Strange Spring #SessionAttributes Behavior - spring

Question

I'm using #SessionAttributes on 2 controllers and am experiencing some very strange behavior. My first controller (ViewController) is simply a view controller that displays JSP pages. The other is a controller that handles Ajax requests (AjaxController). I have a session attribute that is simply an object that has a HashMap as a member. The object is a wrapper around the map. The map is populated from the database and put in the session, which displays fine via the ViewController. However, when I do a delete from the map via an ajax request (AjaxController) and refresh the page, ViewController SOMETIMES shows that the element is removed, yet other times the element is still there. Here's code snippets:
ViewController (the homepage simply displays the contents of the map contained by userSettings
#Controller
#SessionAttributes({"userSettings"})
public class ViewController {
#RequestMapping(value="/", method=RequestMethod.GET)
public String home(ModelMap model) {
UserSettings userSettings = (UserSettings) model.get("userSettings");
String userListenersJson = userSettings.toJson(); // for bootsrtapping the js on the front end
return "views/home";
}
}
AjaxController:
#Controller
#SessionAttributes({"userSettings"})
public class AjaxController {
#RequestMapping(value="/users/listeners/{externalId}", method=RequestMethod.DELETE)
public #ResponseBody
AjaxResponse<?> deleteListener(ModelMap model,
#PathVariable long externalId) {
UserSettings userSettings = (UserSettings) model.get("userSettings");
userSettings.removeSetting(externalId);
return new AjaxResponse<String>(null, true);
}
}
Am I using #SessionAttributes wrong here? Why would this work sometimes and not others? I've also tried putting all of the view and ajax functionality in the same controller and experienced the same behavior.
Thanks for any help!
EDIT:
I've refactored my code a bit to use the UserPrincipal via springsecurity. My understanding is that this object is stored in the session. Regardless, I'm seeing exactly the same behavior.
Here's the UserPrincipal constructor that populates the user settings map. I've set breakpoints here to ensure that the correct listenerDBOs are set - they are, every time. This is the only time the listeners get set from the db into the UserSettings object in CustomUserPrincipal. All other adds/removes are done via the controllers (quick aside: adds never fail... only removes):
public CustomUserPrincipal(UserDBO userDBO) {
// set UserSettings obj
UserSettingsAdapter.addListeners(userDBO.getUserListenerDBOs(), userSettings);
}
The UserSettings object itself:
public class UserSettings implements Serializable {
private static final long serialVersionUID = -1882864351438544088L;
private static final Logger log = Logger.getLogger(UserSettings.class);
private Map<Long, Listener> userListeners = Collections.synchronizedMap(new HashMap<Long, Listener>(1));
// get the listeners as an arraylist
public List<Listener> userListeners() {
return new ArrayList<Listener>(userListeners.values());
}
public Map<Long, Listener> getUserListeners() {
return userListeners;
}
public Listener addListener(Listener listener) {
userListeners.put(listener.getId(), listener);
return listener;
}
// I'm logging here to try and debug the issue. I do see the success
// message each time this function is called
public Listener removeListener(Long id) {
Listener l = userListeners.remove(id);
if (l == null) {
log.info("failed to remove listener with id " + id);
} else {
log.info("successfully removed listener with id " + id);
}
log.info("Resulting map: " + userListeners.toString());
log.info("Map hashcode: " + userListeners.hashCode());
return l;
}
public Listener getListener(long id) {
return userListeners.get(id);
}
}
This is the helper function in the UserSettingsAdapter class that adds to the UserSettings object, called from CustomUserDetails constructor:
public static void addListeners(Set<UserListenerDBO> userListeners, UserSettings userSettings) {
for (UserListenerDBO userListenerDBO : userListeners) {
if (userListenerDBO.isActive()) {
addListener(userListenerDBO, userSettings);
}
}
}
I've also changed the controller code to user the CustomUserPrincipal object instead of #SessionAttributes:
In ViewController:
#RequestMapping(value="/", method=RequestMethod.GET)
public String home(ModelMap model) {
CustomUserPrincipal userPrincipal = authenticationHelpers.getUserPrincipal();
UserSettings userSettings = userPrincipal.getUserSettings();
String userListenersJson = userSettings.toJson();
return "views/home";
}
In AjaxController:
#RequestMapping(value="/users/listeners/{externalId}", method=RequestMethod.DELETE)
public #ResponseBody
AjaxResponse<?> deleteListener(ModelMap model,
#PathVariable long externalId) {
CustomUserPrincipal userPrincipal = authenticationHelpers.getUserPrincipal();
UserSettings userSettings = userPrincipal.getUserSettings();
userSettings.removeListener(externalId);
return new AjaxResponse<String>(null, true);
}
I hope this helps shed some light on the issue!

Answer 1

I ran into a similar problem with #SessionAttributes. A controller had a #SessionAttributes annotation at the class level, and one of the methods handled POST requests, and included an instance of the session-managed object as an argument. This instance was saved to the database, but was re-used by subsequent requests, causing some data corruption. We had to add another method argument of type SessionStatus, and call SessionStatus.setComplete(). This caused the instance to be removed from the session, and prevented reuse and corruption. So try adding a SessionStatus instance to your controllers' handler methods, and invoke setComplete() where appropriate.
EDIT: I accidentally referenced the getter isComplete() in my initial answer; I meant to reference the setter setComplete().

Answer 2

#SessionAttributes is specific to a Controller and is not shared among several Controllers.
Instead, consider using manually session.setAttribute (class HttpSession).
You should have a look here : http://beholdtheapocalypse.blogspot.fr/2013/01/spring-mvc-framework-sessionattributes.html