Yes, items is always null in pageBeginRender. If I remove the else clause,
it is also null in the form listener. The else clause just prevents null
values before render.
I actually expect the values to be null in pageBeginRender, but I expect the
collection to be populated in the end of the rewind, in the form listener...
Inge
On 2/16/06, Ryan <[EMAIL PROTECTED]> wrote:
>
> 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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