Skip to content
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
Cannot retrieve contributors at this time
package code.lib.snippet
import scala.concurrent.Future
import net.liftweb.util.CssSel
import net.liftweb.util.Helpers._
import scala.xml.{NodeSeq, Text}
import net.liftweb.http.js.JsCmd
import scala.util.{Failure, Success}
import net.liftweb.common.Logger
import net.liftweb.http.{S, SHtml}
import net.liftweb.http.js.JsCmds._
import code.comet.CommandComet
object AsyncRenderer extends Logger {
// The NodeSeq to use if the Future execution fails. If you want, you can allow the users to
// pass in custom NodeSeqs for such cases.
private val DefaultFailureContent = Text("Unfortunately, this operation could not be completed.")
* This can be made made more configurable by adding more arguments. One additional
* argument could be the NodeSeq for the placeholder that's shown while the Future
* is not yet complete.
* @param renderer the Future with CssSel transforms that will be used for rendering
* your template when that Future completes.
* @param existingCometName name of a comet of type code.comet.CommandComet if such
* in instance has been already put on the page before. If not, no problem.
* @param template the original NodeSeq that was passed to your snippet instance and that
* will be transformed using the renderer that was passed to this method.
def render(renderer: Future[CssSel],
template: NodeSeq,
existingCometName: Option[String] = None): NodeSeq = {
implicit val session = S.session.openOrThrowException("An active session is required")
val cometName = existingCometName getOrElse nextFuncName
var transforms: Option[CssSel] = None
val containerId = nextFuncName
// Currently LiftSession#buildDeferredFunction doesn't take arguments, so
// whatever we want to make available to the deferred function, we have to
// do it via closures, like we are doing with the 'transforms' var here.
val renderFn = session.buildDeferredFunction { () =>
val result = transforms match {
case Some(selector) => selector(template)
case None => DefaultFailureContent
val cmd = SetHtml(containerId, result)
CommandComet.sendJsCmd(cometName, cmd)
renderer.onComplete { result =>
result match {
case Failure(ex) =>
error("An error occurred during async rendering", ex)
case Success(selector) =>
transforms = Some(selector)
} { sel =>
transforms = Some(sel)
}.recover { case ex: Throwable =>
error("An error occurred while getting messages", ex)
// If an actor wasn't setup previously, add a new one just for our
// purposes.
val actor = existingCometName match {
case Some(_) => NodeSeq.Empty
case None => CommandComet.render(cometName)
// This is the content that will be displayed before the Future is completed.
// You can take an optional NodeSeq as an argument to this method if you want
// to allow the users to customize this template.
val placeholder =
<div id={containerId}>
<img alt="progress indicator" src="/assets/images/ajax-loader.gif" />
placeholder ++ actor