It seems to me that what ought to happen is that he needs to set "volatile" to true, and "match" to false. I don't use "For" yet since I'm still using tapestry 3.0.3, but I do use Base:For (albeit a bit older version which doesn't use the match parameter). In any event, it seems that setting that to true should result in the correct behavior: updating the objects in the order in which they are pulled from the iterator (like Foreach does). You wouldn't even have to store your objects in the session. You could store the # of objects in a hidden field at the top of the form and use the hidden field's listener method to restore the appropriately sized list which would then be used by For. Not that you have to use some care here since you have to guarantee that you have the same # of objects in page render and page rewind (this is what volatile=false + match=true solves). But in this case, that should be trivial. Give it a whirl and see what happens? I've done stuff like this frequently with Foreach and with base:For. Give it a whirl. :)
Robert Schulte Marcus wrote: > No, it would definitely not ;). But as long as he uses session-persistence > for his rsvpList it should work, right? > > >>I don't think that would be consistently unique beyond the >>objects life. >> >>On 1/27/06, Schulte Marcus <[EMAIL PROTECTED]> wrote: >> >>>Hm, interesting problem. Now, your objects are equal but >> >>they are not the >> >>>same. So, I guess, you could use a keyExpression parameter >> >>referring to >> >>>the >>>objects' hashcode. In standard vm's, Object.hashCode() >> >>returns different >> >>>values for different instances. >>> >>>so, I'd try: >>> >>><div jwcid="@For" source="ognl:rsvpList" value="ognl:currentRsvp" >>>keyExpression="hashCode"> >>> >>>would that workf for you? >>> >>>Marcus >>> >>> >>>>-----Original Message----- >>>>From: Chris Conrad [mailto:[EMAIL PROTECTED] >>>>Sent: Thursday, January 26, 2006 9:49 PM >>>>To: Tapestry users >>>>Subject: Re: Non-intuitive behavior from the For component >>>> >>>> >>>>I think the problem here (and this is also in regards to using the >>>>keyProvider parameter and equals method) is I'm dealing >> >>with a list >> >>>>of objects which are 100% legitimately equal to each other. And >>>>that's really what I want. I want the For component to >> >>take a list >> >>>>of equal objects to render the page and then, during the rewind, >>>>update that list of objects according to their index in the list. >>>>When I start I have no identifying information about the list of >>>>objects, all I know is that I need x number of them. >>>> >>>>To try and explain in a different way ... if you look at the Form >>>>section of the Quick Start guide you can see the standard >>>>pattern for >>>>having a user fill in a form to create a new object. In the Quick >>>>Start guide it's creating a new ProjectRelease. So, as in the >>>>example, in your pageBeginRender you instantiate a blank >>>>ProjectRelease and when the form is submitted, the fields of the >>>>ProjectRelease are updated according to the values in the form. I >>>>want to do the same thing but instead of creating a single >>>>ProjectRelease, I want to create a list of ProjectReleases. >>>> >>>>Does that help any? >>>> >>>>--Chris >>>> >>>>On Jan 26, 2006, at 12:36 PM, Jesse Kuhnert wrote: >>>> >>>> >>>>>Hmmm....But that only causes more confusion I'm afraid :( >>>>> >>>>>Ohhhhhh....I think what you are doing sort of sounds right, >>>> >>>>but you >>>> >>>>>still >>>>>can't expect the For component to be able to know the difference >>>>>between all >>>>>of your objects if the equals() method on them doesn't >>>> >>>>enforce some >>>> >>>>>sort of >>>>>uniqueness. >>>>> >>>>>Have you tried playing with the "match" parameter to For? I've >>>>>normally used >>>>>the "ListEdit" component for things like this in the past. Would >>>>>love to >>>>>hear if "match" or some of the other parameters solve >> >>your problem. >> >>>>>On 1/26/06, Chris Conrad <[EMAIL PROTECTED]> wrote: >>>>> >>>>>>Sorry to reply twice, but I thought some code snippets >> >>might make >> >>>>>>things clearer. Here is what I do in my pageBeginRender: >>>>>> >>>>>> rsvpList = new ArrayList<Rsvp>(numberAttending); >>>>>> >>>>>> for (int i = 0; i < numberAttending; i++) { >>>>>> Rsvp rsvp = new Rsvp(); >>>>>> rsvp.setId(i); >>>>>> rsvp.setAttending(true); >>>>>> >>>>>> rsvpList.add(i, rsvp); >>>>>> } >>>>>> >>>>>> setRsvpList(rsvpList); >>>>>> >>>>>>My listener method looks like: >>>>>> >>>>>> // Reset the ids to 0 >>>>>> List<Rsvp> rsvpList = getRsvpList(); >>>>>> for (Rsvp rsvp : rsvpList) { >>>>>> rsvp.setId(0); >>>>>> } >>>>>> >>>>>> getRsvpData().setRsvpList(rsvpList); >>>>>> >>>>>>And then in my HTML template I use it like this: >>>>>> >>>>>> <div jwcid="@For" source="ognl:rsvpList" >>>>>>value="ognl:currentRsvp"> >>>>>> <div jwcid="@Any" element="div" >>>>>>class="ognl:evenOdd.next"> >>>>>> <p class="floatLeft"> >>>>>> <label jwcid="@FieldLabel" >>>>>>field="component:guestName">Guest's Name</label> >>>>>> <input jwcid="guestName" size="30"/> >>>>>> </p> >>>>>> >>>>>> <p class="floatLeft"> >>>>>> <label jwcid="@FieldLabel" >>>>>>field="component:meal">Meal</label> >>>>>> <input jwcid="meal"/> >>>>>> </p> >>>>>> <br class="clear"/> >>>>>> </div> >>>>>> >>>>>>The bit that bothers me is that in my pageBeginRender I >>>> >>>>need to do >>>> >>>>>>this: >>>>>> rsvp.setId(i); >>>>>> >>>>>>and in my listener I need to do this: >>>>>> >>>>>> // Reset the ids to 0 >>>>>> List<Rsvp> rsvpList = getRsvpList(); >>>>>> for (Rsvp rsvp : rsvpList) { >>>>>> rsvp.setId(0); >>>>>> } >>>>>> >>>>>>I need to do that exclusively so that the For >> >>component can update >> >>>>>>the List correctly. >>>>>> >>>>>>Hopefully that makes things a little clearer. >>>>>> >>>>>>--Chris >>>>>> >>>>>>On Jan 26, 2006, at 11:58 AM, Jesse Kuhnert wrote: >>>>>> >>>>>> >>>>>>>Hmmm. . >>>>>>> >>>>>>>I do these sort of things a lot, esp. with hibernate. >> >>I've found >> >>>>>>>the For >>>>>>>component to incredibly useful, but maybe the >> >>identification of >> >>>>>>>objects part >>>>>>>could be made more clear? >>>>>>> >>>>>>>I think the PropertySelectionModel problem could be >> >>solved if you >> >>>>>>>used the >>>>>>>"BeanPropertySelectionModel" class found in >>>>>>>http://tacos.sourceforge.netinstead. It makes turning >> >>a list of >> >>>>>>>hibernate objects into the selection >>>>>>>model a one-line argument. >>>>>>> >>>>>>>Let me know if you try that and still find problems. >>>>>>> >>>>>>>On 1/26/06, Chris Conrad <[EMAIL PROTECTED]> wrote: >>>>>>> >>>>>>>>Hello everyone, >>>>>>>> >>>>>>>>I'm working a tiny little RSVP for a friend. While >> >>doing so I >> >>>>>>>>found, >>>>>>>>what seems to me at least, a very non-intuitive result >>>> >>>>from the For >>>> >>>>>>>>component. Basically the behavior I want is: >>>>>>>> >>>>>>>>1. The user navigates to the RSVP page and is provided a >>>> >>>>drop down >>>> >>>>>>>>box to select the number of people who will be attending >>>> >>>>the event. >>>> >>>>>>>>2. The user is given a list of text entry boxes (to enter the >>>>>>>>name of >>>>>>>>the guest) and drop downs (to select the meal the >> >>guest wants). >> >>>>>>>>1 was simple to accomplish though having to create a >>>>>>>>PropertySelectionModel is kinda a pain for something >> >>this simple. >> >>>>>>>>Where things got hairy is 2. Basically the code >> >>flow is: in the >> >>>>>>>>listener for the form submit in #1, I grab the >> >>number of guests >> >>>>>>>>attending and set that on the meal selection page. The meal >>>>>>>>selection page's pageBeginRender creates a List of x >> >>RSVP objects >> >>>>>>>>where x is the number of guests attending. Then the >>>> >>>>meal selection >>>> >>>>>>>>page uses a For component to loop through the List of RSVP >>>>>>>>objects so >>>>>>>>that, in the first pass everything is blank and then >>>> >>>>when the guest >>>> >>>>>>>>submits, those RSVP objects in the List get filled >> >>in with the >> >>>>>>>>details the guest entered. >>>>>>>> >>>>>>>>Now, what actually happened is the first RSVP object in >>>> >>>>the list is >>>> >>>>>>>>continually updated over and the others are never >> >>touched. When >> >>>>>>>>tracing through the For components code, it appears to >>>> >>>>be trying to >>>> >>>>>>>>match the serialized object saved in the form >> >>against the ones >> >>>>>>>>in the >>>>>>>>List to "intelligently" pick which one to update. But >>>> >>>>since all of >>>> >>>>>>>>the RSVP objects were the same to start with, and the >>>> >>>>For component >>>> >>>>>>>>doesn't update it's internal mapping after updating >> >>an object, it >> >>>>>>>>just ignored everything in the list after the first >> >>item. Or, I >> >>>>>>>>guess more accurately, it continually matched the first >>>> >>>>item in the >>>> >>>>>>>>List and so it just repeatedly updated that one RSVP >> >>object. To >> >>>>>>>>work >>>>>>>>around this, I needed to set the RSVP's id in the >>>>>>>>pageBeginRender to >>>>>>>>a different value for each RSVP object and then >> >>reset them back >> >>>>>>>>to 0 >>>>>>>>just before sending them to Hibernate to persist (if I >>>> >>>>don't reset >>>> >>>>>>>>them to 0, Hibernate things it's a detached object >> >>and ends up >> >>>>>>>>updating a row instead of adding a new row). >>>>>>>> >>>>>>>>This work around seems very much like a hack to me. Is >>>> >>>>there a way >>>> >>>>>>>>to make the For component do the right thing (i.e. >>>> >>>>actually iterate >>>> >>>>>>>>over the array when rewinding instead of assuming it >> >>knows what >> >>>>>>>>it's >>>>>>>>doing)? I did try playing with the match parameter and that >>>>>>>>completely breaks everything, none of the objects in >> >>the List get >> >>>>>>>>updated. It seems that my use case isn't so terribly strange >>>>>>>>that it >>>>>>>>would be this difficult to accomplish in Tapestry. >>>>>>>> >>>>>>>>Thanks, >>>>>>>>--Chris >>>>>>>> >>>>>>>> >>>> >>------------------------------------------------------------------- >> >>>>>>>>-- >>>>>>>>To unsubscribe, e-mail: tapestry-user- >>>>>>>>[EMAIL PROTECTED] >>>>>>>>For additional commands, e-mail: tapestry-user- >>>>>>>>[EMAIL PROTECTED] >>>>>>>> >>>>>>>> >>>>>> >>>>>> >>>>>> >>--------------------------------------------------------------------- >> >>>>>>To unsubscribe, e-mail: >>>> >>>>[EMAIL PROTECTED] >>>> >>>>>>For additional commands, e-mail: tapestry-user- >>>>>>[EMAIL PROTECTED] >>>>>> >>>>>> >>>> >>>> >>>> >>--------------------------------------------------------------------- >> >>>>To unsubscribe, e-mail: >> >>[EMAIL PROTECTED] >> >>>>For additional commands, e-mail: >> >>[EMAIL PROTECTED] >> >>> >>--------------------------------------------------------------------- >> >>>To unsubscribe, e-mail: [EMAIL PROTECTED] >>>For additional commands, e-mail: >> >>[EMAIL PROTECTED] >> >>> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
