It appears your problem is that getItems() will always be null in
pageBeginRender because at that point parameters have not been bound.
Try removing that else clause.
Ryan
On 2/16/06, Inge Solvoll <[EMAIL PROTECTED]> wrote:
> I guess my (first) problem is simpler than this discussion, I'll try to
> explain:
>
> When I submit my form, I expect my page properties to be updated during
> rewind automatically, without me having to write any java code to make that
> happen. But so far I haven't understood how this happens. I include here a
> simple code example that I think illustrates my problem quite well. Why is
> my collection always empty when the form listener is reached? If I run the
> initItems() method on both rewind and render, the values from the request
> parameters are written into the page properties.
>
> My ultimate question is: Do I really have to get the items list from the
> database during rewind? Isn't there a way to avoid this, making tapestry
> automatically build the items collection from the request parameters? As I
> wrote in another similar post on the list about DataSqueezer, I've tried
> creating a datasqueezer for this, but the collection is still showing up
> empty.
>
> My HTML file:
>
> --------------------------------------------------------------------------
>
> <body jwcid="@Body">
>
> <form jwcid="@Form" listener="listener:formListener">
>
> <span jwcid="@For" source="ognl:items" value="ognl:currentItem">
> <span jwcid="@Insert" value="ognl:currentItem.name"/><br>
> <input type="text" jwcid="@TextField" value="ognl:currentItem.name"/>
> <br>
> </span>
>
> <input type="button" jwcid="@Submit" value="Submit form now"/>
>
> </form>
> </body>
>
> -------------------------------------------------------------
>
> <page-specification class="Test">
> <property name="items"/>
> <property name="currentItem"/>
> </page-specification>
>
> -------------------------------------------------------------
>
>
> public abstract class Test extends BasePage implements
> PageBeginRenderListener {
>
> static Log log = LogFactory.getLog(Test.class);
>
> public abstract Collection getItems();
> public abstract void setItems(Collection c);
>
> public void pageBeginRender(PageEvent event) {
>
> if (!getRequestCycle().isRewinding()) {
> initItems();
> }
> else {
> if (getItems() == null) {
> setItems(new Vector());
> }
> }
> }
>
> public void formListener(IRequestCycle cycle) {
> Collection items = getItems();
> for (Iterator iter = items.iterator(); iter.hasNext();) {
> Item currItem = (Item) iter.next();
> log.debug("Current item id: " + currItem.getId() + ", name: " +
> currItem.getName());
> }
> }
>
> private void initItems() {
> Collection items = new Vector();
>
> items.add(new Item(new Long(1), "Item 1"));
> items.add(new Item(new Long(2), "Item 2"));
>
> setItems(items);
> }
> }
>
>
>
>
>
>
>
> On 2/15/06, Ryan <[EMAIL PROTECTED]> wrote:
> >
> > You may want to look at the method prepareForRender(). This is the
> > method that handles binding of properties to form values. It is also
> > called just before the component is rendered and in the order in which
> > they are rendered on the page (where pageBeginRender is called before
> > anything renders and is called in an undefined order). Also note that
> > prepareForRender is not called if the component is not rendered (for
> > instance if it is in an @Conditional that evaluates to false).
> >
> > I have received the best results from using pageBeginRender for
> > initializing page properties that are static (ie known at all times
> > during render, for instance a property select model property) and
> > using prepareForRender in other times.
> >
> > Ryan
> >
> > On 2/14/06, Inge Solvoll <[EMAIL PROTECTED]> wrote:
> > > I would like to provoke some debate on whether this is a good design
> > pattern
> > > or not:
> > >
> > > public void pageBeginRender(PageEvent event) {
> > > initState();
> > > readItemsFromDatabase();
> > > }
> > >
> > > private Collection readItemsFromDatabase() {
> > > return getDatabaseConnection().getItems();
> > > }
> > >
> > > private void initState() {
> > > // Init all crucial page state here
> > > }
> > >
> > > My problem is that some ids in hidden inputs are needed by the initState
> > > method. These values are not available in the pageBeginRender method
> > during
> > > rewind, because the Hidden components containing them haven't been
> > rendered
> > > yet. I need this state information on a per-request basis, not
> > per-session,
> > > so it is not possible to persist the page property. So far, I'm solving
> > this
> > > by using good-old request parameters, and reading them the old servlet
> > way
> > > in the pageBeginRender method like this:
> > >
> > > String crucialId = getRequest().getParameter("crucialId");
> > > page.setCrucialId(new Long(crucialId));
> > >
> > > I generally run into a lot of problems trying to find a good pattern for
> > > setting up data to fit with the RequestCycle. I have ended up doing the
> > > database reading in the pageBeginRender method, meaning that my data for
> > the
> > > page is being read on every single rewind and render. I find it a bit
> > hard
> > > to understand how to achieve this:
> > >
> > > On render:
> > > - Read data from database and set page properties
> > >
> > > On rewind:
> > > - Create non-null, empty, page properties ready to be populated from the
> > > request.
> > >
> > > My rewind step here often fails, and I don't see why. My page properties
> > > don't seem to be populated, when I leave them as, say, a non-null empty
> > > java.util.Collection to be populated with items from the request.
> > >
> > > Long and not very concentrated post, I actually don't know where to
> > start
> > > here :)
> > >
> > > Inge
> > >
> > >
> >
> > ---------------------------------------------------------------------
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> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
> >
>
>
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