struts-logic-el.tld

Apache struts-1.3.10 a stable version

<?xml version="1.0" encoding="UTF-8"?>
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    $Id: struts-logic-el.tld 577190 2007-09-19 08:03:39Z apetrelli $

    Licensed to the Apache Software Foundation (ASF) under one or more
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    The ASF licenses this file to You under the Apache License, Version 2.0
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         http://www.apache.org/licenses/LICENSE-2.0
   
    Unless required by applicable law or agreed to in writing, software
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<!DOCTYPE taglib PUBLIC
        "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
        "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
    <tlib-version>1.3</tlib-version>
    <jsp-version>1.2</jsp-version>
    <short-name>logic</short-name>
    <uri>http://struts.apache.org/tags-logic-el</uri>
    <description>
        <![CDATA[

   <p>This tag library contains tags that are useful in managing conditional
   generation of output text, looping over object collections for repetitive
   generation of output text, and application flow management.</p>
   
   <p>For tags that do value comparisons (equal, greaterEqual, 
   greaterThan, lessEqual, lessThan, notEqual), the following rules apply:</p>
   
   <ul>
   
   <li>The specified value is examined. If it can be converted successfully to a
   double or a long, it is assumed that the ultimate comparison will be numeric
   (either floating point or integer). Otherwise, a String comparison will be
   performed.</li>
   
      <li>The variable to be 
      compared to is retrieved, based on the selector
      attribute(s) (cookie, header, name, parameter, property)
      present on this tag.  It will be converted to the appropriate type
      for the comparison, as determined above.</li>
      
   <li>If the specified variable or property returns null, it will be
      coerced to a zero-length string before the comparison occurs.</li>
      
   <li>The specific comparison for this tag will be performed, and the nested
      body content of this tag will be evaluated if the comparison returns
      a true result.</li>
      
   </ul>
   
   <p> For tags that do substring matching (match, notMatch), the following
   rules apply:</p>
  
  <ul>
  
  <li>The specified variable is retrieved, based on the selector attribute(s)
  (cookie, header, name, parameter, property) present on this tag.</li>
      
  <li>The variable is converted to a String, if necessary.A request time
  exception will be thrown if the specified variable cannot be retrieved, or has
  a null value.</li>
      
  <li>The specified value is checked for existence as a substring of the
  variable, in the position specified by the location attribute, as follows: at
  the beginning (if location is set to start), at the end (if location is set to
  end), or anywhere (if location is not specified).</li>
  
  </ul>
  
  <p>Many of the tags in this tag library will throw a JspException at runtime
  when they are utilized incorrectly (such as when you specify an invalid
  combination of tag attributes). JSP allows you to declare an "error page" in
  the &lt;%@ page %&gt; directive. If you wish to process the actual exception
  that caused the problem, it is passed to the error page as a request attribute
  under key org.apache.struts.action.EXCEPTION.</p>
  
  <p>Struts-logic tags NOT implemented.</p>
  
  <p>This library, a derivation of the normal "struts-logic" library, provides
  the functionality of the Struts logic tags, but assumes the presence of the
  JavaServer Pages Standard Library (JSTL), and uses the JSTL expression engine
  (hereafter abbreviated in many places as just "el") to evaluate attribute
  values instead of using JSP runtime expressions (sometimes called
  "rtexprvalues").</p>

   <p>Because it is assumed this library will be used with the JSTL and the new
   EL engine, there are some tags in the struts-logic library which provide
   functionality which is entirely subsumed by the JSTL. This section lists each
   struts-logic tag which is NOT implemented in the struts-logic-el library, and
   describes the JSTL tag which can be used instead of the Struts
   tag.Struts-Logic TagJSTL Tag</p>

   <p><code>&lt;logic:empty&gt;</code></p>
   
   <p>This functionality is subsumed by the JSTL &lt;c:if>, &lt;c:when> tags and
   the empty function in the JSTL EL.</p>

