[jbossseam-issues] [JBoss JIRA] Commented: (JBSEAM-2469) add postback flag to page actions

[Stephen Friedrich (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBSEAM-2469?page=comments#action_12414169 ] 
            
Stephen Friedrich commented on JBSEAM-2469:
-------------------------------------------

Hm, many of my pages are reachable both through get (search results links) and through postbacks (navigating through a hierarchy).
I need to to implement both ways:
The first for bookmarkable links (or links from other places at our intranet to specific products in my catalog app), the latter for usability and performance (using ajax to update only relevant parts when for example a dropdown value is changed).

It seems to me that what this request really aims at, is to have the page action triggered only once for the page.
Rather than having a special "postback" flag, could we have a mechanism instead that automatically sets a flag in page context to indicate that the page action already has been executed once, and check that if the option is true at the page action?


> add postback flag to page actions
> ---------------------------------
>
>                 Key: JBSEAM-2469
>                 URL: http://jira.jboss.com/jira/browse/JBSEAM-2469
>             Project: Seam
>          Issue Type: Feature Request
>          Components: Core
>    Affects Versions: 2.0.1.CR1
>            Reporter: Dan Allen
>         Assigned To: Dan Allen
>             Fix For: 2.1.0.BETA2
>
>   Original Estimate: 1 hour
>  Remaining Estimate: 1 hour
>
> Page actions are incredibly useful, but sometimes they can get in the way during a postback. I would like to see a postback attribute added to the <action> tag that can be used to disable the action on postback. It's possible using a conditional, but it is ugly and a lot of typing.
> Here is the logic that would go into Pages.java
>     private boolean isPostBack(FacesContext facesContext)
>     {
>         return facesContext.getExternalContext().getRequestParameterMap().
>               containsKey(ResponseStateManager.VIEW_STATE_PARAM);
>     }
> The conditional alternative would be:
> <action execute="#{component.action}" if="#{empty param['javax.faces.ViewState']}"/>

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