Wicket ListView not refreshing

问题:

I am taking my first steps with Apache Wicket and ran into the following problem. I have a ListView that displays a "delete" link right next to its entries. When the delete link is clicked, the entity represented by the list item is deleted from the database but the list itself does not get updated until I reload the page manually in the browser.

IModel<List<SampleEntity>> sampleEntityListModel = new LoadableDetachableModel<List<SampleEntity>>() {
        @Override
        protected List<SampleEntity> load() {
            return mSampleEntityBA.findAll();
        }
    };

mListview = new ListView<SampleEntity>("listview", sampleEntityListModel) {
        @Override
        protected void populateItem(final ListItem<SampleEntity> item) {
            item.add(new Label("listlabel", new PropertyModel<String>(item.getModelObject(),
                    "text")));
            item.add(new Link<SampleEntity>("deleteLink", item.getModel()) {
                @Override
                public void onClick() {
                    mSampleEntityBA.delete(item.getModelObject());
                }
            });
        }
};

回答1:

When onClick called, item.getModelObject() pulls from the sampleEntityListModel which in turn calls mSampleEntityBA.findAll(). The model object of sampleEntityListModel will be cached for the duration on the request cycle (until it is detached - which is usually what you want) and is not aware of the call to delete().

In order to refresh the sampleEntityListModel, add a sampleEntityListModel.detach() call just after the delete (sampleEntityListModel must be made final, but this will not cause any extra state to be serialized). This will cause the model to fetch a fresh set of data when the list view is rendered later in the request cycle.

回答2:

You probably want an AjaxLink instead of that Link, and then you have to make the list refresh, using the tactics described here, possibly adjusting a bit for the fact that the wiki has Wicket 1.3 code instead of 1.4.

But you might also be better off with a different repeater, such as a RefreshingView or a DataView. There are some examples of assorted repeaters here. While none of them are exactly what you're looking for, looking at that code might help.

回答3:

looks like the problem is that your mSampleEntityBA.findAll(); is returning incorrect data. hard to help without seeing more code.

on a different note, you should really be using DataView when working with database-backed lists.

回答4:

You might also want to check out JQGrid from the wiQuery project instead of DataView.