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
