DeclarePageInput


1   /*
2    * Copyright 2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   *
16   * $Header:$
17   */
18  package org.apache.beehive.netui.tags.databinding.pageinput;
19  
20  import java.util.Map  ;
21  import javax.servlet.jsp.JspException  ;
22  import javax.servlet.jsp.PageContext  ;
23  import javax.servlet.http.HttpServletRequest  ;
24  
25  import org.apache.beehive.netui.pageflow.internal.InternalUtils;
26  import org.apache.beehive.netui.util.Bundle;
27  import org.apache.beehive.netui.util.logging.Logger;
28  import org.apache.beehive.netui.tags.AbstractSimpleTag;
29  
30  /**
31   * <p>
32   * The DeclarePageInput tag is used to declare variables that are passed as outputs of Page Flow actions to a
33   * JSP.  This allows pages to declare a data contract that invoking actions must satisfy in order to
34   * successfully render a page; in essence, this is a simple method signature for the JSP.
35   * </p>
36   * <p>
37   * Page inputs are added to a Page Flow's {@link org.apache.beehive.netui.pageflow.Forward} class via the
38   * {@link org.apache.beehive.netui.pageflow.Forward#addActionOutput(String, Object)} method.  From the page's
39   * perspective, the action outputs are known as <i>page inputs</i> and are available via the JSP EL
40   * implicit object <code>pageInput</code> using the name given them on the
41   * {@link org.apache.beehive.netui.pageflow.Forward} and set on this tag via {@link #setName(String)}.
42   * </p>
43   * <p>
44   * A page input can be declared to be required; if required, the page input must be available in
45   * the map of action outputs passed to the page.
46   * </p>
47   * <p>
48   * For example, to add an actiout output called <code>profile</code> to a {@link org.apache.beehive.netui.pageflow.Forward}
49   * an action would contain code like:<br/>
50   * <pre>
51   *     forward.addActionOutput("profile", yourProfile);
52   * </pre>
53   * In order to declare this as a page input in a JSP, the page would contain a tag as:
54   * <pre>
55   *     &lt;netui-data:declarePageInput name="profile" type="org.someprofile.ProfileBean"/>
56   * </pre>
57   * and the <code>profile</code> object could be referenced in the JSP as:
58   * <pre>
59   *     ${pageInput.profile}
60   * </pre>
61   * </p>
62   *
63   * @jsptagref.tagdescription
64   * <p>
65   * The DeclarePageInput tag is used to declare variables that are passed as outputs of Page Flow actions to a
66   * JSP.  This allows pages to declare a data contract that invoking actions must satisfy in order to
67   * successfully render a page; in essence, this is a simple method signature for the JSP.
68   * </p>
69   * <p>
70   * Page inputs are added to a Page Flow's {@link org.apache.beehive.netui.pageflow.Forward} class via the
71   * {@link org.apache.beehive.netui.pageflow.Forward#addActionOutput(String, Object)} method.  From the page's
72   * perspective, the action outputs are known as <i>page inputs</i> and are available via the JSP EL
73   * implicit object <code>pageInput</code> using the name given them on the
74   * {@link org.apache.beehive.netui.pageflow.Forward} and set on this tag via {@link #setName(String)}.
75   * </p>
76   * <p>
77   * A page input can be declared to be required; if required, the page input must be available in
78   * the map of action outputs passed to the page.
79   * </p>
80   * <p>
81   * For example, to add an actiout output called <code>profile</code> to a {@link org.apache.beehive.netui.pageflow.Forward}
82   * an action would contain code like:<br/>
83   * <pre>
84   *     forward.addActionOutput("profile", yourProfile);
85   * </pre>
86   * In order to declare this as a page input in a JSP, the page would contain a tag as:
87   * <pre>
88   *     &lt;netui-data:declarePageInput name="profile" type="org.someprofile.ProfileBean"/>
89   * </pre>
90   * and the <code>profile</code> object could be referenced in the JSP as:
91   * <pre>
92   *     ${pageInput.profile}
93   * </pre>
94   * </p>
95   *
96   * @netui:tag name="declarePageInput" body-content="scriptless"
97   *            description="Use this tag to declare a page input variable that is available in the pageInput databinding context."
98   */
99  public class DeclarePageInput
100     extends AbstractSimpleTag {
101 
102     private static final Logger LOGGER = Logger.getInstance(DeclarePageInput.class);
103     private static final String   EMPTY_STRING = "";
104 
105     private String   _type = null;
106     private String   _name = null;
107     private boolean _required = true;
108 
109     /**
110      * Get the name of this tag.  This is used to identify the type of this tag
111      * for reporting tag errors.
112      *
113      * @return a constant String representing the name of this tag.
114      */
115     public String   getTagName() {
116         return "DeclarePageInput";
117     }
118 
119     /**
120      * Set the name of a variable that can be referecned using the page
121      * input data binding context.
122      *
123      * @param name the name of the variable
124      * @jsptagref.attributedescription The name of the variable to reference.
125      * @jsptagref.attributesyntaxvalue <i>string_name</i>
126      * @netui:attribute required="true"
127      */
128     public void setName(String   name) {
129         _name = name;
130     }
131 
132     /**
133      * Set a flag that declares whether this page intput is required or optiona.  If a Page Input is required,
134      * the tag will report an error if the page input key does not appear in the set of page inputs for a page.
135      *
136      * @param required whether to require the page input for the page
137      * @jsptagref.attributedescription
138      * Set a flag that declares whether this page intput is required or optiona.  If a Page Input is required,
139      * the tag will report an error if the page input key does not appear in the set of page inputs for a page.
140      * @jsptagref.attributesyntaxvalue <i>string_name</i>
141      * @netui:attribute required="false"
142      */
143     public void setRequired(boolean required) {
144         _required = required;
145     }
146 
147     /**
148      * Set the String classname variable that represents the expected type of the page input.
149      *
150      * @param type the type of the variable that is referenced
151      * @jsptagref.attributedescription
152      * Set the String classname variable that represents the expected type of the page input.
153      * @jsptagref.attributesyntaxvalue <i>string_type</i>
154      * @netui:attribute required="true"
155      */
156     public void setType(String   type) {
157         _type = type;
158     }
159 
160     /**
161      *
162      */
163     public void doTag()
164         throws JspException   {
165 
166         LOGGER.debug("Added a page input named \"" + _name + "\" of type \"" + _type + "\"");
167 
168         if(_name.equals(EMPTY_STRING)) {
169             String   msg = Bundle.getErrorString("Tags_DeclarePageInput_EmptyName");
170             registerTagError(msg, null);
171         }
172 
173         if(_type.equals(EMPTY_STRING)) {
174             String   msg = Bundle.getErrorString("Tags_DeclarePageInput_EmptyType");
175             registerTagError(msg, null);
176         }
177 
178         if(_required) {
179             assert getJspContext() instanceof PageContext  ;
180             assert ((PageContext  )getJspContext()).getRequest() instanceof HttpServletRequest  ;
181 
182             HttpServletRequest   request = (HttpServletRequest  )((PageContext  )getJspContext()).getRequest();
183             Map   actionOutputMap = InternalUtils.getPageInputMap(request);
184             if(actionOutputMap == null || !actionOutputMap.containsKey(_name)) {
185                 String   msg = Bundle.getErrorString("Tags_DeclarePageInput_Required", new Object  []{_name});
186                 registerTagError(msg, null);
187             }
188         }
189 
190         if(hasErrors())
191             reportErrors();
192     }
193 }
194
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