001 // Copyright 2004, 2005 The Apache Software Foundation
002 //
003 // Licensed under the Apache License, Version 2.0 (the "License");
004 // you may not use this file except in compliance with the License.
005 // You may obtain a copy of the License at
006 //
007 // http://www.apache.org/licenses/LICENSE-2.0
008 //
009 // Unless required by applicable law or agreed to in writing, software
010 // distributed under the License is distributed on an "AS IS" BASIS,
011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012 // See the License for the specific language governing permissions and
013 // limitations under the License.
014
015 package org.apache.tapestry.form;
016
017 import org.apache.tapestry.IMarkupWriter;
018 import org.apache.tapestry.IRequestCycle;
019 import org.apache.tapestry.valid.ValidatorException;
020
021 /**
022 * Implements a component that manages an HTML <input type=checkbox> form element. [ <a
023 * href="../../../../../ComponentReference/Checkbox.html">Component Reference </a>]
024 * <p>
025 * As of 4.0, this component can be validated.
026 *
027 * @author Howard Lewis Ship
028 * @author Paul Ferraro
029 */
030 public abstract class Checkbox extends AbstractFormComponent implements ValidatableField
031 {
032 /**
033 * @see org.apache.tapestry.form.validator.AbstractRequirableField#renderRequirableFormComponent(org.apache.tapestry.IMarkupWriter,
034 * org.apache.tapestry.IRequestCycle)
035 */
036 protected void renderFormComponent(IMarkupWriter writer, IRequestCycle cycle)
037 {
038 renderDelegatePrefix(writer, cycle);
039
040 writer.beginEmpty("input");
041 writer.attribute("type", "checkbox");
042
043 writer.attribute("name", getName());
044
045 if (isDisabled())
046 writer.attribute("disabled", "disabled");
047
048 if (getValue())
049 writer.attribute("checked", "checked");
050
051 renderIdAttribute(writer, cycle);
052
053 getValidatableFieldSupport().renderContributions(this, writer, cycle);
054
055 renderInformalParameters(writer, cycle);
056
057 writer.closeTag();
058
059 renderDelegateSuffix(writer, cycle);
060 }
061
062 /**
063 * In traditional HTML, many checkboxes would have the same name but different values. Under
064 * Tapestry, it makes more sense to have different names and a fixed value. For a checkbox, we
065 * only care about whether the name appears as a request parameter.
066 */
067 protected void rewindFormComponent(IMarkupWriter writer, IRequestCycle cycle)
068 {
069 String value = cycle.getParameter(getName());
070
071 try
072 {
073 // This is atypical validation - since this component does not explicitly bind to an object
074 getValidatableFieldSupport().validate(this, writer, cycle, value);
075
076 setValue(value != null);
077 }
078 catch (ValidatorException e)
079 {
080 getForm().getDelegate().record(e);
081 }
082 }
083
084 public abstract boolean getValue();
085
086 public abstract void setValue(boolean selected);
087
088 /**
089 * Injected.
090 */
091 public abstract ValidatableFieldSupport getValidatableFieldSupport();
092
093 /**
094 * @see org.apache.tapestry.form.AbstractFormComponent#isRequired()
095 */
096 public boolean isRequired()
097 {
098 return getValidatableFieldSupport().isRequired(this);
099 }
100 }