   <p>Example: &lt;c:if test="${empty var}">CONTENT&lt;/c:if></p>
     
     ]]>
    </description>
    <tag>
        <name>forward</name>
        <tag-class>org.apache.strutsel.taglib.logic.ELForwardTag</tag-class>
        <body-content>empty</body-content>
        <description>
            <![CDATA[
            <p><strong>
    Forward control to the page specified by the specified ActionForward
    entry.
    </strong></p>
          <p>Performs a <code>PageContext.forward()</code> or
    <code>HttpServletResponse.sendRedirect()</code> call for the global
    <code>ActionForward</code> entry for the specified name.  URL
    rewriting will occur automatically if a redirect is performed.</p>
      ]]>
        </description>
        <attribute>
            <name>name</name>
            <required>true</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>
      	The logical name of the global <code>ActionForward</code> entry
      	that identifies the destination, and forwarding approach, to be used.
        <strong>Note</strong>: forwarding to Tiles definitions is not supported
        from this tag.  You should forward to them from an Action subclass.
      </p>
         ]]>
            </description>
        </attribute>
    </tag>
    <tag>
        <name>iterate</name>
        <tag-class>org.apache.strutsel.taglib.logic.ELIterateTag</tag-class>
        <tei-class>org.apache.struts.taglib.logic.IterateTei</tei-class>
        <body-content>JSP</body-content>
        <description>
            <![CDATA[
            <p><strong>
    Repeat the nested body content of this tag over a specified collection.
    </strong></p>
          <p>Repeats the nested body content of this tag once for every element
    of the specified collection, which must be an <code>Iterator</code>,
    a <code>Collection</code>, a <code>Map</code> (whose values are to be
    iterated over), or an array.  The collection to be iterated over must be
    specified in one of the following ways:</p>
         <ul>
            <li>As a runtime expression specified as the value of the
        <code>collection</code> attribute.</li>
            <li>As a JSP bean specified by the <code>name</code> attribute.</li>
            <li>As the property, specified by the <code>property</code>, of the
        JSP bean specified by the <code>name</code> attribute.</li>
         </ul>
         <p>The collection to be iterated over MUST conform to one of the following
    requirements in order for iteration to be successful:</p>
         <ul>
            <li>An array of Java objects or primitives.</li>
            <li>An implementation of <code>java.util.Collection</code>, including
        <code>ArrayList</code> and <code>Vector</code>.</li>
            <li>An implementation of <code>java.util.Enumeration</code>.</li>
            <li>An implementation of <code>java.util.Iterator</code>.</li>
            <li>An implementation of <code>java.util.Map</code>, including
        <code>HashMap</code>, <code>Hashtable</code>, and
        <code>TreeMap</code>.  <strong>NOTE</strong> - See below for
        additional information about accessing Maps.</li>
         </ul>
         <p>Normally, each object exposed by the iterate tag is an element
    of the underlying collection you are iterating over.  However, if you
    iterate over a <code>Map</code>, the exposed object is of type
    <code>Map.Entry</code> that has two properties:</p>
         <ul>
            <li>
               <code>key</code> - The key under which this item is stored in the
        underlying Map.</li>
            <li>
               <code>value</code> - The value that corresponds to this key.</li>
         </ul>
         <p>So, if you wish to iterate over the values of a Hashtable, you would
    implement code like the following:</p>
         <code>&lt;logic-el:iterate id="element" name="myhashtable"><br/>
      Next element is &lt;bean:write name="element" property="value"/><br/>
    &lt;/logic-el:iterate>
    </code>
         <p>If the collection you are iterating over can contain <code>null</code>
    values, the loop will still be performed but no page scope attribute
    (named by the <code>id</code> attribute) will be created for that loop
    iteration.  You can use the <code>&lt;logic-el:present;gt;</code> and
    <code>&lt;logic-el:notPresent&gt;</code> tags to test for this case.</p>
      ]]>
        </description>
        <attribute>
            <name>collection</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>A runtime expression that evaluates to a collection (conforming to
      the requirements listed above) to be iterated over.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>id</name>
            <required>true</required>
            <rtexprvalue>false</rtexprvalue>
            <description>
                <![CDATA[
            <p>The name of a page scope JSP bean that will contain the current
      element of the collection on each iteration, if it is not
      <code>null</code>.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>indexId</name>
            <required>false</required>
            <rtexprvalue>false</rtexprvalue>
            <description>
                <![CDATA[
            <p>The name of a page scope JSP bean that will contain the current
      index of the collection on each iteration.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>length</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>The maximum number of entries (from the underlying collection) to be
      iterated through on this page.  This can be either an integer that
      directly expresses the desired value, or the name of a JSP bean (in
      any scope) of type <code>java.lang.Integer</code> that defines the
      desired value.  If not present, there will be no limit on the number
      of iterations performed.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>name</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>The name of the JSP bean containing the collection to be iterated
      (if <code>property</code> is not specified), or the JSP bean whose
      property getter returns the collection to be iterated (if
      <code>property</code> is specified).</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>offset</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>The zero-relative index of the starting point at which entries from
      the underlying collection will be iterated through.  This can be either
      an integer that directly expresses the desired value, or the name of a
      JSP bean (in any scope) of type <code>java.lang.Integer</code> that
      defines the desired value.  If not present, zero is assumed (meaning
      that the collection will be iterated from the beginning.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>property</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>Name of the property, of the JSP bean specified by <code>name</code>,
      whose getter returns the collection to be iterated.</p>
         ]]>
            </description>
        </attribute>
        <attribute>
            <name>scope</name>
            <required>false</required>
            <rtexprvalue>true</rtexprvalue>
            <description>
                <![CDATA[
            <p>The bean scope within which to search for the bean named by the
      <code>name</code> property, or "any scope" if not specified.</p>
         ]]>
            </description>
        </attribute>