Does AbstractReadOnlyModel accomplish what you're talking about? Scott
On Wed, Mar 4, 2009 at 4:50 AM, Johannes Schneider <maili...@cedarsoft.com> wrote: > Hi, > > the concept of IModel seems to be very obvious. It is simply some kind > of reference and offers a getter and a setter. > > When used with ordinary object, everything works fine. An IModel that > contains a String can easily be mapped to a TextField. > The text field calls "getObject" to show the initial value and sets the > changed string to the model using "setObject" on form commit. > > > Everything becomes a little more complicated when collections are > affected. The problem is, that it is not obvious what those collections > represent. > > 1) A collection might be read-only (e.g. the possible choices for a > selection). > 2) But it also might be necessary to add/remove single elements (e.g. > privileged users shown within a shuffle list). > 3) And sometimes the complete collection is changed (can't find an > example here). > > > IModel only supports the *third* method where the complete collection is > replaced. > (Don't forget that the reference to the collection changes which will > lead to several other problems.) > I strongly recommend the usage of a wrapping class for that case. > But this case is not very common. Maybe someone finds a good example - I > can't. > > > For the other two cases it does *not* make any sense to call > IModel#setObject. > > > Summary: Nearly in every case when the IModel contains a collection, the > "setObject" method does not make any sense and must not be called. > > > Conclusion: I think we should have created some sort of IModelProvider > (contains only the getObject method) and IModel (with both methods). > Components that just *read* values from the model, accept the read only > interface now. > > For special cases where a magic component adds/removes elements to a > collection, we need some sort of ICollectionModel that offers "add" and > "remove" methods (but no setter). > That interface - of course - will be based upon a collection *without* > wildcards... > > > > Regards, > > Johannes Schneider > > > > > > > > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org > For additional commands, e-mail: users-h...@wicket.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
