Lift Framework example source code file (Msg.scala)

This example Lift Framework source code file (Msg.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lift Framework tags/keywords

dispatchit, hashmap, msgerrormeta, msgnoticemeta, msgwarningmeta, nil, nil, nodeseq, nodeseq, sessionvar, sessionvar, string, string, text

The Lift Framework Msg.scala source code

/*
 * Copyright 2007-2011 WorldWide Conferencing, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.liftweb
package builtin
package snippet

import net.liftweb.http._
import net.liftweb.http.S._
import scala.xml._
import net.liftweb.util.Helpers._
import net.liftweb.common.{Full, Empty}
import scala.collection.mutable.HashMap
import net.liftweb.http.js._
import JsCmds._

/**
 * This class is a built in snippet that allows rendering only notices (Errors, Warnings, Notices)
 * that are associated with the id provided. This snippet also renders effects configured for the
 * given id. Typically this will be used near by form fields to indicate that a certain field
 * failed the validation. For example:
 *
 * <pre name="code" class="xml">
 *   <input type="text" value="" name="132746123548765"/><lift:msg id="user_msg"/>
 * </pre>
 *
 * Additionally, you may specify additional CSS classes to be applied to each type of notice
 * using the followin attributes:
 *
 * <ul>
 *   <li>errorClass
 *   <li>warningClass
 *   <li>noticeClass
 * </ul>
 * 
 * <pre name="code" class="xml">
 *   <input type="text" value="" name="132746123548765"/><lift:msg id="user_msg"
 *                                                        errorClass="error_class"
 *                                                        warningClass="warning_class"
 *                                                        noticeClass="notice_class"/>
 * </pre>
 *
 * Notices for specific ids are set via the S.error(String,String) or S.error(String,NodeSeq)
 * methods. Global (non-id) notices are rendered via the Msgs snippet. 
 *
 * @see net.liftweb.builtin.snippet.Msgs
 * @see net.liftweb.http.S#error(String,String)
 * @see net.liftweb.http.S#error(String,NodeSeq)
 * @see net.liftweb.http.LiftRules#noticesEffects
 */
object Msg extends DispatchSnippet {
  def dispatch: DispatchIt = {
    case _ => render
  }

  /**
   * This method performs extraction of the CSS class attributes
   * as well as rendering of any messages for the given id.
   */
  def render(styles: NodeSeq): NodeSeq = {
    attr("id") match {
      case Full(id) => {
        // Extract the currently set CSS
        (attr("errorClass") or  attr("errorclass")).map(cls => MsgErrorMeta += (id -> cls))
        (attr("warningClass") or attr("warningclass")).map(cls => MsgWarningMeta += (id -> cls))
        (attr("noticeClass") or attr("noticeclass")).map(cls => MsgNoticeMeta += (id -> cls))

        renderIdMsgs(id) ++ effects(id)
      }
      case _ => NodeSeq.Empty
    }
  }

  /**
   * This method renders the <span/> for a given id's notices,
   * along with any effects configured for the id.
   *
   * @see net.liftweb.http.S#error(String,String)
   * @see net.liftweb.http.S#error(String,NodeSeq)
   * @see net.liftweb.http.LiftRules#noticesEffects
   */
  def renderIdMsgs(id : String) : NodeSeq = {
    val msgs : List[NodeSeq] = List((S.messagesById(id)(S.errors), MsgErrorMeta.get.get(id)),
                                    (S.messagesById(id)(S.warnings), MsgWarningMeta.get.get(id)),
                                    (S.messagesById(id)(S.notices), MsgNoticeMeta.get.get(id))).flatMap {
      case (msg, style) =>
        msg.toList match {
          case Nil => Nil
          case msgList => style match {
            case Some(s) => msgList.flatMap(t => <span>{t} % ("class" -> s))
            case _ => msgList flatMap ( n => n )
          }
        }
    }

    // Join multiple messages together with a comma
    val commafied = msgs match {
      case Nil => Text("")
      case spans => spans.reduceLeft {
        (output,span) => output ++ Text(", ") ++ span
      }
    }

    <span>{commafied} % ("id" -> id)
  }

  /**
   * This method renders a <script/> element that renders effects for
   * the given id.
   *
   * @see net.liftweb.builtin.snippet.Msgs#effects[T](Box[NoticeType.Value],String,T,Box[JsCmd => T])
   */
  def effects(id: String): NodeSeq = 
    Msgs.effects(Empty, id, NodeSeq.Empty, Msgs.tailScript)
}

/**
 * This SessionVar holds a map of per-id CSS classes for error notices
 * so that the AJAX and static renderers use the same formatting.
 */
object MsgErrorMeta extends SessionVar[HashMap[String, String]](new HashMap) {
    override private[liftweb] def magicSessionVar_? = true
}

/**
 * This SessionVar holds a map of per-id CSS classes for warning notices
 * so that the AJAX and static renderers use the same formatting.
 */
object MsgWarningMeta extends SessionVar[HashMap[String, String]](new HashMap) {
    override private[liftweb] def magicSessionVar_? = true
}

/**
 * This SessionVar holds a map of per-id CSS classes for notice notices
 * so that the AJAX and static renderers use the same formatting.
 */
object MsgNoticeMeta extends SessionVar[HashMap[String, String]](new HashMap) {
    override private[liftweb] def magicSessionVar_? = true
}