Please make sure you have read the Tag Syntax document and understand how tag attribute syntax works.
This tag can be used to parameterize other tags. The include
tag and bean
tag are examples of such tags.
The parameters can be added with or without a name
as key. If the tag provides a name
attribute the parameters are added using the Component#addParameter(String, Object)
method. For unnamed parameters the tag must implement the UnnamedParametric
interface defined in this class (e.g. The TextTag does this).
This tag has the following two parameters.
NOTE: When you declare the param tag, the value can be defined in either a
value
attribute or as text between the start and end tag. Struts behaves a bit different according to these two situations. This is best illustrated using an example:<param name="color">blue</param>
(A)<param name="color" value="blue"/>
(B) In the first situation (A) the value would be evaluated to the stack as ajava.lang.String
object. And in situation (B) the value would be evaluated to the stack as ajava.lang.Object
object. For more information see WW-808.
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/param-description.html %}
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/param-attributes.html %}
<ui:component> <ui:param name="key" value="[0]"/> <ui:param name="value" value="[1]"/> <ui:param name="context" value="[2]"/> </ui:component>
Whether to suppress empty parameters:
<s:url action="eventAdd"> <s:param name="bean.searchString" value="%{bean.searchString}" /> <s:param name="bean.filter" value="%{bean.filter}" /> <s:param name="bean.pageNum" value="%{pager.pageNumber}" suppressEmptyParameters="true" /> </s:url>
where the key will be the identifier and the value the result of an OGNL expression run against the current ValueStack.