I'm working on a Web application which uses Spring and Hibernate frameworks. Right now I would like to remove the Serializable interface implementation from my Viaggio.java class, a JPA Entity. Entities of this class are displayed inside my Wicket page through a PageableListView. When I render the web page I get a NotSerializableException. Here's a snippet of the code that instantiate the ListView:
final LoadableDetachableModel<List<Viaggio>> viaggiListModel = new LoadableDetachableModel<List<Viaggio>>() {
@Override
protected List<Viaggio> load() {
List<Viaggio> viaggi = utenteService.findAllViaggiForDataAndUsername(dataSelected, utente);
return viaggi;
}
};
final WebMarkupContainer container = new WebMarkupContainer("tableResult");
container.setOutputMarkupId(true);
PageableListView repeating = new PageableListView("repeating", viaggiListModel, 10) {
@Override
protected void populateItem(ListItem item) {
final Viaggio viaggio = (Viaggio) item.getModelObject();
String date = new SimpleDateFormat("dd-MM-yyyy").format(viaggio.getData());
item.add(new Label("data", date));
item.add(new Label("automezzo", new PropertyModel(viaggio, "targaMotrice")));
item.add(new Label("autista", new PropertyModel(viaggio, "primoAutista")));
item.add(new EnumLabel("status", new PropertyModel(viaggio, "status")));
......
I append down here the stacktrace printed:
24/02/2018 09:06:22,629 ERROR -JavaSerializer - Error serializing object class it.loginet.buonicarico.presentation.ViaggioListPage [object=[Page class = it.loginet.buonicarico.presentation.ViaggioListPage, id = 2, render count = 1]]
org.apache.wicket.core.util.objects.checker.CheckingObjectOutputStream$ObjectCheckException: The object type is not Serializable!
A problem occurred while checking object with type: it.loginet.buonicarico.domain.utente.Viaggio
Field hierarchy is:
2 [class=it.loginet.buonicarico.presentation.ViaggioListPage, path=2]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
private java.lang.Object org.apache.wicket.MarkupContainer.children[5] [class=org.apache.wicket.markup.html.WebMarkupContainer, path=2:tableResult]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
private java.lang.Object org.apache.wicket.MarkupContainer.children[0] [class=org.apache.wicket.markup.html.navigation.paging.PagingNavigator, path=2:tableResult:navigator]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
private java.lang.Object org.apache.wicket.MarkupContainer.children[0] [class=org.apache.wicket.markup.html.navigation.paging.PagingNavigation, path=2:tableResult:navigator:navigation]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=org.apache.wicket.markup.html.list.LoopItem, path=2:tableResult:navigator:navigation:0]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=org.apache.wicket.markup.html.navigation.paging.PagingNavigationLink, path=2:tableResult:navigator:navigation:0:pageLink]
protected final org.apache.wicket.markup.html.navigation.paging.IPageable org.apache.wicket.markup.html.navigation.paging.PagingNavigationLink.pageable [class=org.apache.wicket.markup.html.list.PageableListView, path=2:tableResult:repeating]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=org.apache.wicket.markup.html.list.ListItem, path=2:tableResult:repeating:0]
private java.lang.Object org.apache.wicket.MarkupContainer.children [class=[Ljava.lang.Object;]
java.lang.Object org.apache.wicket.Component.data[1] [class=org.apache.wicket.markup.html.basic.Label, path=2:tableResult:repeating:0:automezzo]
java.lang.Object org.apache.wicket.Component.data [class=org.apache.wicket.model.PropertyModel]
private java.lang.Object org.apache.wicket.model.ChainingModel.target [class=it.loginet.buonicarico.domain.utente.Viaggio] <----- field that is causing the problem
at org.apache.wicket.core.util.objects.checker.CheckingObjectOutputStream.internalCheck(CheckingObjectOutputStream.java:362)
at org.apache.wicket.core.util.objects.checker.CheckingObjectOutputStream.check(CheckingObjectOutputStream.java:341)
It clearly states my Viaggio field inside PropertyModel is not serializable, it finally points the finger to the "automezzo" Label i'm adding to the ListItem.
Where am I missing the point? LoadableDetachableModel that wraps my list of Viaggio entities seems to be used correctly.
All your labels reference PropertyModels, which themselves directly reference your entity.
As a rule of thumb you should never call IModel#getObject() and keep its result around longer than needed:
final WebMarkupContainer container = new WebMarkupContainer("tableResult");
container.setOutputMarkupId(true);
PageableListView<Viaggio> repeating = new PageableListView<Viaggio>("repeating", viaggiListModel, 10) {
@Override
protected void populateItem(ListItem<Viaggio> item) {
final IModel<Viaggio> viaggio = item.getModel();
item.add(new Label("data", new AbstractReadOnlyModel<String>() {
public String getObject() {
return new SimpleDateFormat("dd-MM-yyyy").format(viaggio.getObject().getData())
}
});
item.add(new Label("automezzo", new PropertyModel(viaggio, "targaMotrice")));
item.add(new Label("autista", new PropertyModel(viaggio, "primoAutista")));
item.add(new EnumLabel("status", new PropertyModel(viaggio, "status")));
......
Instead of the AbstractReadOnlyModel you could use a PropertyModel too, and let a Converter do the formatting of the date.