Yes, that's correct, when I use this approach, the collection displays the
correct content in the form listener. But:
When I do this, the collection is serialized, causing a long Base64 encoded
string. I don't want that, becaus it may cause my html to become very large
and too big to submit.
I might be able to solve this by creating my own datasqueezer for
collections.
Anyway, thanks a lot, I see now why my collections are never auto-populated!
Inge
On 2/17/06, Todd O'Bryan <[EMAIL PROTECTED]> wrote:
>
> As long as your collection is Serializable, you don't need a custom
> DataSqueezer. The problem is that Tapestry isn't saving the
> information about the collection itself. This is the problem I was
> having with my String[].
>
> Add a hidden field above your @For to save the items info:
>
> <input type="hidden" jwcid="@Hidden" value="ognl:items" /> <!-- I
> don't think "ognl:" is necessary in 4.0, but I'm still using 3-->
>
> and getItems() will not return null in the listener.
>
> Todd
>
>
> On Feb 17, 2006, at 4:52 AM, Inge Solvoll wrote:
>
> > Does there exist an example (vlib or similar) of a page that only gets
> > information from database on render, and that uses a custom
> > datasqueezer and
> > no db fetching for the rewind phase? My ideal design is that all known
> > information in the rewind phase comes from request parameters, that
> > way many
> > synchronization issues can be avoided (request not matching content
> > from
> > database or other state).
> >
> > Inge
> >
> > On 2/16/06, Inge Solvoll <[EMAIL PROTECTED]> wrote:
> >>
> >> 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
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>> --------------------------------------------------------------------
> >>> -
> >>>>> To unsubscribe, e-mail: tapestry-user-
> >>>>> [EMAIL PROTECTED]
> >>>>> For additional commands, e-mail:
> >>> [EMAIL PROTECTED]
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>
> >>> --------------------------------------------------------------------
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> >>> For additional commands, e-mail: tapestry-user-
> >>> [EMAIL PROTECTED]
> >>>
> >>>
> >>
>
>
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