This page contains automated test results for code from O'Reilly's Ruby Cookbook. If this code looks interesting or useful, you might want to buy the whole book.

Navigating a Document with XPath
CodeExpectedActual
xml = %{
<aquarium>
 <fish color="blue" size="small" />
 <fish color="orange" size="large">
   <fish color="green" size="small">
    <fish color="red" size="tiny" />
   </fish>
 </fish>
 <decoration type="castle" style="gaudy">
  <algae color="green" />
 </decoration>
</aquarium>}
require 'rexml/document'
doc = REXML::Document.new xml
REXML::XPath.first(doc, '//fish')
<fish size='small' color='blue'/> <fish size='small' color='blue'/> 
REXML::XPath.match(doc, '//[@color="green"]')
 [<fish size='small' color='green'> ... </>, <algae color='green'/>] [<fish size='small' color='green'> ... </>, <algae color='green'/>] 
def describe(fish)
  "#{fish.attribute('size')} #{fish.attribute('color')} fish"
end
REXML::XPath.each(doc, '//fish/fish') do |fish|
  puts "The #{describe(fish.parent)} has eaten the #{describe(fish)}."
end
 
The large orange fish has eaten the small green fish.
The small green fish has eaten the tiny red fish.
 
The large orange fish has eaten the small green fish.
The small green fish has eaten the tiny red fish.
 
red_fish = doc.children[0].children[3].children[1].children[1]
 <fish size='tiny' color='red'/> <fish size='tiny' color='red'/> 
red_fish.xpath
 "/aquarium/fish[2]/fish/fish" "/aquarium/fish[2]/fish/fish" 
REXML::XPath.first(doc, red_fish.xpath)
 <fish size='tiny' color='red'/> <fish size='tiny' color='red'/> 
REXML::XPath.match(doc, '//[@color="green"]')[1]
 <algae color='green'/> <algae color='green'/> 
REXML::XPath.match(doc, '//fish[@size="small"]/@color')
 [color='blue', color='green'] [color='blue', color='green'] 
REXML::XPath.first(doc, "count(//fish[@size='large'][1]//*fish)")
 2 2 
doc.elements.each('//fish') { |f| puts f.attribute('color') }
 
blue
orange
green
red
 
blue
orange
green
red
 
doc.elements['//fish']
 <fish size='small' color='blue'/> <fish size='small' color='blue'/> 
doc.elements[1]
 <aquarium> ... </> <aquarium> ... </> 
doc.children[0]
 <aquarium> ... </> <aquarium> ... </>