When to set a source for a foreach component to null?

[freaquac <jo...@freaquac.de>]

Hi all,
a simple question with hopefully a simple anwser, but I haven't found it yet:

I have two pages. The first page maintains a set of Items stored in an 
ArrayList. The second page should display the Items in a form and give the 
possibility of feedback. The difficulty is that the ArrayList of Items should 
be cleared as soon as they are displayed by page 2.

To avoid a stale page the best place to do so would possibly be in the forms 
listener method on page2. But that wouldn't cover the "evil" browser back 
button. The user can navigate back and the ArrayList is not deleted/cleared.

Another possibility is to delete the ArrayList shortly after calling page2 
from page1 (listed beneath). But that gets me a get a stale page. 

//in page 1
public void viewItems(IRequestCycle cycle){
	  	ViewItems page2 = (ViewItems )cycle.getPage("ViewItems");
	  	view.viewItems(cycle,(ArrayList)getUser().getItems());
	 	
		getUser().setItems(null);
	  	return;
 }


As far as I understand the ListEdit component it wouldn't change anything if I 
use it. Cause in the synchronize method of the ListEdit component I would 
always get null values back because my source ArrayList is deleted and I 
couldn't synchronize the keys against values.

The only doable possibility I see in the moment is to add a delete flag to the 
Item class and set it as soon as it is displayed as part of the ArrayList. 
Then I can check at page1 if there is something to delete from before calling 
page2 the next time.

As I'm new to tapestry and not sure if I have already grasped the ways behind 
it ;-), I would love to have some input from you about this problem. Maybe I 
have overseen the obvious.

Greetings,
 Markus 


---------------------------------------------------------------------
To unsubscribe, e-mail: tapestry-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: tapestry-user-help@jakarta.apache.org

Re: When to set a source for a foreach component to null?

[John Studarus <st...@jhlconsulting.com>]

  Let me get this straight...

  Page 1 lists the items and Page 2 edits an item?
Let's call Page 1 ListItems and Page 2 EditItem.
You'll want something like:

  ListItems:

    public abstract Item getItem() ;  // this is set in the foreach

    // this is called from an actionlink
    public void viewItems(IRequestCycle cycle){
      EditItemPage next_page = (EditItemPage)cycle.getPage("EditItem");
      next_page.setItem(cycle, getItem()) ;  // or if you are using Hibernate set the Item Id/Key
      cycle.activate(next_page) ;
      return;
    }

  EditItem:

    <property-specification name="item" type="Item" persistent="yes"/>

    // this item will be reset automatically by Tapestry when sent back to the pool for reuse
    public abstract Item setItem(Item item) ;  // persistent object from page file


  Does that make sense?  Did I understand your problem correctly?

        John

  



On Sun, Apr 04, 2004 at 10:16:49PM +0200, freaquac wrote:
> Hi all,
> a simple question with hopefully a simple anwser, but I haven't found it yet:
> 
> I have two pages. The first page maintains a set of Items stored in an 
> ArrayList. The second page should display the Items in a form and give the 
> possibility of feedback. The difficulty is that the ArrayList of Items should 
> be cleared as soon as they are displayed by page 2.
> 
> To avoid a stale page the best place to do so would possibly be in the forms 
> listener method on page2. But that wouldn't cover the "evil" browser back 
> button. The user can navigate back and the ArrayList is not deleted/cleared.
> 
> Another possibility is to delete the ArrayList shortly after calling page2 
> from page1 (listed beneath). But that gets me a get a stale page. 
> 
> //in page 1
> public void viewItems(IRequestCycle cycle){
> 	  	ViewItems page2 = (ViewItems )cycle.getPage("ViewItems");
> 	  	view.viewItems(cycle,(ArrayList)getUser().getItems());
> 	 	
> 		getUser().setItems(null);
> 	  	return;
>  }
> 
> 
> As far as I understand the ListEdit component it wouldn't change anything if I 
> use it. Cause in the synchronize method of the ListEdit component I would 
> always get null values back because my source ArrayList is deleted and I 
> couldn't synchronize the keys against values.
> 
> The only doable possibility I see in the moment is to add a delete flag to the 
> Item class and set it as soon as it is displayed as part of the ArrayList. 
> Then I can check at page1 if there is something to delete from before calling 
> page2 the next time.
> 
> As I'm new to tapestry and not sure if I have already grasped the ways behind 
> it ;-), I would love to have some input from you about this problem. Maybe I 
> have overseen the obvious.
> 
> Greetings,
>  Markus 
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: tapestry-user-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: tapestry-user-help@jakarta.apache.org

---------------------------------------------------------------------
To unsubscribe, e-mail: tapestry-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: tapestry-user-help@jakarta.apache.org