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From da...@cocoon.zones.apache.org
Subject [DAISY] Updated: Template Transformer
Date Sun, 23 Oct 2005 15:43:17 GMT
A document has been updated:

http://cocoon.zones.apache.org/daisy/documentation/475.html

Document ID: 475
Branch: main
Language: default
Name: Template Transformer (previously Cocoon Forms: Template Transformer)
Document Type: Cocoon Document (unchanged)
Updated on: 10/23/05 3:43:04 PM
Updated by: Bruno Dumon

A new version has been created, state: publish

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    <h1>Introduction</h1>
    
--- <p>The FormsTemplateTransformer (simply "forms transformer" from now on) makes
--- it possible to define the layout for your form without having to write a
--- separate XSLT for each form. If you prefer to do everything with XSLT, you have
--- also the option of using the <a href="daisy:476">FormsGenerator</a>. In general
--- we recommend to use the forms transformer though.</p>
+++ <p>The Forms Template Transformer can execute the <a href="daisy:755">CForms
+++ template</a> tags.</p>
    
--- <p>The basic principle is that the forms transformer will replace any
--- &lt;ft:widget id="xyz"/&gt; elements it encounters by the XML representation of
--- the corresponding widgets. These ft:widget elements can be embedded in e.g. a
--- HTML layout. So after passing this template through the forms transformer you'll
--- end up with HTML with here and there a piece of XML describing a widget. This
--- XML description contains all state information of the widget: its value,
--- validation errors, selection-list data if any, and so on. These
--- widget-XML-descriptions will then typically be translated to HTML by an XSLT.
--- This XSLT is then however not form-specific, as it simply needs to know how to
--- translate individual widgets to HTML, and does not have to create the complete
--- page layout. CForms contains just such an XSLT so you don't have to write it
--- yourself (except if you need to do heavy customisation). The image below
--- illustrates this process.</p>
+++ <h1>Special features of the forms transformer</h1>
    
--- <p align="center"><img src="daisy:405"/></p>
--- 
    <h2>Where the forms transformer looks for the form instance object</h2>
    
--- <p>Each time the forms transformer encounters a ft:form-template element (see
--- further on), it will try to retrieve a CForms form instance object. It looks for
--- it in the following locations:</p>
+++ <p>Each time the forms transformer encounters a ft:form-template element, it
+++ will try to retrieve a CForms form instance object. It looks for it in the
+++ following locations:</p>
    
    <ol>
    <li>if the ft:form-template element has a location attribute, then the value of
(12 equal lines skipped)
    <p>If the form is not found at any of these locations, an exception is thrown.
    </p>
    
--- <h1>Forms transformer element reference</h1>
--- 
--- <p>The elements to which the forms transformer reacts are all in the "ft" (Forms
--- Template) namespace, which is identified by the following URI:</p>
--- 
--- <pre>http://apache.org/cocoon/forms/1.0#template</pre>
--- 
--- <p>These will generally be replaced by elements in the "fi" (Forms Instance)
--- namespace, which is identified by the following URI:</p>
--- 
--- <pre>http://apache.org/cocoon/forms/1.0#instance</pre>
--- 
--- <h2>ft:form-template</h2>
--- 
--- <p>The ft:form-template element is always required; all other ft:* elements
--- should occur inside a ft:form-template element. As described earlier, when the
--- forms transformer encounters the ft:form-template element it will try to look up
--- the form instance object.</p>
--- 
--- <p>ft:form-template elements may not be nested.</p>
--- 
--- <p>The ft:form-template will by default copy over all attributes appearing on
--- it, except for one attribute called "location", and it will also take special
--- care of the action attribute.</p>
--- 
--- <p>The <strong>action</strong> attribute can contain JXPath expressions.
As with
--- the JXTemplateGenerator, these JXPath expressions must be embedded inside #{ and
--- }. By allowing the use of JXPath expressions, you can embed dynamic data in the
--- action attribute. One of the most common uses is to embed the continuation id
--- (if you're using flowscript), for example:</p>
--- 
--- <pre>&lt;ft:form-template action="#{$cocoon/continuation/id}.continue" ...</pre>
--- 
--- <p>The following objects are available in the JXPath context via the cocoon
--- object: continuation, requests, session and parameters. The context of the
--- JXPath expression is the map passed on from the flowscript (if any).</p>
--- 
--- <p>The <strong>location</strong> attribute, if present, is used to retrieve
the
--- form instance object. The value of the location attribute should be a JXPath
--- expression, and is executed in the same context as the JXPath expressions
--- embedded in the action attribute.</p>
--- 
    <p>For example, if your form object is stored in the session using the key
    "myform", then following expression in the location attribute can be used to
    retrieve it:</p>
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    attribute, this can be used to handle multiple forms occuring on one template.
    </p>
    
