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Posted to docs@cocoon.apache.org by da...@cocoon.zones.apache.org on 2007/06/07 20:06:33 UTC

[DAISY] Updated: Tags

A document has been updated:

http://cocoon.zones.apache.org/daisy/documentation/511.html

Document ID: 511
Branch: main
Language: default
Name: Tags (previously Advanced Control Flow - JXTemplate)
Document Type: Cocoon Document (unchanged)
Updated on: 6/7/07 6:06:10 PM
Updated by: Reinhard Pötz

A new version has been created, state: publish

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--- <h1>JXTemplate Generator</h1>
--- 
--- <p>The JXTemplate Generator is a page template processor that allows you to
--- inject data from Java and JavaScript objects passed by a Cocoon Flowscript into
--- a Cocoon pipeline. It provides a set of tags (similar to the
--- <a href="http://java.sun.com/products/jsp/jstl/">JSTL</a> core tags) that allow
--- you to iterate over Java collections (and Java or JavaScript arrays) and to test
--- for the presence of optional or alternate bean properties, as well as embedded
--- expressions to specify conditions and to access the properties of objects. The
--- <em>JX</em>Template Generator gets its name from the embedded expression
--- languages it supports, namely
--- <a href="http://jakarta.apache.org/commons/jxpath">Apache <em>JX</em>Path</a>
--- and <a href="http://jakarta.apache.org/commons/jexl">Apache
--- <em>J</em>e<em>X</em>l</a>.</p>
--- 
--- <p>To use the JXTemplate Generator, add a generator entry to your
--- <a href="daisy:580">sitemap</a> with the <tt>src</tt> attribute set to
--- <tt>org.apache.cocoon.generation.JXTemplateGenerator</tt>, for example like
--- this:</p>
--- 
--- <pre>&lt;map:generators&gt;
---   &lt;map:generator label="content,data" 
---       logger="sitemap.generator.jx" name="jx" 
---          src="org.apache.cocoon.generation.JXTemplateGenerator"/&gt;
--- &lt;/map:generators&gt;
--- </pre>
--- 
--- <h1>Expression Languages</h1>
--- 
--- <p>The JXTemplate Generator supports two embedded expression languages:
--- <a href="http://jakarta.apache.org/commons/jexl">Jexl</a> and
--- <a href="http://jakarta.apache.org/commons/jxpath">JXPath</a>. Apache
--- <a href="http://jakarta.apache.org/commons/jexl">Jexl</a> provides an extended
--- version of the expression language of the
--- <a href="http://java.sun.com/webservices/docs/1.0/tutorial/doc/JSTL.html">JSTL</a>.
--- Apache <a href="http://jakarta.apache.org/commons/jxpath">JXPath</a> provides an
--- interpreter of the <a href="http://www.w3.org/TR/xpath">XPath</a> expression
--- language that can apply XPath expressions to graphs of Java objects of all
--- kinds: JavaBeans, Maps, Servlet contexts, DOM etc, including mixtures thereof.
--- </p>
--- 
--- <p>Having an embedded expression language allows a page author to access an
--- object using a simple syntax such as</p>
--- 
--- <pre>&lt;site signOn="${accountForm.signOn}"&gt;
--- </pre>
--- 
--- <p>Embedded Jexl expressions are contained in <tt>${}</tt>.</p>
--- 
--- <p>Embedded JXPath expressions are contained in <tt>#{}</tt>.</p>
--- 
--- <p>The referenced objects may be Java Beans, DOM, or JavaScript objects from a
--- Flowscript. In addition, a special <tt>cocoon</tt> object providing access to
--- the Cocoon <a href="daisy:518#FOM">FOM</a> is available as both a JXPath and
--- Jexl variable in a template.</p>
--- 
--- <p>The <tt>cocoon</tt> object contains the following properties:</p>
--- 
--- <ul>
--- <li><a href="daisy:518#request">request</a>: <br/>
--- The current Cocoon request</li>
--- <li><a href="daisy:518#session">session</a>: <br/>
--- The user session associated with the current request</li>
--- <li><a href="daisy:518#context">context</a>: <br/>
