London Scala UG - Lift:Getting started with Scala

Getting started with Lift
Richard Dallaway, @d6y
richard@taykt.com

Struts Play GWT Seam

Rails Spring MVC JSF WebObjects

Grails PHP Cocoon Seaside

Stripes JAX-RS Wicket Lift

Struts Play GWT Seam

Rails Spring MVC JSF WebObjects

Grails PHP Cocoon Seaside

Stripes JAX-RS Wicket Lift

Zero Plenty
Weirdness

Versions

1.0.3 Updated Jan 2010

2.0 M2 Released Feb 2010

both for Scala 2.7.7

$ find . -name lift* -depth 2 -type d

lift-base/lift-actor lift-modules/lift-paypal
lift-base/lift-common lift-modules/lift-testkit
lift-base/lift-json lift-modules/lift-textile
lift-base/lift-util lift-modules/lift-widgets
lift-base/lift-webkit lift-modules/lift-wizard
lift-modules/lift-xmpp
lift-modules/lift-amqp
lift-modules/lift-facebook lift-persistence/lift-couchdb
lift-modules/lift-imaging lift-persistence/lift-jpa
lift-modules/lift-jta lift-persistence/lift-mapper
lift-modules/lift-ldap lift-persistence/lift-record
lift-modules/lift-machine
lift-modules/lift-oauth
lift-modules/lift-openid
lift-modules/lift-osgi

Agenda

• Part I: View ﬁrst
• Part II: Doing stuff quickly
• Part III: Ajax
• Part IV: Real time web

The time on this server is: Mon Mar 08 18:40:51 GMT 2010.

<html xmlns="http://www.w3.org/1999/xhtml">
<body>
<h1>Hello world</h1>

<p>The time on this server is:
<lift:Time.now>
time appears here
</lift:Time.now>
</p>

</body>
</html>

package com.myproject.snippet

import scala.xml.NodeSeq

class Time {

// My <lift:Time.now /> implementation:
def now(xhtml: NodeSeq) =
<span>{new java.util.Date()}</span>

}

<body>
<h1>Hello world</h1>

<lift:Time.now>
<p>It’s <when:day/> at <when:hour/>.</p>
</lift:Time.now>

</body>
</html>

package com.myproject.snippet

import scala.xml.{NodeSeq,Text}
import net.liftweb.util.Helpers._

class Time {

def now(xhtml:NodeSeq) = {
val day = "Monday"
val hour = "7 o'clock"
bind("when", xhtml,
"hour" -> <span>{hour}</span>,
"day" -> Text(day) )
}
}


<body>

<h1>Hello Canada</h1>

<lift:Olympics.results>
<table>
<table:rows>
<tr>
<td><r:country>Country here</r:country></td>
<td><r:golds>Gold medal count</r:golds></td>
</tr>
</table:rows>
</table>
</lift:Olympics.results>

</body>

</html>

package com.myprojects.snippet

import scala.xml.NodeSeq

class Olympics {

case class Golds(country: String, medals: Int)

def results(xhtml: NodeSeq) = {

val vancouver = Golds("CAN", 14) :: Golds("GER", 10) ::
Golds("GBR", 1) :: Nil

// <table:rows> <r:country/> <r:golds/> </table:rows>
bind("table", xhtml,
! ! "rows" -> vancouver.flatMap( gold =>
bind("r", chooseTemplate("table", "rows", xhtml),
"country" -> gold.country,
"golds" -> gold.medals )
)
)
}

}

$ mvn archetype:generate
-DarchetypeCatalog=http://scala-tools.org/
Choose archetype:
1: http://scala-tools.org/ -> scala-archetype-simple (A simple scala project)
2: http://scala-tools.org/ -> lift-archetype-blank (A blank/empty liftweb project)
3: http://scala-tools.org/ -> lift-archetype-basic (A basic liftweb project (with DB, css, ...))
Choose a number: (1/2/3):

