Layout snippet that excludes the layout for AJAX requests + JS for retaining functions for AJAX loaded pages.

Layout.scala

package com.openstudy { package snippet {
  import scala.xml._

  import net.liftweb.http.S
  import net.liftweb.util.Helpers._

  class Layout {
    def render(xhtml:NodeSeq) = {
      if (S.request.map(_.ajax_?) == Full(true)) {
        S.skipXmlHeader = true
        S.skipDocType = true

        /**
         * We add a data-gc-version attribute to the root element. This
         * attribute is read client-side to send a __Lift_GC message back to
         * the server to make sure we don't garbage collect fields associated
         * with this page. This page is rendered under a different version than
         * the original page itself, so we have to avoid garbage collecting
         * this page's version in addition to the base page.
         */
        val rendered = xhtml match {
          case group:Group => 
            group.find {
              case e:Elem => true
              case _ => false
            }.map {
              case e:Elem => e % ("data-gc-version" -> S.renderVersion)
            } getOrElse group
          case other => other
        }

        S.session.map { liftSession =>
          liftSession.processSurroundAndInclude("xhr page", rendered)
        } openOr rendered
      } else {
        val layoutFile =
          S.attr("is").map { file =>
            file.startsWith("/") ? file.substring(1) | ("layouts-hidden/" + file)
          } openOr "default"
        val insertionPoint = S.attr("at") openOr "content"

        <lift:surround with={layoutFile} at={insertionPoint}>{xhtml}</lift:surround>
      }
    }
  }
} }

lift-ajax-adjustments.coffee

# When we load entire pages via AJAX (for example, updates), Lift gives
# them a different GC id. Lift's GC throws away closures for fields and
# such after they haven't been seen on a page for a certain amount of
# time (10 minutes by default).
#
# Server-side, such renderings add an attribute to the base element,
# data-gc-version, that provide the Lift GC id for these pages. Here, we
# look for such ids and make sure to issue GC requests to Lift so that
# Lift doesn't erroneously clean up our closures.
if liftAjax?
  lift_registerGC = liftAjax.lift_registerGC
  lift_successRegisterGC = liftAjax.lift_successRegisterGC
  lift_failRegisterGC = liftAjax.lift_failRegisterGC

  successRegistered = false
  failRegistered = false

  liftAjax.lift_successRegisterGC = ->
    unless successRegistered
      successRegistered = true
      lift_successRegisterGC()

  liftAjax.lift_failRegisterGC = ->
    unless failRegistered
      failRegistered = true
      lift_failRegisterGC()

  liftAjax.lift_registerGC = ->
    successRegistered = failRegistered = false

    lift_originalPage = lift_page

    lift_registerGC()
    gcIds = {}
    gcIds[$(elt).data('gc-version')] = true for elt in $('*[data-gc-version]')

    for gcId of gcIds
      lift_page = gcId
      lift_registerGC()

    lift_page = lift_originalPage