value == null) {
Object indexedValue = dynaBean.get(name);
if (List.class.isAssignableFrom(indexedValue.getClass())) {
for (int i = size; i <= index; i++) {
value = newIndexedBean(name);
set(name, i, value);
}
}
}
return value;
}
// ------------------- Public methods ----------------------------------
/**
* <p>Return the <code>Map</code> containing the property values.</p>
*
* <p>Provided so that properties can be access using JSTL.</p>
*/
public Map getMap() {
return ((LazyDynaBean) dynaBean).getMap();
}
// ------------------- Protected methods ----------------------------------
/**
* <p>Creates new <code>DynaBean</code> instances to populate an 'indexed'
* property of beans - defaults to <code>LazyDynaBean</code> type.</p>
*
* <p>Override this method if you require a different type of
* <code>DynaBean</code>.</p>
*/
protected DynaBean newIndexedBean(String name) {
return new LazyDynaBean();
}
}