Lift Cookbook

Chapter 2. HTML

Generating HTML is often a major component of web applications. This chapter is concerned with Lift’s View First approach and use of CSS Selectors. Later chapters focus more specifically on form processing, REST web services, JavaScript, Ajax, and Comet.

Code for this chapter is at https://github.com/LiftCookbook/cookbook_html.

Testing and Debugging CSS Selectors

Problem

You want to explore or debug CSS selectors interactively.

Solution

You can use the Scala REPL to run your CSS selectors.

Here’s an example where we test out a CSS selector that adds an href attribute to a link. Start from within SBT and use the console command to get into the REPL:

> console
[info] Starting scala interpreter...
[info]
Welcome to Scala version 2.9.1.final
Type in expressions to have them evaluated.
Type :help for more information.

scala> import net.liftweb.util.Helpers._
import net.liftweb.util.Helpers._

scala> val f = "a [href]" #> "http://example.org"
f: net.liftweb.util.CssSel =
  (Full(a [href]), Full(ElemSelector(a,Full(AttrSubNode(href)))))

scala> val in = <a>click me</a>
in: scala.xml.Elem = <a>click me</a>

scala> f(in)
res0: scala.xml.NodeSeq =
  NodeSeq(<a href="http://example.org">click me</a>)

The Helpers._ import brings in the CSS selector functionality, which we then exercise by creating a selector, f, calling it with a very simple template, in, and observing the result, res0.

Discussion

CSS selector transforms are one of the distinguishing features of Lift. They succinctly describe ...