src/site/apt/tutorial/integration/velocity.apt

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         -----------
         Integration with Apache Velocity
         -----------

Integration with Apache Velocity

  {{{http://velocity.apache.org/}Apache Velocity}} is a templating framework
  that can be used as a replacement for JavaServer Pages (JSP). Tiles can be
  used with Velocity through the use of Tiles Velocity package.

* Configuration

  To use Velocity together with Tiles

  * Add Velocity (1.7 or better) and Velocity Tools (2.0 or better) jars to your application.

  * Add <<<tiles-template-x.x.x.jar>>> and <<<tiles-velocity-x.x.x.jar>>> files
  to your application.
  * Add this code in you <<<velocity.properties>>> file:

----------------------------------
userdirective=org.apache.tiles.velocity.template.AddAttributeDirective,\
  org.apache.tiles.velocity.template.AddListAttributeDirective,\
  org.apache.tiles.velocity.template.DefinitionDirective,\
  org.apache.tiles.velocity.template.GetAsStringDirective,\
  org.apache.tiles.velocity.template.ImportAttributeDirective,\
  org.apache.tiles.velocity.template.InsertAttributeDirective,\
  org.apache.tiles.velocity.template.InsertDefinitionDirective,\
  org.apache.tiles.velocity.template.InsertTemplateDirective,\
  org.apache.tiles.velocity.template.PutAttributeDirective,\
  org.apache.tiles.velocity.template.PutListAttributeDirective
----------------------------------


  * To access ".vm" files from HTTP requests, add this piece of configuration in <<<web.xml>>>
  (the parameters can be modified as needed).

----------------------------------
<servlet>
  <servlet-name>velocity</servlet-name>
  <servlet-class>org.apache.velocity.tools.view.VelocityViewServlet</servlet-class>

  <init-param>
    <param-name>org.apache.velocity.toolbox</param-name>
    <param-value>/WEB-INF/tools.xml</param-value>
  </init-param>

  <init-param>
    <param-name>org.apache.velocity.properties</param-name>
    <param-value>/WEB-INF/velocity.properties</param-value>
  </init-param>
</servlet>
----------------------------------

  * To access ".vm" files as attributes, register VelocityAttributeRenderer
  this way (only available in a servlet environment):

----------------------------------
@Override
protected void registerAttributeRenderers(
        BasicRendererFactory rendererFactory, TilesApplicationContext applicationContext,
        TilesRequestContextFactory contextFactory,
        TilesContainer container, AttributeEvaluator evaluator) {
    super.registerAttributeRenderers(rendererFactory, applicationContext, contextFactory,
            container, evaluator);

    VelocityAttributeRenderer velocityRenderer = new VelocityAttributeRenderer();
    velocityRenderer.setApplicationContext(applicationContext);
    velocityRenderer.setEvaluator(evaluator);
    velocityRenderer.setRequestContextFactory(contextFactory);
    velocityRenderer.setParameter("org.apache.velocity.toolbox", "/WEB-INF/tools.xml");
    velocityRenderer.setParameter("org.apache.velocity.properties", "/WEB-INF/velocity.properties");
    velocityRenderer.commit();
    rendererFactory.registerRenderer("velocity", velocityRenderer);
}
----------------------------------

  This way you can specify an attribute that is rendered directly using this syntax:

----------------------------------
<put-attribute name="myAttribute" value="/pages/myPage.vm" type="velocity" />
----------------------------------

* Usage in Velocity templates

  There are two ways to use Tiles-Velocity integration:

  * the <<<tiles>>> tool, that is a Velocity-style tool:

----------------------------------
$tilesAlt.startAttributeContext()
$set($templateAttribute = $tilesAlt.createTemplateAttribute("/page/myTemplate.vm"))
$set($attributeContext = $tilesAlt.getAttributeContext())
  $set($attribute = $tilesAlt.createAttribute())
  $attribute.setValue("This is the title.")
  $attributeContext.putAttribute("title", $attribute})

  $set($attribute = $tilesAlt.createAttribute())
  $attribute.setValue("/velocity/header.vm")
  $attribute.setRenderer("velocity")
  $attributeContext.putAttribute("header", $attribute})

  $set($attribute = $tilesAlt.createAttribute())
  $attribute.setValue("/velocity/body.vm")
  $attribute.setRenderer("velocity")
  $attributeContext.putAttribute("body", $attribute})

$tilesAlt.render($templateAttribute)
$tilesAlt.endAttributeContext()
----------------------------------

  * the <<<tiles>>> directives, that have a tag-like meaning.

----------------------------------
#tiles_insertTemplate({"template":"/page/myTemplate.vm"})
  #tiles_putAttribute({"name":"title", "value":"This is the title."})#end
  #tiles_putAttribute({"name":"header", "value":"/velocity/header.vm", "type":"velocity"})#end
  #tiles_putAttribute({"name":"body", "value":"/velocity/body.vm", "type":"velocity"})#end
#end
----------------------------------

  Other <<<tiles>>> directives are:
  
      * <<<getAsString(String attributeName)>>> - get the value of named attribute as string.

      * <<<importAttribute(String attributeName, String toName)>>> - import the named attribute into the scope of
  	template context under the (optional) custom name.

      * <<<insertAttribute(String attributeName)>>> - inserts given attribute in the output in its own context.
        If this is a string a string is printed, if this is a definition - it is included in the output.

      * <<<insertAttribute(String attributeName, boolean ownContext)>>> - inserts given attribute in the output.
        If this is a string a string is printed, if this is a definition - it is included in the output. You can specify whether
        a separate context is created for rendering the definition - in this case variables with duplicate names
        will not be inherited from the parent definition

      * <<<insertDefinition(String definitionName)>>> - renders a definition in its own context.

      * <<<insertDefinition(String definitionName, boolean ownContext)>>> - inserts definition, optionally in the shared context.

      * <<<insertTemplate(String template)>>> - inserts a named page, equivalent to Velocity's <<<#parse>>>.


  For details about the tool and directives see the {{{../../apidocs/index.html}Javadocs}}.