Author: niallp Date: Wed Nov 3 14:34:19 2004 New Revision: 56532 Added: struts/trunk/src/share/org/apache/struts/validator/LazyValidatorForm.java Log: add LazyValidatorForm
Added: struts/trunk/src/share/org/apache/struts/validator/LazyValidatorForm.java ============================================================================== --- (empty file) +++ struts/trunk/src/share/org/apache/struts/validator/LazyValidatorForm.java Wed Nov 3 14:34:19 2004 @@ -0,0 +1,173 @@ +/* + * Copyright 2004 The Apache Software Foundation. + * + * Licensed 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 java.util.Map; +import java.util.List; +import org.apache.commons.beanutils.DynaBean; +import org.apache.commons.beanutils.LazyDynaBean; +import org.apache.commons.beanutils.LazyDynaMap; + +/** + * <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> + * + * @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(); + } + +} \ No newline at end of file --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