--- <h2>ft:widget</h2>
+++ <h1>Action attribute on ft:form-template</h1>
    
--- <p>The ft:widget element is replaced by the forms transformer by the XML
--- representation of a widget. Which widget is specified by the id attribute. The
--- ft:widget element can contain a fi:styling element containing parameters to
--- influence the styling process (the XSLT). The forms transformer will simply copy
--- the fi:styling element over to its output.</p>
+++ <p>The forms transformer supports the execution of JXPath expressions that occur
+++ in the action attribute of the ft:form-template element. This makes it possible
+++ to embed the continuation ID in that attribute.</p>
    
    <p>For example:</p>
    
--- <pre>&lt;ft:widget id="pass"&gt;
---   &lt;fi:styling type="password"/&gt;
--- &lt;ft:widget/&gt;</pre>
+++ <pre>&lt;ft:form-template action="#{$cocoon/continuation/id}.continue" ...</pre>
    
--- <p>will be replaced by:</p>
+++ <p>The following objects are available in the JXPath context via the cocoon
+++ object: continuation, requests, session and parameters. The context of the
+++ JXPath expression is the map passed on from the flowscript (if any).</p>
    
--- <pre>&lt;fi:field id="pass"&gt;
---   [... label, validation errors, ...]
---   &lt;fi:styling type="password"/&gt;
--- &lt;/fi:field&gt;</pre>
+++ <p>Note that the JXTemplate-based form-template-tag-implementation of course
+++ also supports this, as this is a native feature of JXTemplate.</p>
    
--- <h2>ft:widget-label</h2>
--- 
--- <p>The ft:widget-label element will be replaced by the forms transformer with
--- the label of a certain widget (specified by an id attribute). The label will not
--- be wrapped in another element.</p>
--- 
--- <h2>ft:continuation-id</h2>
--- 
--- <p>The ft:continuation-id element will be replaced by the forms transformer by:
--- </p>
--- 
--- <pre>&lt;fi:continuation-id&gt;
---   ID-of-the current-continuation
--- &lt;/fi:continuation-id&gt;</pre>
--- 
--- <p>This might be useful for embedding the continuation ID in a hidden form
--- field, for example.</p>
--- 
--- <h2>Working with repeaters: ft:repeater-widget, ft:repeater-widget-label,
--- ft:repeater-size</h2>
--- 
--- <p>The ft:repeater-widget element is similar to the ft:widget element but
--- provides special treatment for repeaters. The content of the ft:repeater-widget
--- element will be used as a template to generate each of the rows of the repeater.
--- </p>
--- 
--- <p>The ft:repeater-widget-label element is used to retrieve the label of a
--- widget contained by a repeater. It requires two attributes: id (identifying the
--- repeater) and widget-id (identifying the widget in the repeater).</p>
--- 
--- <p>The ft:repeater-size element inserts an element &lt;fi:repeater-size id="..."
--- size="..."/&gt; containing the size (number of rows) of the repeater.</p>
--- 
--- <p>For an example of how this all fits together, take a look at the samples
--- included in the forms block.</p>
--- 
    </body>
    </html>


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