But how do you know that the list is changed?
The model behind the listview can change at any time at anyplace..
If you are having that kind of models (mostly selects from a database
where also inserts and deletes can occur on)
then you have to implement youre own ListItemModel anyway (so that you
don't depend on index but can hold
you're own id (the db pk) in that model.
See listview:
protected IModel getListItemModel(final IModel listViewModel, final int
index)
But with changing models from the outside world. (so not done through
youre session) is tricky.
Because what row should be thrown away? Where should we add one row?
And if you are in a pageablelist then going to a next page would cause a
removeall anyway
So a visiblity flag on one component in one listitem (row) will be gone
if you go from page 1 to 2 and back..
I think if you want these kind of things. You have to have some greater
model (in the ListView itself)
where you hold the state of the listems for a specific id (db pk) so
that when you make a listitem
you are checking the ListViews special model for special data.
johan
Ralf Ebert wrote:
Hi,
I must admit I don't understand what is different to the current
approach. IMO we need a simple flag which prevents calling
populateItem on each request, rather than only on the first one
(assuming the list does not change).
well, as long as the list doesn't change everything is fine, indeed.
But actually list changes can occur, for example after editing/
deleting/inserting entries. There should be a way to express how
these changes should be handled. Lets see what can happen:
1) List item added -> Generate the components
2) List item removed -> Throw away components
3) List item has changed -> Throw away component and re-generate them
OR notify components of model changes
The application should be able to decide how these changes are to be
handled, especially for case 3.
Not sure what you mean. a) A map does not provide a sequence b) a
ListItem does already have a relationship to a model. How does your
approach differ from the current one?
The current default ListItemModel class uses the list indexes to get
the ListItem from the model list item. When keeping the components
using setOptimizedItemRemoval and an item is inserted before other
entries, chaos occurs. This will not work for a component which
allows model upgrades without throwing away the existing components.
Regards,
Ralf
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