I've already searched via google and on stackoverflow, but could not find any similar problem to mine.
In my project I'm handling a ViewExpiredException properly and show a custom page to the user that the current session has timed out. This works great, but I want to do something BEFORE this message gets shown to the user. Actually I'm working with 2 different sessions here, one on the frontend side and one on the backend, so the idea is to NOT start a new backend session when the current one timed out.
Is there any possibility to fetch the ViewExpiredException while I'm inside the doFilter method, so I do not start a new backend session (simply because it is not needed)? Or is there any other way?
I already tried to fetch the current context via
FacesContext fc = FacesContext.getCurrentInstance();
But obviously the context is null, because the session timed out.
Inside the ExceptionHandlerWrapper I have access to the UnhandledExceptionQueuedEvents, but this does not help me here since I need this information earlier.
I hope I made my problem clear enough.
Thanks in advance for any help!
Regards
Sebastian
Generally ViewExpiredException is thrown when a POST request is fired while the session is timed out. So, this should do in the filter:
boolean post = "POST".equals(request.getMethod());
boolean timedout = request.getRequestedSessionId() != null && !request.isRequestedSessionIdValid();
if (post && timedout) {
// JSF will guaranteed throw ViewExpiredException when state saving is set to server.
}
But this does not cover all possible cases. ViewExpiredException can also occur when the session hasn't timed out. For example, when the client has passed an invalid javax.faces.ViewState parameter, or when the associated view has been pruned from the LRU map which can by default hold 15 views. This is however not detectable inside a servlet filter before FilterChain#doFilter() is called. You really need to be inside the JSF context. You could do the backend session creating job in a PhaseListener. E.g. in beforephase of apply request values phase, which is guaranteed to be invoked only when there's a vaild view.
By the way, the FacesContext is not null in the filter because the session has timed out, but because the FacesServlet, the one responsible for creating it, hasn't been invoked yet at that point. You know, filters run before servlets.
Related
Right now we are storing the session in map. So very first time , when we create session, it is possible that the session got created ,but due to some issue ,it immediately disconnected and logged out.
After some time, being the sessionId present in map, we are calling just lookup for that session and call logOn() . It should call my overridden logon() method which is not happening. Can anyone tell me the the possible clause and how to handle this ?when I see the logs, it's showing EndOfStream occurred,disconnecting.
private void doSomething(someProcessModel process){
CustomerModel customer = process.getCustomerModel();
customer.getFoos().stream()
.filter(foo -> foo.getCountryCode().equals(process.getCountryCode()))
.findFirst()
.ifPresent(foo -> {
if(foo.getSomeNumber() == null){
foo.setSomeNumber("1234567");
modelService.save(foo);
}
});
}
As seen in the code snippet above, I have a 'CustomerModel' that has an attribute 'Foos'. It's a one-to-many relationship. As you can see I have done some filtering and in the end, I want to update the value of 'someNumber' attribute of 'Foo' if it is null. I've confirmed that everything is working as the "someNumber" attribute's value is updated during the debugging. It doesn't save at all as I have done my checking in the HMC. I have also validated that the Interceptor doesn't have any condition that would throw an error. There is nothing being shown in the log either.
I am wondering is it a legal approach to do the "modelService.save()' inside the 'ifPresent()' method? What could be the possible issue here?
I have found the root cause now as I have face the same issue again.
Context to my original question
To give more context to my original question, the #doSomething method resides in a Hybris Business Process action class and I have ended the action prematurely while I am debugging it (by stopping the debugging) once the #doSomething method is ran.
Root cause
The mentioned problem happened when I was debugging the action class. I assumed that the ModelService#save will persist the current state of the business process once it has been ran. However, the Hybris OOTB business process will do a rollback if there is any error (and I believe it was caused by me stopping the debugging half-way).
SAP Commerce Documentation:
All actions are performed inside their own transaction. This means that changes made inside the action bean run method are rolled back in case of an error.
Solution
Let the action runs completely!
Good to know
Based on the SAP Documentation and this blog post, there will be times that we will need to bypass a business process rollback even though there is an exception being thrown and there are ways to achieve that. More info can be found in this SAP Commerce Documentation and the mentioned blog post.
However, in some circumstances it may be required to let a business exception reach the outside but also commit the transaction and deal with the exception outside. Therefore, it is possible to make the task engine not roll back the changes made during a task which failed.
