Install
sudo gem install nokogiri
Contribute
github.com/sparklemotion/nokogiri

An HTML, XML, SAX, & Reader parser with the ability to search documents via XPath or CSS3 selectors… and much more

Nokogiri

Modifying an HTML / XML Document

Changing text contents

Assuming we have the following HTML document:

@doc = Nokogiri::HTML::DocumentFragment.parse <<-EOHTML
<body>
  <h1>Three's Company</h1>
  <div>A love triangle.</div>
</body>
EOHTML

Let’s change the header’s text contents:

h1 = @doc.at_css "h1"
h1.content = "Snap, Crackle and Pop"

@doc.to_html
# => "<body>
#   <h1>Snap, Crackle and Pop</h1>
#   <div>A love triangle.</div>
# </body>"

Pow!

Moving nodes

The simplest method of moving a node is assign its parent:

h1  = @doc.at_css "h1"
div = @doc.at_css "div"
h1.parent = div

@doc.to_html
# => "<body>
#   
#   <div>A love triangle.<h1>Three's Company</h1>
# </div>
# </body>"

But you could also arrange it next to other nodes:

div.add_next_sibling(h1)

@doc.to_html
# => "<body>
#   
#   <div>A love triangle.</div>
# <h1>Three's Company</h1>
# </body>"

Modifying Nodes and Attributes

h1.name = 'h2'
h1['class'] = 'show-title'

@doc.to_html
# => "<body>
#   <h2 class="show-title">Three's Company</h2>
#   <div>A love triangle.</div>
# </body>"

Creating new nodes

h3 = Nokogiri::XML::Node.new "h3", @doc
h3.content = "1977 - 1984"
h1.add_next_sibling(h3)

@doc.to_html
# => "<body>
#   <h1>Three's Company</h1>
# <h3>1977 - 1984</h3>
#   <div>A love triangle.</div>
# </body>"

Wrapping a NodeSet

If you wanted to wrap new HTML around each node in a Nodeset, here’s an example of how to do it:

nodes = @doc.css "h1,div"
wrapper = nodes.wrap("<div class='container'></div>")

@doc.to_html
# => "<body>
#   <div class="container"><h1>Three's Company</h1></div>
#   <div class="container"><div>A love triangle.</div></div>
# </body>"

Adding a Processing Instruction

(like <?xml-stylesheet?>)

If you want to add a processing instruction (a.k.a. “PI node”), like an xml-stylesheet declaration, you should first create the node using Nokogiri::XML::ProcessingInstruction.new and then add it to the document as a previous-sibling of the root node:

doc = Nokogiri::XML "<root>foo</root>"
doc.to_xml
# => "<?xml version="1.0"?>
# <root>foo</root>
# "

pi = Nokogiri::XML::ProcessingInstruction.new(doc, "xml-stylesheet",
                                              'type="text/xsl" href="foo.xsl"')
doc.root.add_previous_sibling pi
doc.to_xml
# => "<?xml version="1.0"?>
# <?xml-stylesheet type="text/xsl" href="foo.xsl"?>
# <root>foo</root>
# "