---

layout: default title: component tag parent: title: Tag Reference url: tag-reference.html

component

Please make sure you have read the Tag Syntax document and understand how tag attribute syntax works.

Description

Renders an custom UI widget using the specified templates. Additional objects can be passed in to the template using the param tags.

{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/component-description.html %}

Freemarker:

Objects provided can be retrieve from within the template via $parameters._paramname_.

JSP:

Objects provided can be retrieve from within the template via <s:property value="%{parameters._paramname_}" />

In the bottom JSP and Velocity samples, two parameters are being passed in to the component. From within the component, they can be accessed as:

Freemarker:

$parameters.get('key1') and $parameters.get('key2') or $parameters.key1 and $parameters.key2

JSP:

<s:property value="%{parameters.key1}" /> and <s:property value="%{'parameters.key2'}" /> or <s:property value="%{parameters.get('key1')}" /> and <s:property value="%{parameters.get('key2')}" />

Currently, your custom UI components can be written in Velocity, JSP, or Freemarker, and the correct rendering engine will be found based on file extension.

Remember: the value params will always be resolved against the ValueStack so if you mean to pass a string literal to your component, make sure to wrap it in single quotes i.e. value="'value1'" (note the opening "' and closing '" otherwise, the value stack will search for an Object on the stack with a method of getValue1().

If JSP is used as the template, the JSP template itself must lie within the webapp itself and not the classpath. Unlike Freemarker or Velocity, JSP template could not be picked up from the classpath.

(!) templateDir and theme attribute

The final path to the template will be built using the templateDir and template attributes, like ${templateDir}/${theme}/${template}. If for example your component is under /components/html/option.jsp, you would have to set templateDir=“components”, theme=“html” and template=“options.jsp”.

For any Struts tag that you use in your component, make sure that you set its templateDir=“template”

Attributes

{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/component-attributes.html %}

Examples

JSP

<s:component template="/my/custom/component.jsp"/>

or

<s:component template="/my/custom/component.jsp">
    <s:param name="key1" value="value1"/>
    <s:param name="key2" value="value2"/>
</s:component>

Velocity

#s-component( "template=/my/custom/component.vm" )

or

#s-component( "template=/my/custom/component.vm" )
    #s-param( "name=key1" "value=value1" )
    #s-param( "name=key2" "value=value2" )
#end

Freemarker

<@s..component template="/my/custom/component.ftl" />

or

<@s.component template="/my/custom/component.ftl">
    <@s.param name="key1" value="%{'value1'}" />
    <@s.param name="key2" value="%{'value2'}" />
</@s.component>