Ruby/XML/XPath

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Содержание

Count how many fish are inside the large fish.

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
 
p REXML::XPath.first(doc, "count(//fish[@size="large"][1]//*fish)")



each loop on element

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
p doc.elements.each("//fish") { |f| puts f.attribute("color") }



Find the color attributes of all small fish.

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
 
p REXML::XPath.match(doc, "//fish[@size="small"]/@color")



Find the second green element.

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
 
p REXML::XPath.match(doc, "//[@color="green"]")[1]



Get the first element and first child

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
 
doc.elements[1]
# => <aquarium> ... </>
doc.children[0]
# => <aquarium> ... </>



Get XPath from node

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
p red_fish = doc.children[0]
 
p red_fish.xpath
 
p REXML::XPath.first(doc, red_fish.xpath)



Navigating a Document with XPath

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"/>



Pass xml node to a method

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
def describe(fish)
  "#{fish.attribute("size")} #{fish.attribute("color")} fish"
end
REXML::XPath.each(doc, "//fish/fish") do |fish|
  puts "#{describe(fish.parent)} #{describe(fish)}."
end



REXML::XPath.match(doc, "//[@color="green"]")

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.match(doc, "//[@color="green"]")
# => [<fish size="small" color="green"> ... </>, <algae color="green"/>]



Search element by XPath

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
p doc.elements["//fish"]
# => <fish size="small" color="blue"/>
Источник — «http://www.wiki.crossplatform.ru/index.php/Ruby/XML/XPath»