[jbossseam-issues] [JBoss JIRA] Commented: (JBSEAM-2748) s:link and s:button with a view parameter are preloading the view

[Peter Boevink (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBSEAM-2748?page=comments#action_12403578 ] 
            
Peter Boevink commented on JBSEAM-2748:
---------------------------------------

Workaround:

A workaround is available by adding all parameters present in UserEdit.page.xml to the <s:link> tag e.g.:
<s:link view="UserEdit.xhtml">
     <f:param name="userId"/>
     <s:conversationPropagation type="nested" /> 
</s:link> 

If UserEdit.xhtml however contained a lot of collections/lists (seperated in tab panels), you might end up with a lot of params that are not relevant.
<s:link view="UserEdit.xhtml">
     <f:param name="userId"/>
     <f:param name="friendsOrder"/>
     <f:param name="friendsFirstResult"/>
     <f:param name="hobbyOrder"/>
     <f:param name="hobbyFirstResult"/>
     <s:conversationPropagation type="nested" /> 
</s:link> 


IMHO a fix should concentrate on the following seam stuff:
org.jboss.seam.ui.component.UISeamCommandBase.getUrl()
    ===
           if (viewId != null)
           {
                Map<String, Object> pageParameters = Pages.instance().getStringValuesFromModel(context, viewId, usedParameters);
    ===

org.jboss.seam.navigation.Pages.getStringValuesFromModel(..., ..., ...)
    ===
               else
               {
                  value = pageParameter.getStringValueFromModel(facesContext);
               }
    ===

org.jboss.seam.navigation.Param.getStringValueFromModel(...)
      Object value = getValueExpression().getValue();

org.jboss.seam.core.Expressions.getValue()
         {
            return (T) toUnifiedValueExpression().getValue( getELContext() );
         } 

org.jboss.seam.el.EL.createELResolver()
    ===
          new SeamELResolver()
    ===

org.jboss.seam.el.SeamELResolver.getValue(..., ..., ...)
    ===
      if (base==null)
      {
         return resolveBase(context, property);
      }
    ===

org.jboss.seam.el.SeamELResolver.resolveBase(..., ...)
    ===
      Object result = init.getRootNamespace().getComponentInstance(key);
    ===

org.jboss.seam.Namespace.getComponentInstance(String key)
   {
      return getComponentInstance(key, true);
   }


org.jboss.seam.Namespace.getComponentInstance(String key, boolean create)
   {
      return Component.getInstance( qualifyName(key), create );
   }


where the boolean 'create'  parameter causes the SeamObject to be created if it does not exist yet.


> s:link and s:button with a view parameter are preloading the view
> -----------------------------------------------------------------
>
>                 Key: JBSEAM-2748
>                 URL: http://jira.jboss.com/jira/browse/JBSEAM-2748
>             Project: JBoss Seam
>          Issue Type: Bug
>          Components: JSF Controls
>    Affects Versions: 2.1.0.A1
>         Environment: WinXP, jboss-4.2.2.GA, JDK1.5.*, jboss-seam-2.1.0.A1
>            Reporter: Peter Boevink
>
> Create a JSF view (e.g. UserList.xhtml) which makes use of  <s:link/> or <s:button/> including the 'view' parameter e.g.:
> <s:link view="UserEdit.xhtml"/>
> UserList.seam should be rendered making use of a long-running conversation,  e.g.:
> UserList.page.xml:
> <begin-conversation/>
> The 'UserEdit.page.xml' references a bean by making use of:
> <action execute="#{userHome.wire}"/>
> Now visit the UserList.seam page which holds the s:link reference to UserEdit.xhtml.....
> Don't click this s:link but open the debug.seam page to see what conversations exist with their objects.
> You''ll see a long running conversation (created by UserList.page.xml).
> Surprisingly, this conversation contains a 'userHome' object that should not be created before loading UserEdit.seam!
> Expected behaviour is than a long running conversation without objects.
> Making use of the <s:link/> tag with a typo in the 'view' parameter:
> <s:link view="typo.xhtml"/>
> Creates a long-running conversation without objects.
> So it looks like the page referred by the view parameter is somehow rendered and the beans referred by that page are pre-loaded in the currently active conversation scope.
> This causes undesired behaviour when making use of nested conversation e.g.:
> <s:link view="UserEdit.xhtml" propagation="nest"/>
> or
> <s:link view="UserEdit.xhtml">
>      <s:conversationPropagation type="nested" />
> </s:link>
> The beans referred by the UserEdit.seam page are now loaded in the parent conversation instead of the nested one.

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