Tutorial on using Nokogiri package to operate XML format data in Ruby, rubynokogiri

Tutorial on using Nokogiri package to operate XML format data in Ruby, rubynokogiri

Install

For Ubuntu, you need to install libxml2 and libxslt:

$ apt-get install libxml2 libxslt

Then you can:

$ gem install nokogiri

Optional
Nokogiri provides some options for parsing files. Common options include:

• Noblks: delete empty nodes
• NOENT: substitution entity
• NOERROR: Hide the error report
• STRICT: precise parsing. An error is thrown when an exception occurs during file parsing.
• NONET: Disables any network connection during resolution.

Optional usage example (called by block ):

doc = Nokogiri::XML(File.open("blossom.xml")) do |config|config.strict.nonetend

Or

doc = Nokogiri::XML(File.open("blossom.xml")) do |config|config.options = Nokogiri::XML::ParseOptions::STRICT | Nokogiri::XML::ParseOptions::NONETend

Analysis

It can be parsed from files, strings, URLs, etc. These two methods depend on Nokogiri: HTML, Nokogiri: XML:

Read string:

html_doc = Nokogiri::HTML("
Read files:

f = File.open("blossom.xml")doc = Nokogiri::XML(f)f.close
Read URL:

require 'open-uri'doc = Nokogiri::HTML(open("http://www.threescompany.com/"))
Search for nodes
You can use XPATH and CSS selector to search: for example, to specify an XML:
<books> <book> <title>Stars</title> </book> <book> <title>Moon</title> </book></books>
Xpath:
@doc.xpath("//title")
Css:
@doc.css("book title")
Modify node content
title = @doc.css("book title").firstotitle.content = 'new title'puts @doc.to_html# =>... <title>new title</title>...
Modify node Structure
First_title = @ doc. at_css ('title') second_book = @doc.css ('book '). last # You can place the first title in the second book first_title.parent = second_book. Second_book.add_next_sibling (first_title) # You can also modify the corresponding classfirst_title.name = 'h2 'first _ title ['class'] = 'Red _ color' puts @ doc. to_html #=> 



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