Wicket SortableDataProvider - how to sort? - sorting

Question

I've got this webpage using Wicket, which loads in some data with some headlines, and then tons of rows beneath with the corresponding data.
Now, I want my data to be able to get sorted when i click on one of the headlines. From what I've found on google, SortableDataProvider is the way to go. But every example I find requires 1 parameter, whereas when I implement it, it requires two. What to do?
My class to sort is this:
public class SimpleDataView extends WebPage {
public SimpleDataView() {
addNumberOfRecords();
addHeadlines();
addRecords();
}
private void addNumberOfRecords() {
Data dataModel = getDataModel().getObject();
add(new Label("size", "Number of records: " + dataModel.numberOfRecords()));
}
private void addRecords() {
Data dataModel = getDataModel().getObject();
ListView records = new ListView("records", dataModel.getRecords()) {
#Override
protected void populateItem(ListItem item) {
item.add(new ListView("recordColumn", item.getModel()) {
#Override
protected void populateItem(ListItem item) {
item.add(new Label("value", item.getModel()));
}
});
}
};
add(records);
}
private void addHeadlines() {
Data dataModel = getDataModel().getObject();
ListView headlines = new ListView("headlines", dataModel.getHeaders()) {
#Override
protected void populateItem(ListItem item) {
item.add(new Label("headlineColumn", item.getModel()));
}
};
add(headlines);
}
private IModel<Data> getDataModel() {
IModel<Data> model = new LoadableDetachableModel<Data>() {
#Override
protected Data load() {
DataHandler dataHandler = new DataHandlerImpl();
return dataHandler.getDataFromSource();
}
};
return model;
}
}

Answer 1

This is a basic example in the Wicket wiki.
https://cwiki.apache.org/confluence/display/WICKET/Simple+Sortable+DataTable+Example
You can adjust the columns if you need more or less columns.

Answer 2

If you use SortableDataProvider, you should (when creating columns) define a sortProperty in the column's creation. Every one of the sortable-filterable columns has a constructor, with the possibility to define by hand the sortProperty.
It should by the way be identical to the generated SQL query's part that it points to.