I wonder why this was not implemented in trinidad's base classes/interfaces in a generic way?
-----Original Message----- From: Adam Winer [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 13, 2007 9:26 PM To: MyFaces Discussion Subject: Re: [Trinidad] Page flow scope and Back button On 6/13/07, D. Cardon <[EMAIL PROTECTED]> wrote: > Thanks for the tip! That makes a lot of sense to me, but I'm a little > confused about > implementation. Does it make a difference 'when' in the lifecycle I set the > variables? > > For example, suppose the user enters the URL for my create page: */create.jsf > Then, there will be no attributes stored on the page. So, I create them, but > that occurs > in the render response phase of the page: That's the problem! It's a gotcha with page flow scope: if you wait until render response to add something, it gets dropped. I think there's a logged warning, but I'm not 100% sure of that. The reason for this is that we generate tokens lazily - we don't want to add a pageflowscope token unless absolutely necessary - but if you add it in render response, we've likely already sent the postback URL down to the client. -- Adam > > RequestContext.getCurrentInstance().getPageFlowScope().put("createdVar", > Boolean.FALSE); > Boolean [] createdArr = new Boolean[ 1 ]; > createdArr[ 0 ] = Boolean.FALSE; > RequestContext.getCurrentInstance().getPageFlowScope().put("createdArr", > createdArr); > > Then, when the user presses 'save' on the page, then the save method runs, in > which I update the > variables: > > RequestContext context = RequestContext.getCurrentInstance(); > context.getPageFlowScope().put("createdVar", Boolean.TRUE); > Boolean [] createdArr = (Boolean []) > context.getPageFlowScope().get("createdArr"); > createdArr[ 0 ] = Boolean.TRUE; > > When I press the 'back' button, then neither of these attributes exist on the > page--it's as though > the user had re-entered the page URL. > > So, I think I'm missing an important piece--how do I make sure the page > attributes are stored on > the page to begin with? or is there no way to do that? > > Thanks again for your help, > > --David > > --- Adam Winer <[EMAIL PROTECTED]> wrote: > > > Sure, what you do is: > > - Store a token - Integer, String, enum, anything you want, that indicates > > what page you're on, just like you're doing now. As you know, this will be > > restore when the back button is hit. > > > > - In addition to storing that token right on the pageFlowScope, also set it > > into a one-element array on the pageFlowScope - but don't create a new array > > each time, just keep writing into that first element. > > > > The one-element array will *not* be restored to its prior state, because > > it's still the same instance. Consequently, when you go back a page, you'll > > see that the token directly on the page won't match the token within the > > array. Back button detected! > > > > You could encapsulate this strategy into a reusable object if desired. > > > > -- Adam > > > > > > > > On 6/11/07, D. Cardon <[EMAIL PROTECTED]> wrote: > > > > > > Thanks, that clarifies the documentation. > > > > > > So, my follow-up question would be: Is there any way that I can detect in > > > Trinidad that the user > > > has gone from one page to the next one and then back again? > > > > > > Thank you for your help, > > > > > > --David > > > > > > --- Adam Winer <[EMAIL PROTECTED]> wrote: > > > > > > > On 6/8/07, D. Cardon <[EMAIL PROTECTED]> wrote: > > > > > Hi *, > > > > > > > > > > I'm a little uncertain about how the pageFlowScope interacts with the > > > browser's Back button. > > > > The > > > > > documentation states: > > > > > > > > > > "...clicking the Back button will automatically reset the page flow > > > scope to its original > > > > > state." > > > > > > > > > > Which 'original state' is this referring to? > > > > > > > > > > For example, suppose I have this situation: > > > > > > > > > > I have a wizard application. On the first page of the wizard, the > > > user should enter a > > > > username > > > > > and password and then proceed to the next page of the wizard. > > > > > > > > > > When the first page of the wizard loads, the username and password > > > fields may be entered into. > > > > > The page that takes the user to the first wizard page creates a "mode" > > > variable in the page > > > > flow > > > > > scope and sets it to "create". > > > > > > > > > > After entering valid information, the user presses the "next" button > > > on the wizard. In > > > > processing > > > > > the command button, the code sets the page flow scope variable "mode" > > > to "wizard". > > > > > > > > > > When on the second page of the wizard, the user then presses the > > > "back" button. What is the > > > > value > > > > > of the "mode" variable in the page flow scope? "create" or "wizard"? > > > > > > > > It's "create". > > > > > > > > -- Adam > > > > > > > > > > > > > > I would like to prevent the user from re-entering the username and > > > password after browsing > > > > "back" > > > > > to the first page of the wizard. I thought I could use the > > > pageFlowScope to do that, but > > > > maybe > > > > > there is a better way. Any suggestions? > > > > > > > > > > Thanks, > > > > > > > > > > --David > > > > > > > > > > > > > > > > > > > > > > > ____________________________________________________________________________________ > > > > > Get the free Yahoo! toolbar and rest assured with the added security > > > of spyware protection. > > > > > http://new.toolbar.yahoo.com/toolbar/features/norton/index.php > > > > > > > > > > > > > > > > > > > > > > > > > > > ____________________________________________________________________________________ > > > Don't pick lemons. > > > See all the new 2007 cars at Yahoo! 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