Tutorial on using Nokogiri packages in Ruby to manipulate XML format data _ruby topics

Installation

For Ubuntu, you need to install LIBXML2, libxslt these two components:

$ apt-get Install LIBXML2 libxslt

Then you can:

$ gem Install Nokogiri

Available options
Nokogiri provides some options for parsing files, which are commonly used:

• Noblanks: Delete Empty node
• Noent: Alternative Entities
• NoError: Hide Error Reporting
• STRICT: Accurate parsing, throwing an error when parsing to a file exception
• Nonet: Disables any network connections during parsing.

Options can be used as examples (via block invocation):

doc = Nokogiri::xml (File.Open ("Blossom.xml")) do |config|
Config.strict.nonet End

Or

doc = Nokogiri::xml (File.Open ("Blossom.xml")) do |config|
Config.options = nokogiri::xml::P arseoptions::strict | Nokogiri::xml::P arseoptions::nonet End

Analytical

Can be parsed from files, strings, URLs, and so on. By these two methods nokogiri::html, Nokogiri::xml:

Read string:

Html_doc = nokogiri::html (" 
 

Read file:

f = File.Open ("Blossom.xml")
doc = Nokogiri::xml (f)
F.close

Read URL:

Require ' Open-uri '
doc = nokogiri::html (open ("http://www.threescompany.com/"))

Finding nodes

You can search using XPath and CSS selector: for example, given 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 Contents

title = @doc. CSS ("book title") Firsto
title.content = ' new title '
puts @doc. to_html

# =>
...
 <title>new title</title>
...

Modifying the structure of a node

First_title = @doc. At_css (' title ')
Second_book = @doc. css (' book '). Last

# You can put the first title in the second book
First_ Title.parent = Second_book

# can also be placed freely.
second_book.add_next_sibling (first_title)

# can also modify the corresponding class
first_title.name = ' H2 '
first_title[' Class ']= ' Red_color '
puts @doc. to_html # =>