def on_selection_changed(self, selection):
model, iter = selection.get_selected()
if iter is not None:
self.selected_path = model.get_path(iter)
self.selected_book = Book.fetch(model[iter][self.ISBN],
model[iter][self.TITLE],
model[iter][self.AUTHOR],
self.parent.db)
self.parent.set_active_book(self.selected_book)
else:
self.selection = None
self.selected_book = None
