001// Copyright 2009, 2010, 2011 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.tapestry5.corelib.components;
016
017import org.apache.tapestry5.*;
018import org.apache.tapestry5.annotations.Environmental;
019import org.apache.tapestry5.annotations.Parameter;
020import org.apache.tapestry5.annotations.SupportsInformalParameters;
021import org.apache.tapestry5.dom.Element;
022import org.apache.tapestry5.ioc.annotations.Inject;
023import org.apache.tapestry5.ioc.internal.util.InternalUtils;
024import org.apache.tapestry5.services.ComponentDefaultProvider;
025import org.apache.tapestry5.services.FormSupport;
026import org.apache.tapestry5.services.Request;
027import org.apache.tapestry5.services.javascript.JavaScriptSupport;
028
029/**
030 * Used to record a page property as a value into the form. The value is encoded
031 * when the form is rendered, then decoded after the form is submitted back to
032 * the server, and the "value" parameter updated.
033 * <p/>
034 * The encoding and decoding is done via a {@link org.apache.tapestry5.ValueEncoder},
035 * therefore you must either bind the "encoder" parameter to a ValueEncoder or
036 * use an entity type for the "value" parameter for which Tapestry can provide a
037 * ValueEncoder automatically.
038 * 
039 * @tapestrydoc
040 * @since 5.1.0.2
041 */
042@SupportsInformalParameters
043public class Hidden implements ClientElement
044{
045    /**
046     * The value to read (when rendering) or update (when the form is submitted).
047     */
048    @Parameter(required = true, autoconnect = true, principal = true)
049    private Object value;
050
051    /**
052     * Defines how nulls on the server side, or sent from the client side, are treated. The selected strategy may
053     * replace the nulls with some other value. The default strategy leaves nulls alone.  Another built-in strategy,
054     * zero, replaces nulls with the value 0.
055     */
056    @Parameter(defaultPrefix = BindingConstants.NULLFIELDSTRATEGY, value = "default")
057    private NullFieldStrategy nulls;
058
059    /**
060     * A ValueEncoder used to convert the server-side object provided by the
061     * "value" parameter into a unique client-side string (typically an ID) and
062     * back. Note: this parameter may be OMITTED if Tapestry is configured to
063     * provide a ValueEncoder automatically for the type of property bound to
064     * the "value" parameter. 
065     */
066    @Parameter(required = true)
067    private ValueEncoder encoder;
068
069    private String clientId;
070
071    private String controlName;
072
073    private Element hiddenInputElement;
074
075    @Environmental(false)
076    private FormSupport formSupport;
077
078    @Environmental
079    private JavaScriptSupport jsSupport;
080
081    @Inject
082    private ComponentResources resources;
083
084    @Inject
085    private ComponentDefaultProvider defaultProvider;
086
087    @Inject
088    private Request request;
089
090    ValueEncoder defaultEncoder()
091    {
092        return defaultProvider.defaultValueEncoder("value", resources);
093    }
094
095    static class ProcessSubmission implements ComponentAction<Hidden>
096    {
097        private final String controlName;
098
099        public ProcessSubmission(String controlName)
100        {
101            this.controlName = controlName;
102        }
103
104        public void execute(Hidden component)
105        {
106            component.processSubmission(controlName);
107        }
108    }
109
110    boolean beginRender(MarkupWriter writer)
111    {
112        if (formSupport == null)
113        {
114            throw new RuntimeException("The Hidden component must be enclosed by a Form component.");
115        }
116
117        controlName = formSupport.allocateControlName(resources.getId());
118
119        clientId = null;
120
121        formSupport.store(this, new ProcessSubmission(controlName));
122
123        Object toEncode = value == null ? nulls.replaceToClient() : value;
124
125        String encoded = toEncode == null ? "" : encoder.toClient(toEncode);
126
127        hiddenInputElement = writer.element("input", "type", "hidden", "name", controlName, "value", encoded);
128
129        resources.renderInformalParameters(writer);
130
131        writer.end();
132
133        return false;
134    }
135
136    private void processSubmission(String controlName)
137    {
138        String encoded = request.getParameter(controlName);
139
140        String toDecode = InternalUtils.isBlank(encoded) ? nulls.replaceFromClient() : encoded;
141
142        Object decoded = toDecode == null ? null : encoder.toValue(toDecode);
143
144        value = decoded;
145    }
146
147    public String getClientId()
148    {
149        if (clientId == null)
150        {
151            clientId = jsSupport.allocateClientId(resources);
152            hiddenInputElement.forceAttributes("id", clientId);
153        }
154
155        return clientId;
156    }
157
158    public String getControlName()
159    {
160        return controlName;
161    }
162}