DataModel and DataModelSelection staying populated on select()

[daxxy]

I have the following class:

@Scope(ScopeType.CONVERSATION)
@Name("iosBreakdownList")
public class IosBreakdownList {
     
     @In(create=true)
     private EntityManager entityManager;
     
     @DataModel
     private List<Object[]> iosVersions;
     
     @DataModelSelection
     @Out(required=false)
     private Object[] selectedIosVersion;

     public List<Object[]> getIosVersions() {
          List<Object[]> resultList = entityManager.createQuery("select d.devOsVer, count(*) from Devices d " +
          "where d.devOsVer != 'Error' group by d.devOsVer").getResultList();
          iosVersions = resultList;
          return iosVersions;
     }

     public String select(){
          return "os_selected";
     }
     
     @Remove
     public void destroy(){
     }
}

The data is displayed in a datatable:

<rich:dataTable id="iosBreakdownList" var="_ios"
        value="#{iosBreakdownList.iosVersions}"
        rowClasses="rvgRowOne,rvgRowTwo">
        <rich:column width="500px">
          <f:facet name="header">
            <h:outputText value="#{messages['ond.label.devosver']}" />
          </f:facet>
          <s:link action="#{iosBreakdownList.select()}" value="#{_ios[0]}"></s:link>
        </rich:column>
        <rich:column width="100px">
          <f:facet name="header">
            <h:outputText value="Count" />
          </f:facet>
          <h:outputText value="#{_ios[1]}" />
        </rich:column>
      </rich:dataTable>

I am watching the flow of things in the debugger and I don't understand what I'm seeing.  I have breakpoints on getIosVersions and select.  When I render the page, getIosVersions is called several times.  On the 2nd and subsequent times of calling it, selectedIosVersion is populated.

When I click on the link on the link, I jump to the breakpoint in my select() and both iosVersions and selectedIosVersions are null.  The page simply rerenders at that point, which is OK for now.  Ultimately I want to redirect to a new view using the selectedIosVersion as the input parameter.

But first I have to make sure I can even access iosVersions and selectedIosVersion.

Why is getIosVersion getting called multiple times?
Why is selectedIosVersion getting set when I haven't selected anything yet?
How are these things not hanging on to their content by the time I call select?

TDR

[daxxy]

Oops that title should be NOT staying populated

[asookazian]

There is always a temporary conversation in Seam.  I'm assuming there is no LRC in this case (unless there is a <begin-conversation/> tag in pages.xml for this particular action.

Try adding @Begin(join=true) to getIosVersions() to see if that makes a difference in terms of the number of calls to that method.

This is incorrect:

@DataModel
     private List<Object[]> iosVersions;
     
     @DataModelSelection
     @Out(required=false)
     private Object[] selectedIosVersion;

     public List<Object[]> getIosVersions() {
          List<Object[]> resultList = entityManager.createQuery("select d.devOsVer, count(*) from Devices d " +
          "where d.devOsVer != 'Error' group by d.devOsVer").getResultList();
          iosVersions = resultList;
          return iosVersions;
     }

do this instead:

@DataModel
     private List<Object[]> iosVersions;
     
     @DataModelSelection
     @Out(required=false)
     private Object[] selectedIosVersion;

     public void getIosVersions() {
          iosVersions = entityManager.createQuery("select d.devOsVer, count(*) from Devices d " +
          "where d.devOsVer != 'Error' group by d.devOsVer").getResultList();
          
     }

Because @DataModel outjects a ListDataModel, there is no need for the getIosVersions() method to return an Object.

As a quick check, I tried the following code:

xhtml:

<rich:dataTable id="breakdownList" var="_platform"
              value="#{insertAppSite.startup()}">
              <rich:column>
                    <h:outputText value="#{_platform[0]}" />
              </rich:column>
              <rich:column>
                   <h:outputText value="#{_platform[1]}" />
              </rich:column>
          </rich:dataTable>

with the following component backing bean:

@Stateful
@Name("insertAppSite")
@Scope(ScopeType.CONVERSATION)
public class TestStartupInsertApplicationSite implements TestStartupInsertApplicationSiteLocal {

     @In
     private EntityManager entityManager;
     
     @Logger
     private Log log;
     
     @DataModel
     private List<Object[]> resultCount;
     
     //@Begin(join=true)
     public void startup(){
          
          resultCount = entityManager.createQuery("select e.modelNumber, count(*) from Equipment e group by e.modelNumber").getResultList();
          
          log.info("resultCount.size() = "+resultCount.size());
          
          
     }
     
     @End(beforeRedirect=true)
     public void end(){
          //no op
     }
     
     @Destroy @Remove
     public void destroy(){
          log.info("in "+this.getClass().getName()+".destroy()");
     }
}

And it hit the startup() method only once with or w/o the @Begin(join=true).  So I'm not exactly sure why your backing bean method is being executed multiple times per HTTP request/response cycle (this does happen with getter methods that are bound to the rendered JSF attribute).

Is the <rich:dataTable> in a loop somehow like nested inside a <a4j:repeat>?

[daxxy]

(Giving up on formatted text. Argh)

Thanks again for helping me Arbi.

When I do a simple listing, like you have, getIosVersions is only called once to get the list.

When I replace h:outputText with a link that will allow me to select one of the options in the list, it is called 31 times, seemingly once for each os version (select count distinct dev_os results in 31) and selectedOsVersion is populated, though with the same result each time.

In other words, when I have this:

    <h:outputText value="#{_ios[0]}" />

getIosVersions is called once. As soon as I replace it with this:


    <s:link action="#{iosBreakdownList.select()}" value="#
{_ios[0]}"/>


It gets called once for each distinct occurence of osVersion (31 times in this case).

[asookazian]

How are you starting the LRC if at all?

[daxxy]

Not starting it at all.

I decided to scrap my idea of using DataModelSelection, which was the ultimate goal here and now I simply pass the selection to the new view as a parameter.

<s:link view="/ONDDevResultPage" value="#{_ios[0]}" >
       <f:param name="osver" value="#{_ios[0]}"/>
</s:link>

Though that does not solve the question of why the query is running so many times.

[asookazian]

I've had issues with @DataModelSelection when the dataTable is sorted.

You can get the rowIndex of the dataTable and pass that via JBoss EL instead.

action="#{bean.foo(rowIndex)}"