Struts 2 2.1 and Ajax

2009-08-03
An error in Ajax DWR
When using DWR (struts2.1.6), for example, form or verification, the following errors may sometimes occur:

Freemarker template error!

Expression parameters. parsecontent is undefined on line 45, column 28 in template/ajax/head. FTL.
The problematic instruction:
----------
==>$ {Parameters. parsecontent? String} [on line 45, column 26 in template/ajax/head. FTL]
----------

 

All errors are as follows:

Freemarker template error!

Expression parameters. parsecontent is undefined on line 45, column 28 in template/ajax/head. FTL.
The problematic instruction:
----------
==>$ {Parameters. parsecontent? String} [on line 45, column 26 in template/ajax/head. FTL]
----------

Java backtrace for programmers:
----------
Freemarker. Core. invalidreferenceexception: expression parameters. parsecontent is undefined on line 45, column 28 in template/ajax/head. FTL.
At freemarker. Core. templateobject. assertnonnull (templateobject. Java: 124)
At freemarker. Core. templateobject. invalidtypeexception (templateobject. Java: 134)
At freemarker. Core. builtin $ stringbi. _ getastemplatemodel (builtin. Java: 358)
At freemarker. Core. expression. getastemplatemodel (expression. Java: 89)
At freemarker. Core. expression. getstringvalue (expression. Java: 93)
At freemarker. Core. dollarvariable. Accept (dollarvariable. Java: 76)
At freemarker. Core. environment. Visit (environment. Java: 208)
At freemarker. Core. mixedcontent. Accept (mixedcontent. Java: 92)
At freemarker. Core. environment. Visit (environment. Java: 208)
At freemarker. Core. environment. Process (environment. Java: 188)
At freemarker. template. Template. process (Template. java: 237)
At org. apache. struts2.components. template. FreemarkerTemplateEngine. renderTemplate (FreemarkerTemplateEngine. java: 185)
At org. apache. struts2.components. UIBean. mergeTemplate (UIBean. java: 558)
At org. apache. struts2.components. UIBean. end (UIBean. java: 512)
At org. apache. struts2.views. jsp. ComponentTagSupport. doEndTag (ComponentTagSupport. java: 42)
At org. apache. jsp. web. bbs. quiz_002dajax_jsp. _ jspx_meth_s_005fhead_005f0 (quiz_002dajax_jsp.java: 111)
At org. apache. jsp. web. bbs. quiz_002dajax_jsp. _ jspService (quiz_002dajax_jsp.java: 74)
At org. apache. jasper. runtime. HttpJspBase. service (HttpJspBase. java: 70)
At javax. servlet. http. HttpServlet. service (HttpServlet. java: 803)
At org. apache. jasper. servlet. JspServletWrapper. service (JspServletWrapper. java: 374)
At org. apache. jasper. servlet. JspServlet. serviceJspFile (JspServlet. java: 337)
At org. apache. jasper. servlet. JspServlet. service (JspServlet. java: 266)
At javax. servlet. http. HttpServlet. service (HttpServlet. java: 803)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 290)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. apache. struts2.dispatcher. FilterDispatcher. doFilter (FilterDispatcher. java: 461)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 235)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. apache. struts2.dispatcher. ActionContextCleanUp. doFilter (ActionContextCleanUp. java: 97)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 235)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At share. filter. EncodingFilter. doFilter (EncodingFilter. java: 31)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 235)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. tuckey. web. filters. urlrewrite. RuleChain. handleRewrite (RuleChain. java: 164)
At org. tuckey. web. filters. urlrewrite. RuleChain. doRules (RuleChain. java: 141)
At org. tuckey. web. filters. urlrewrite. UrlRewriter. processRequest (UrlRewriter. java: 90)
At org. tuckey. web. filters. urlrewrite. UrlRewriteFilter. doFilter (UrlRewriteFilter. java: 406)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 235)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. cndoctors. servlet. HibernateFilter. doFilter (HibernateFilter. java: 38)
At org. apache. catalina. core. ApplicationFilterChain. internalDoFilter (ApplicationFilterChain. java: 235)
At org. apache. catalina. core. ApplicationFilterChain. doFilter (ApplicationFilterChain. java: 206)
At org. apache. catalina. core. StandardWrapperValve. invoke (StandardWrapperValve. java: 233)
At org. apache. catalina. core. StandardContextValve. invoke (StandardContextValve. java: 175)
At org. apache. catalina. core. StandardHostValve. invoke (StandardHostValve. java: 128)
At org. apache. catalina. valves. ErrorReportValve. invoke (ErrorReportValve. java: 102)
At org. Apache. Catalina. Core. standardenginevalve. Invoke (standardenginevalve. Java: 109)
At org. Apache. Catalina. connector. coyoteadapter. Service (coyoteadapter. Java: 286)
At org. Apache. Coyote. http11.http11processor. Process (http11processor. Java: 844)
At org. Apache. Coyote. http11.http11protocol $ http11connectionhandler. Process (http11protocol. Java: 583)
At org.apache.tomcat.util.net. jioendpoint $ worker. Run (jioendpoint. Java: 447)
At java. Lang. thread. Run (thread. Java: 595)

 

Solution:

1: Add a struts2-dojo-plugin.jar in the project
2: add

<% @ Taglib prefix = "SX" uri = "/Struts-Dojo-tags" %>

3: Change <s: Head theme = "ajax"/> to <SX: Head/>