lift json autocomplete snippet

gistfile1.scala

import net.liftweb.http._
import S._
import js._
import JsCmds._
import JE._
import net.liftweb.textile._
import net.liftweb.common._
import net.liftweb.util._
import Helpers._
import scala.xml._
import net.liftweb.json._
import net.liftweb.json.JsonParser._
import com.papasofokli.snippet.JsonAutocomplete._
import net.liftweb.json.Serialization.{ read, write }

class JsonAutocomplete extends Loggable {

  /**
   * Create the json call, the createJsonFunc takes a partial function that
   * handles the incoming request.
   */
  val (call : JsonCall, jsCmd : JsCmd) = S.createJsonFunc(receiveJson)

  /**
   * Partial function that takes care of the incoming request and redirects to the corresponding handler,
   * Here you are matching directly on the json object defined bellow, you can have various case classes
   * and respond accordingly for each request. Hhere i have only 2 kinds of json request, everything
   * else goes to the log
   */
  def receiveJson : PartialFunction[JsonAST.JValue, JsCmd] = {
    case st : JsonAST.JValue ⇒ st.extractOpt[SearchTerm] match {
      case Some(SearchTerm(term)) ⇒ findTerms(term)
      case None ⇒ st.extract[IdNameCategory] match {
        case idc : IdNameCategory ⇒ handleIdNameCategory(idc)
      }
    }
    case any ⇒ logger.info("anything else goes to the log" + any.toString)
  }

  /**
   * Create a javascript to call the function to call the server with the right parameters,
   * unfortunately i cannot use the generated one since it doesn't provide the success function
   */
  val functionDef = JsRaw("function " +
    call.funcId + "(obj, onSuccess, onError) {liftAjax.lift_ajaxHandler('" +
    call.funcId + "='+ encodeURIComponent(JSON.stringify(obj)), onSuccess, onError);}")

  /**
   * Add the implicit formats for the de/serialization
   */
  implicit val formats = DefaultFormats

  /**
   * My simple find function simply returns the value i need to show on the client.
   * Here i am using the fantastic lift json support to serialize the case class
   * and send it. The only problem was i could not find a way to send back a json object.
   */
  def findTerms(term : String) : JsCmd = {
    val items = dropDownList.filter(_.value.contains(term)) take 10
    val ast = net.liftweb.json.Extraction.decompose(items)
    JsRaw(write(ast))
  }

  /**
   * Simple handler, can write to database or anything else, now i am just sending an alert.
   */
  def handleIdNameCategory(idc : IdNameCategory) : JsCmd = Alert("received " + idc.toString)

  /**
   * Render function simple replaces the script
   */
  def render : CssSel = script

  /**
   * Register the callbacks on the autocomplete, very similar to the original code from
   * jQueryUI autocomplete
   */
  def script : CssSel = "#script" #> Script(functionDef & JsRaw("""
  $(function() {
    var items = [];
    function log( message ) {
      $( "<div/>" ).text( message ).prependTo( "#log" );
	  $( "#log" ).scrollTop( 0 );
    }
		  
    $( "#city" ).autocomplete({
      delay: 1000,
	  source:  function( request, response ) {
         // I had to do this so i can pass the success and on error functions
         """ + call.funcId + """({'term': request.term },
         //On Success
         function(items){
           // Unfortunately i had to make this hack since i could not return a json from my snippet
           items = items.replace(/[\n;]/g, "");
           response(JSON.parse(items));
         }, 
         //On error
         function(){
           items =[]; 
           response(items)}
         );
    },""" +
    """
	   minLength: 2,
	  select: function( event, ui ) {
    """ +
    call.funcId + "(ui.item);" +
    """
      },
      open: function() {
        $( this ).removeClass( "ui-corner-all" ).addClass( "ui-corner-top" );
      },
      close: function() {
        $( this ).removeClass( "ui-corner-top" ).addClass( "ui-corner-all" );
      }
    });
  });
"""))
}

object JsonAutocomplete {

  /**
   * Case classes to be used for the messages between the client and server, very easy to
   * serialize and parse
   */
  case class IdNameCategory(val label : String, val value : String, val category : String)

  /**
   * Simple query for a search in the snippet
   */
  case class SearchTerm(val term : String)

  /**
   * Generate some items to check how it works
   */
  val dropDownList = for (i ← 0 to 8000) yield IdNameCategory("item" + i, "item" + i, "cat" + (i % 5))
}