This is one of the main reason that Igor made DataView. On 9/14/05, Johan Compagner <[EMAIL PROTECTED]> wrote: > Updating by index works fine as long as the List behind it never changes. > > So if you know 100% sure that over request the list will not change > (add/remove/order) > then you can use index just fine. > But if you have a list of 10. and Index 1 points to a user "Jim" at render > time. > Then User "Johan" is inserted at index 1 and user "Jim" is gone to index2. > > If now a update model comes in then the a textfield holding the name "Jim" > will be bound to a > ListModel with index 1. He will get the user at index 1 but that is > suddenly "Johan" > And you will override everything of Johan with Jim. So suddenly you have 2 > jims... > (Maybe in this example that would be better, having no Johan but 2 jims ;)) > > If you store the ID of the user instead of the Index then before you update > the model > the user is loaded with its id. So it will not go wrong. > > So the rule is pretty simple: > Can the list change over/between request yes or no. If yes then store id's > if no then you can use index. > > > > On 9/13/05, Jim McBeath <[EMAIL PROTECTED]> wrote: > > On Tue, Sep 13, 2005 at 09:07:56PM +0200, Eelco Hillenius wrote: > > > I think that is how ListItem started out many months ago. There have > > > been several been several shouting indecent words about that, and it > > > was 'fixed' to what it is now. I don't know, someone else (Johan?) > > > should defend that decission. > > > > I would be interested in hearing about the potential problems associated > > with updating the underlying List using the index. If this has all been > > discussed before, I expect I could learn something from that discussion. > > I would not want to implement my own fix to do this, then run into some > > subtle problem down the road that has already been discussed here. > > Can anyone point me to an old discussion about this, or post a summary? > > > > If ListItemModel will not update the underlying list, should it perhaps > > not allow it's value to be set? I'm curious to see an example of where > > the ability to set the local object in the ListItemModel is useful. > > If others, like me, assume that the ListItemModel is usable for updating > > the underlying List, it would be helpful to have ListItemModel.onSetObject > > throw an exception with a message telling the developer that he can't do > that > > and will need to come up with another approach. > > > > -- > > Jim > > > > > > ------------------------------------------------------- > > SF.Net email is sponsored by: > > Tame your development challenges with Apache's Geronimo App Server. > Download > > it for free - -and be entered to win a 42" plasma tv or your very own > > Sony(tm)PSP. Click here to play: > http://sourceforge.net/geronimo.php > > _______________________________________________ > > Wicket-user mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/wicket-user > > > >
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