You have to be cautious with a list in models as they are immutable, you have to set the whole new list. Also you called save only on a particular model, which changes its Jalo reference, that's why your list is not updated. Mutating stream and collecting it in the end will create new list that's why you can stream over the list directly from the model.
private void doSomething(someProcessModel process){
CustomerModel customer = process.getCustomerModel();
ArrayList<FooModel> foos = doSomethingOnFoos(customer.getFoos());
customer.setFoos(foos);
modelService.saveAll(foos, customer);
}
//compare the value you know exists with something that might be NULL as equals can handle that, but not the other way around
private ArrayList<FooModel> doSomethingOnFoos(ArrayList<FooModel> fooList) {
return fooList.stream()
.filter(Objects::nonNull)
.filter(foo -> process.getCountryCode().equals(foo.getCountryCode()))
.filter(foo -> Objects.isNull(foo.getSomeNumber()))
.map(foo -> foo.setSomeNumber(1234))
.collect(toList());
}
We have a custom tag similar to g:set which sets the current user into PageScope <n:currentUser var=”foobar”> It works great until we have a flowaction.
For a flowaction view state, which uses above tag, it will throw Lazy initialization exception “could not initialize proxy - no Session”, even though the user is loaded in the same request and set in pagescope.
Doesn’t webflow respect OpenSessionInView ! What’s going wrong here.
What could be the solution other then eager fetching and passing the modal explicitly.
(The tag is in a layout actually, which is applied for the view of the view state)
UPDATE
I just noticed, that even when accessing the the object right after it is loaded, it still gives the same error. So its not PageScope things causing the issue
Inside the tag
User user = User.get(x)
println user.foo.bar gives the same error
It looks like, for flow actions, session isn't kept open at all, and it seems to close right after the operation is complete.
Thanks
I've seen this error before, and not related to the webflow, but using a tag inside a layout. In this case the layout is handled after the session is closed and you need to create a new session manually.
def currentUser = { attrs ->
User.withTransaction {
User user = User.get(x)
}
}
The JIRA have the status won't fix because is not a good practice to make GORM queries inside TagLib's.
In my app, I have a code like this:
// 1
Foo.get(123).example = "my example" // as expected, don't change value in db
// 2
Foo.get(123).bars.each { bar ->
bar.value *= -1 // it's changing "value" field in database!! WHY?
}
note: Foo and Bar are tables in my DB
Why is gorm saving in database is second case?
I don't have any save() method in code.
Tks
SOLVED:
I need to use read() to get a readonly session.
(Foo.discard() also works)
Doc: http://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20%28GORM%29.html#5.1.1%20Basic%20CRUD
(In the first case, I guess I made mistest)
Both should save, so the first example appears to be a bug. Grails requests run in the context of an OpenSessionInView interceptor. This opens a Hibernate session at the beginning of each request and binds it to the thread, and flushes and closes it at the end of the request. This helps a lot with lazy loading, but can have unexpected consequences like you're seeing.
Although you're not explicitly saving, the logic in the Hibernate flush involves finding all attached instances that have been modified and pushing the updates to the database. This is a performance optimization since if each change had been pushed it would slow things down. So everything that can wait until a flush is queued up.
So the only time you need to explicitly save is for new instances, and when you want to check validation errors.
I am using valueUnbound method of HttpSessionBindingListener to release lock(an entry from the database), before session is about to expire:
#Override
public void valueUnbound(HttpSessionBindingEvent event) {
String user = (String) event.getSession().getAttribute("currentUsr");
removeLock(user);
}
When the lock is set, I am setting up the username as a session variable.
I need this "username" in my remove lock method. But the getAttribute is throwing an exception:
java.lang.IllegalStateException: getAttribute: Session already invalidated
I need help in getting the session variable?? or is there any other way to get the username?
No, since session has been invalidated.
Although, I figured out the solution, I am setting the attribute via servlet context in
valueBound method and getting it through the : event.getSession().getServletContext().getAttribute("cUser");
it works fine. Thank You EJP
I got your point EJP, you are right , I am making it complex, I can get it from event.getValue() . +1 to your answer, Thank You.
Although, I figured out the solution, I am setting the attribute via servlet context in valueBound method and getting it through the : event.getSession().getServletContext().getAttribute("cUser");
So.. You are storing session scoped data in the application scope. Do you realize that this way the data is shared among all visitors of the webapp? Visitor X would then see the attribute set by visitor Y which has visited the website at a later moment. It makes the problem only worse.
Anyway, as to the concrete problem, as the exception message is trying to tell you, the session has already been invalidated at that point. There are two ways to solve this:
Make currentUsr a property of the class which is implementing HttpSessionBindingListener, so that you don't need to grab it as a distinct session attribute.
Use a HttpSessionListener instead. The sessionDestroyed() method is called right before invalidation, so you should still have access to all attributes.