--- The Cocoon context associated with the current request</li>
--- <li><tt>parameters</tt>: <br/>
--- A map containing the parameters passed to the generator in the pipeline</li>
--- <li><a href="daisy:518#WebContinuation">continuation</a>: <br/>
--- The current Web Continuation from your Flowscript</li>
--- </ul>
--- 
--- <p>Jexl Example:</p>
--- 
--- <pre>The content type of the current request is ${cocoon.request.contentType}
--- </pre>
--- 
--- <p>JXPath Example:</p>
--- 
--- <pre>The content type of the current request is #{$cocoon/request/contentType}
--- </pre>
--- 
--- <p>You would typically access the <tt>id</tt> of the Web Continuation:</p>
--- 
--- <pre>&lt;form action="${cocoon.continuation.id}"&gt;
--- </pre>
--- 
--- <p>You can also reach previous continuations via its <tt>parent</tt> property:
--- </p>
--- 
--- <pre>&lt;form action="${cocoon.continuation.parent.id}" &gt;
--- </pre>
--- 
--- <p>or using an XPath expression:</p>
--- 
--- <pre>&lt;form action="#{$cocoon/continuation/parent/id}" &gt;
--- </pre>
--- 
--- <p>Deprecated Variables:</p>
--- 
--- <p>The following variables are deprecated but still supported:</p>
--- 
--- <ul>
--- <li>
--- <a href="file:/home/daisy/tmpdocimport/documentation/apidocs/org/apache/cocoon/environment/Request.html">org.apache.cocoon.environment.Request</a>
--- <tt>request</tt>: <br/>
--- The current Cocoon request (deprecated: use <tt>cocoon.request</tt> instead)
--- </li>
--- <li>
--- <a href="file:/home/daisy/tmpdocimport/documentation/apidocs/org/apache/cocoon/environment/Session.html">org.apache.cocoon.environment.Session</a>
--- <tt>session</tt>: <br/>
--- The current user session (deprecated: use <tt>cocoon.session</tt> instead)</li>
--- <li>
--- <a href="file:/home/daisy/tmpdocimport/documentation/apidocs/org/apache/cocoon/environment/Context.html">org.apache.cocoon.environment.Context</a>
--- <tt>context</tt>: <br/>
--- The current context (deprecated: use <tt>cocoon.context</tt> instead)</li>
--- <li>
--- <a href="file:/home/daisy/tmpdocimport/documentation/apidocs/org/apache/cocoon/components/flow/WebContinuation.html">org.apache.cocoon.components.flow.WebContinuation</a>
--- <tt>continuation</tt>: <br/>
--- The current Web Continuation (deprecated: use <tt>cocoon.continuation</tt>
--- instead)</li>
--- </ul>
--- 
--- <p class="note">When used inside flow, JXTemplate has access to Java and can
--- therefore evaluate expressions like "java.util.Date()" or "java.util.HashMap()".
--- This does <strong>NOT</strong> work when JXTemplates are used without flow. Some
--- symptoms:<br/>
--- [*&lt;jx:out value="${java.util.Date()"/&gt;*] results in [**]</p>
--- 
--- <p class="note">&lt;jx:formatDate value="${java.util.Date()}"
--- pattern="yyyyMMdd"/&gt; results in 'Cannot format given Object as a Date'</p>
--- 
--- <h1>Parameters</h1>
--- 
--- <h2>lenient-xpath</h2>
--- 
--- <p>By default XPath evaluation throws an exception if the supplied XPath does
--- not map to an existing property. This constraint can be relaxed by setting the
--- parameter <tt>lenient-xpath</tt> to <tt>true</tt>. In the lenient mode
--- evaluation simply returns null if the path maps to nothing.</p>
--- 
--- <p>Example:</p>
--- 
--- <pre>    &lt;map:match pattern="*.jx"&gt;
---       &lt;map:generate type="jx" src="documents/{1}.jx"&gt;
---            &lt;map:parameter name="lenient-xpath" value="true"/&gt;
---       &lt;/map:generate&gt;
---       &lt;map:serialize type="xhtml"/&gt;
---     &lt;/map:match&gt;
--- </pre>
--- 
--- <h1>Tags</h1>
--- 
    <p>The JXTemplate Generator tags are defined in the namespace</p>
    
    <pre>http://apache.org/cocoon/templates/jx/1.0
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