On Tue, Jul 14, 2009 at 11:23 AM, Ross Mellgren <dri...@gmail.com> wrote:
> The RequestVar sounds a bit more fun, but I'd rather not take your time -- > I'm sure if the SessionVar becomes onerous I can toy with that. I have some > concerns about stability of the image URLs, actually, so using a SessionVar > with some stable names seems like a better idea. > I'm interested in learning how the state works in detail in lift though, so > do you mind explaining why there might be multiple instances? I assumed that > (session, snippet class) was one-to-one with snippet instances? > Open two browser tabs and in each tab browse to: http://demo.liftweb.net/arc In the first browser tab, enter "first" and in the second enter "second". Click the submit button on each. You'll see that the state of each browser tab is separate. If you do a view source and look at the form... there's a hidden field in the form. What's happening under the covers is that the hidden field maps to a function on the server. The function tells the current Lift session that if, during the processing of the current request, Lift finds a snippet named whatever the name of the stateful snippet is named, don't create a new instance, but use the instance that the function holds. In this way, the snippet maintains state because it's the same instance (with the same instance variables, etc.) But if you have two different browser windows, each has instantiated a new stateful snippet and each of the hidden fields maps to a different function that associates different instances of the stateful snippet with the snippet name. > > -Ross > > On Jul 14, 2009, at 2:18 PM, David Pollak wrote: > > > > On Tue, Jul 14, 2009 at 10:50 AM, Ross Mellgren <dri...@gmail.com> wrote: > >> darn, I was hoping I could just get away with letting Lift manage the >> session by virtue of managing the session snippet. >> > > There may be multiple stateful snippet instances for a given stateful > snippet within the system. Figuring out which is which is a non-trivial > task for your image serving URL. > > If you really, really don't like the SessionVar idea, you can bind a > function to your /image request and that function can deposit a reference to > the current stateful snippet into a RequestVar that can be accessed during > the image serving process. If you like that answer better, give me a few > days to whip up an example. > > >> >> Thanks for the advice. >> >> -Ross >> >> On Jul 13, 2009, at 6:38 PM, David Pollak wrote: >> >> >> >> On Mon, Jul 13, 2009 at 3:21 PM, Ross Mellgren <dri...@gmail.com> wrote: >> >>> >>> Hi all, >>> >>> Is there any way to get a StatefulSnippet instance for a particular >>> class in the current session? It looks like there's machinery in S, >>> LiftRules, and LiftSession to get these but they're all marked >>> private[http]. >>> >>> I'm still getting used to Lift, so I could very well be approaching >>> this the wrong way (using a custom dispatch) -- I have a snippet which >>> manages an image editing workflow. I'd like to create a dispatch which >>> serves up the current version of the image(s) to the user, so I need >>> to dump back a raw response without any template processing. >>> >>> I could stuff the current image(s) in a SessionVar or perhaps use an >>> injector and RequestVar, perhaps? >> >> >> Your best bet is to use a SessionVar. Put the image or a pointer to how >> to get the image in a SessionVar. >> >>> >>> >>> -Ross >>> >>> >>> >>> >> >> >> -- >> Lift, the simply functional web framework http://liftweb.net >> Beginning Scala http://www.apress.com/book/view/1430219890 >> Follow me: http://twitter.com/dpp >> Git some: http://github.com/dpp >> >> >> >> >> >> >> > > > -- > Lift, the simply functional web framework http://liftweb.net > Beginning Scala http://www.apress.com/book/view/1430219890 > Follow me: http://twitter.com/dpp > Git some: http://github.com/dpp > > > > > > > > -- Lift, the simply functional web framework http://liftweb.net Beginning Scala http://www.apress.com/book/view/1430219890 Follow me: http://twitter.com/dpp Git some: http://github.com/dpp --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Lift" group. To post to this group, send email to liftweb@googlegroups.com To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/liftweb?hl=en -~----------~----~----~----~------~----~------~--~---
