Page params + action doubt.

[fmontezuma]

I have a page with a parameter in the URL and I want to load data based on it, but I have to convert/validate this parameter, so I used page params to do it.

If I use a page action to load the data and use pagination the page action is called everytime I click to move to another page. Anyway to change this? I want to load data only once during the conversation scope.

I tried to use @Create, but this method is called before the page params are inserted in the bean. The same doesn't happen when I use @RequestParameter.

Thanks.

[fmontezuma]

I read in Seam in Action (page 125) that to ensure that a page action get executed only during an initial request I should use the conditional:

<action execute="#{actionBean.executeOnInitialRequestOnly}" 
   if="#{empty param['javax.faces.ViewState']}"/>

It have a footnote saying that in JSF 1.2, this check is performed by the ResponseStateManager isPostback(FacesContext) method.

I didn't understand what he mean with this.

[germanescobar]

You need to define the actionBean.executeOnInitialRequestOnly() method somewhere like this:

@Name("actionBean")
public class ActionBean {

  public boolean executeOnInitialRequestOnly() {
    ResponseStateManager rtm = FacesContext.getCurrentInstance().
        getRenderKit().getResponseStateManager();
    return rtm.isPostback(FacesContext.getCurrentInstance());
  }
     
}

This way you ensure that your page action method will be called only once when the page is loaded for the first time and not on postback.

Hope it helps!

[mwohlf]

not sure if I miss something here, but I wonder why you don't use on-postback="false" like so:

  <action execute="#{actionBean.executeSomeMethod}" on-postback="false" />