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
015package org.apache.tapestry.contrib.form;
016
017import org.apache.hivemind.ApplicationRuntimeException;
018import org.apache.hivemind.HiveMind;
019import org.apache.tapestry.AbstractComponent;
020import org.apache.tapestry.IActionListener;
021import org.apache.tapestry.IForm;
022import org.apache.tapestry.IMarkupWriter;
023import org.apache.tapestry.IRequestCycle;
024import org.apache.tapestry.Tapestry;
025import org.apache.tapestry.TapestryUtils;
026import org.apache.tapestry.form.IFormComponent;
027import org.apache.tapestry.listener.ListenerInvoker;
028import org.apache.tapestry.services.DataSqueezer;
029
030/**
031 * A conditional element on a page which will render its wrapped elements zero or one times. This
032 * component is a variant of {@link org.apache.tapestry.components.Conditional}, but is designed
033 * for operation in a form. The component parameters are stored in hidden fields during rendering
034 * and are taken from those fields during the rewind, thus no StaleLink exceptions occur. [ <a
035 * href="../../../../../ComponentReference/contrib.FormConditional.html">Component Reference </a>]
036 * 
037 * @author Mindbridge
038 * @since 3.0
039 */
040
041public abstract class FormConditional extends AbstractComponent implements IFormComponent
042{
043    protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
044    {
045        IForm form = TapestryUtils.getForm(cycle, this);
046
047        boolean cycleRewinding = cycle.isRewinding();
048
049        // If the cycle is rewinding, but not this particular form,
050        // then do nothing (don't even render the body).
051
052        if (cycleRewinding && !form.isRewinding())
053            return;
054
055        String name = form.getElementId(this);
056
057        boolean condition = getCondition(cycle, form, name);
058
059        getListenerInvoker().invokeListener(getListener(), this, cycle);
060
061        // render the component body only if the condition is true
062        if (condition)
063        {
064            String element = getElement();
065
066            boolean render = !cycleRewinding && HiveMind.isNonBlank(element);
067
068            if (render)
069            {
070                writer.begin(element);
071                renderInformalParameters(writer, cycle);
072            }
073
074            renderBody(writer, cycle);
075
076            if (render)
077                writer.end(element);
078        }
079    }
080
081    private boolean getCondition(IRequestCycle cycle, IForm form, String name)
082    {
083        boolean condition;
084
085        if (!cycle.isRewinding())
086        {
087            condition = getCondition();
088            writeValue(form, name, condition);
089        }
090        else
091        {
092            String submittedCondition = cycle.getParameter(name);
093            condition = convertValue(submittedCondition);
094        }
095
096        if (isParameterBound("conditionValue"))
097            setConditionValue(condition);
098
099        return condition;
100    }
101
102    private void writeValue(IForm form, String name, boolean value)
103    {
104        String externalValue;
105
106        try
107        {
108            externalValue = getDataSqueezer().squeeze(value ? Boolean.TRUE : Boolean.FALSE);
109        }
110        catch (Exception ex)
111        {
112            throw new ApplicationRuntimeException(Tapestry.format(
113                    "FormConditional.unable-to-convert-value",
114                    Boolean.toString(value)), this, null, ex);
115        }
116
117        form.addHiddenValue(name, externalValue);
118    }
119
120    private boolean convertValue(String value)
121    {
122        try
123        {
124            Boolean b = (Boolean) getDataSqueezer().unsqueeze(value);
125            return b.booleanValue();
126        }
127        catch (Exception ex)
128        {
129            throw new ApplicationRuntimeException(Tapestry.format(
130                    "FormConditional.unable-to-convert-string",
131                    value), this, null, ex);
132        }
133    }
134
135    public abstract DataSqueezer getDataSqueezer();
136
137    // Part of the FormElement interface.
138
139    public boolean isDisabled()
140    {
141        return false;
142    }
143
144    public abstract boolean getCondition();
145
146    public abstract void setConditionValue(boolean value);
147
148    public abstract String getElement();
149
150    public abstract IActionListener getListener();
151
152    /**
153     * Injected.
154     * 
155     * @since 4.0
156     */
157
158    public abstract ListenerInvoker getListenerInvoker();
159
160}