Struts 2 s:select tag list property populate

action class:
package mystuff.action;

import java.util.List;

import mystuff.model.Person;
import mystuff.service.PersonService;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.Preparable;

public class PersonAction implements Preparable {
      private PersonService service;
      private List<Person> persons;
      private Person person;
      private Integer id;
      
      public PersonAction(PersonService service) {
            this.service = service;
      }
      
      public String execute() {
            this.persons = service.findAll();
            return Action.SUCCESS;
      }
      
      public String save() {
            this.service.save(person);
            this.person = new Person();
            return execute();
      }
      
      public String remove() {
            service.remove(id);
            return execute();
      }
      
      
      public void prepare() throws Exception {
            if (id != null) {
                  person = service.find(id);
            }
            
      }
      
      public List<Person> getPersons() {
            return persons;
      }
      
      public Person getPerson() {
            return person;
      }

      public void setPerson(Person person) {
            this.person = person;
      }

      public Integer getId() {
            return id;
      }

      public void setId(Integer id) {
            this.id = id;
      }
      
      
      
}


Error message:
SEVERE: Servlet.service() for servlet jsp threw exception
tag 'select', field 'list', name 'owners': The requested list key 'persons' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
      at org.apache.struts2.components.Component.fieldError(Component.java:231)
      at org.apache.struts2.components.Component.findValue(Component.java:293)
      at org.apache.struts2.components.ListUIBean.evaluateExtraParams(ListUIBean.java:79)
      at org.apache.struts2.components.Select.evaluateExtraParams(Select.java:99)
      at org.apache.struts2.components.UIBean.evaluateParams(UIBean.java:780)
      at org.apache.struts2.components.UIBean.end(UIBean.java:481)
      at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:43)
      at org.apache.jsp.index_jsp._jspx_meth_s_005fselect_005f0(index_jsp.java:734)
      at org.apache.jsp.index_jsp._jspx_meth_s_005fform_005f1(index_jsp.java:599)
      at org.apache.jsp.index_jsp._jspService(index_jsp.java:191)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
      at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:414)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
      at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:870)
      at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
      at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
      at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
      at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:685)
      at java.lang.Thread.run(Thread.java:595)

      

> this.persons = service.findAll();
If the not mistaken, the service.findAll() is returning null.
You need to return an empty array list.

No, this is struts2+spring+hibernate+jpa....
Service is spring part of app. You can find code on http://struts.apache.org/2.0.8/docs/struts-2-spring-2-jpa-ajax.html

I'm just trying to add another functionality to this example application with books, and to make small library app - to make select box on book edit and to fill it with person's names and to stick selection to the person that presently borrowed the book.

What I means is that it might because there's no record in database and the service.findAll() is returning null.
Try check whether the returning value is null.

    this.persons = service.findAll();
    if (this.persons == null) {
        log.error("Persons null");
   }

The <s:select> tag does not accept List property with null..

Here is the solution:
instead of <s:select...> tag in index.jsp I inserted this:
<s:div id="selectPersons" theme="ajax" href="personSelect.action" />
in struts.xml I defined new action:

<action name="personSelect" class="personAction" method="execute">
   <result>pages/selectPersons.jsp</result>
   <result name="input">pages/selectPersons.jsp</result>
</action>

of course I made new jsp file named selectPersons.jsp in pages folder:

<%@ taglib prefix="s" uri="/struts-tags"%>
<s:select label="Select owner" name="persons" headerKey="-1" headerValue="-- Please Select --" list="persons" listValue="firstName" listKey="id"  emptyOption="true" />

Now I have list of all persons in select box on index.jsp, but there are few more tasks that I need to perform:
1. how to put this select box as last form element before button. Now it is on the top, probably because of <div>
2. How to integrate this in object that is selected in form when edit book action is performed. I already created this link using jpa notification (javax.persistence...) Now it takes some time to figure how to integrate more jsp pages into one object (Book)

Anyway thanks for the effort...and any comment and/or clarification on this is welcome.

If this <s:div id="selectPersons" theme="ajax" href="personSelect.action" /> is working, means your original code should be working as well.
How do you access the page? through jsp or action?

well...original page doesn't work...if it did work, I wouldn't ask for solution. Initially I'm accessing index.jsp

You can't directly accessing the jsp page, you need to call the action to dispatch the jsp page.

Accessing from the action is to invoke the Struts Interceptor so that it can load the action context, mapping, execute the action and load the properties (e.g persons) to the value stack. The struts tag and OGNL will then be able to refer those values in the value stack.

Sorry, maybe I wasn't clear enough...initially I'm accessing index.jsp, and all actions are called from it. Of course I don't accessing selectPersons.jsp directly. I thought that it was clear from my posts here.

Ok, let's see some concrete code. No points for theory. Thx.