RequestVar is the standard way of doing this. For example
object MySharedInformation {
object myData extends RequestVar[List[Thing]](loadThings)
// ^^^^^^^^^^^ ^^^^^^^^^^
// Type of thing to store How to initialize
variable first time it's accessed
private def loadThings: List[Thing] = ...
}
class Snippet1 {
import MySharedInformation.myData
def render(ns: NodeSeq): NodeSeq = {
myData.is.map(thing => { ... })
}
}
class Snippet2 {
import MySharedInformation.myData
...
}
The lifetime of the value is during the current request processing and
any AJAX calls related to it.
If you really want to initialize it in a snippet, then use a Box with
a RequestVar, like this:
object MySharedInformation {
object myData extends RequestVar[Box[List[Thing]]](Empty)
}
class LoaderSnippet {
import MySharedInformation.myData
def render(ns: NodeSeq): NodeSeq = {
myData.set(Full(...))
}
}
class ReaderSnippet {
import MySharedInformation.myData
def render(ns: NodeSeq): NodeSeq = {
// If the data has not been loaded, default to an empty list
val data = myData.is.openOr(Nil)
...
}
}
class OtherReaderSnippet {
import MySharedInformation.myData
def render(ns: NodeSeq): NodeSeq = {
// Do two entirely different things if the data has versus
has not been loaded
myData.is match {
case Full(data) => // do something when the data has been
loaded
case _ => // do something when the data has not been loaded
}
}
}
HTH,
-Ross
On Nov 20, 2009, at 10:59 AM, Alex Black wrote:
> I've got a template page, say foobar.html, that makes a number of
> calls to functions in a snippet, e.g. mysnippet.foo1, mysnippet.foo2,
> mysnippet.foo3.
>
> I'd like to do some initial work in foo1, e.g. retrieve some data and
> do some work on it, then in foo2 and foo3 display parts of that data.
>
> Whats the easiest way to do this? I think I misunderstood the lift
> book:
>
> "That means that for each request, Lift creates a new instance of the
> snippet class to execute. Any changes you make to instance variables
> will be discarded after the request is processed."
>
> I thought this meant that for a given HTTP request, there would be one
> (and only one) instance of my snippet, so I could call several of its
> methods and they could all access the snippet's member variables,
> which would then be discarded at the end of the request.
>
> Am I going about this wrong? should I only have one snippet function
> per template?
>
> Thx
>
> - Alex
>
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