Upload Component with GAE

Vaadin 6 / 7 / 8 Framework UI
1

Hi,

I’m newbie and testing Vaadin framework (great framework by the way).

While testing the upload component with AppEngine i’ve encounter a problem. I’m trying to show the upload component in 2 views but i can’t make it works. The first time that i upload a file everything is ok, but when i change to a different view and tried to upload a file it give me the next exception:

Caused by: java.lang.NullPointerException
	at com.vaadin.ui.Upload.receiveUpload(Upload.java:169)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleFileUpload(AbstractCommunicationManager.java:466)
	at com.vaadin.terminal.gwt.server.CommunicationManager.handleFileUpload(CommunicationManager.java:243)
	at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:470)

It is an exception launched by the Upload.class at this piece of code:

synchronized (application) {
            fireStarted(filename, type);
        }

I know that it is because application is null and the method getApplication() returns null when you haven’t attached the upload component to the application, but it doesn’t make any sense, the upload component is added to a layout and shown in the web browser.

I’ve tried making 2 instances of upload component and with 1 instance removing first from de old layout and adding again in the new layout.

Any idea of what i’m doing wrong?

Thanks and sorry for my english.