$ mvn archetype:generate
-DarchetypeGroupId=net.liftweb
-DarchetypeArtifactId=lift-archetype-blank
-DarchetypeVersion=2.0-M2
-DremoteRepositories=http://scala-tools.org/repo-releases
-DgroupId=com.example.proj

package com.brightonbloggers.admin.model

import net.liftweb.common._
import net.liftweb.util._
import net.liftweb.mapper._
import net.liftweb.http._

class Blog extends LongKeyedMapper[Blog] with IdPK {

def getSingleton = Blog

object title extends MappedString(this, 20)

object url extends MappedString(this, 100) {
override def validations = isUrl _ :: super.validations
}

def isUrl(u:String) = if (url startsWith "http")
! ! ! ! ! ! ! Nil
! ! ! ! ! ! else
! ! ! ! ! ! ! List(FieldError(url, S.?("field.url.error")))
}

object Blog extends Blog with LongKeyedMetaMapper[Blog] with CRUDify[Long,Blog]
{
}

<lift:surround with="default" at="content">

<h1>Ajax blog</h1>

<div id="list">

<lift:Blogs.list>

<ul>
<directory:entry />
</ul>

<directory:new_blog />

</lift:Blogs.list>

</div>

</lift:surround>

import com.brightonbloggers.admin.model.Blog

import scala.xml._
import net.liftweb.http.SHtml._
import net.liftweb.http.js.JsCmds._
import net.liftweb.http.S._

class Blogs {

def list(xhtml: NodeSeq): NodeSeq = {
!
def add_new_blog(s: String) = {
Blog.create.url(s).title(s).save
SetHtml( "list", list(xhtml) )
}

bind("directory", xhtml,
! ! "entry" -> Blog.findAll().flatMap(
b => <li>{b.url}</li> ),
! ! "new_blog" -> ajaxText("", add_new_blog _)
)

}

}

package com.brightonbloggers.admin.snippet

import com.brightonbloggers.admin.model.Blog

import scala.xml._
import net.liftweb.http.SHtml._
import net.liftweb.http.S._

class Blogs {

!
def add_new_blog(s: String) = {
Blog.create.url(s).title(s).save
SetHtml("list", list(xhtml) )
}

def update_blog(blog: Blog)(new_value: String) = {
blog.url(new_value).save
SetHtml("list", list(xhtml) )
}

def click_to_edit(blog: Blog) : NodeSeq =
!! swappable( <li>{blog.url}</li>,
!! ! ajaxText(blog.url, update_blog(blog) _ ) )

!! "entry" -> Blog.findAll().flatMap( click_to_edit _ ),
!! "new_blog" -> ajaxText("", add_new_blog _)
)

}
}

User Activity

Client Processing

Comet Event Bus
Event
Initialization

Data Push
Event Displa
y
Data Push
Displa
y

Event
Data Push
Event Displa
y
Data Push
Displa
y

Event
Data Push
Server-Side Processing

Displa
y

!
def countable(blog: Blog) : NodeSeq =
! <li>{link("/static/list",
() => { StatsServer ! blog },
Text(blog.url)) }</li>

! ! "entry" -> Blog.findAll().flatMap(countable _)
)

package com.brightonbloggers.admin.comet

import net.liftweb.http._
import net.liftweb.http.js._
import net.liftweb.actor._
import scala.xml._

object StatsServer extends LiftActor with ListenerManager {

var count = 0

override def lowPriority = {
case b =>
count = count + 1
updateListeners()
}

def createUpdate = count
}

// <lift:comet type=”StatsWatch” />
class StatsWatch extends CometActor with CometListenee {

def registerWith = StatsServer

override def render = <div id="total">0</div>

override def lowPriority = {
case count: Int =>
partialUpdate(SetHtml("total", Text(count.toString)))
}

}

Thank you.
• Lift book: http://groups.google.com/group/
the-lift-book
• Liftweb.net: Wiki, mailing list, getting started
guide
• Visit lsug.org, join the meetup.com group

apress discount code

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Kevin
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London Scala UG - Lift:Getting started with Scala

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