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

Class Nokogiri::XML::Builder inherits from Object

Nokogiri builder can be used for building XML and HTML documents.

Synopsis:

builder = Nokogiri::XML::Builder.new do |xml|
xml.root {
  xml.products {
    xml.widget {
      xml.id_ "10"
      xml.name "Awesome widget"
    }
  }
}
end
puts builder.to_xml

Will output:

<?xml version="1.0"?>
<root>
<products>
  <widget>
    <id>10</id>
    <name>Awesome widget</name>
  </widget>
</products>
</root>

Builder scope

The builder allows two forms. When the builder is supplied with a block that has a parameter, the outside scope is maintained. This means you can access variables that are outside your builder. If you don’t need outside scope, you can use the builder without the “xml” prefix like this:

builder = Nokogiri::XML::Builder.new do
root {
  products {
    widget {
      id_ "10"
      name "Awesome widget"
    }
  }
}
end

Special Tags

The builder works by taking advantage of method_missing. Unfortunately some methods are defined in ruby that are difficult or dangerous to remove. You may want to create tags with the name “type”, “class”, and “id” for example. In that case, you can use an underscore to disambiguate your tag name from the method call.

Here is an example of using the underscore to disambiguate tag names from ruby methods:

@objects = [Object.new, Object.new, Object.new]

builder = Nokogiri::XML::Builder.new do |xml|
xml.root {
  xml.objects {
    @objects.each do |o|
      xml.object {
        xml.type_   o.type
        xml.class_  o.class.name
        xml.id_     o.id
      }
    end
  }
}
end
puts builder.to_xml

The underscore may be used with any tag name, and the last underscore will just be removed. This code will output the following XML:

<?xml version="1.0"?>
<root>
<objects>
  <object>
    <type>Object</type>
    <class>Object</class>
    <id>48390</id>
  </object>
  <object>
    <type>Object</type>
    <class>Object</class>
    <id>48380</id>
  </object>
  <object>
    <type>Object</type>
    <class>Object</class>
    <id>48370</id>
  </object>
</objects>
</root>

Tag Attributes

Tag attributes may be supplied as method arguments. Here is our previous example, but using attributes rather than tags:

@objects = [Object.new, Object.new, Object.new]

builder = Nokogiri::XML::Builder.new do |xml|
xml.root {
  xml.objects {
    @objects.each do |o|
      xml.object(:type => o.type, :class => o.class, :id => o.id)
    end
  }
}
end
puts builder.to_xml

Tag Attribute Short Cuts

A couple attribute short cuts are available when building tags. The short cuts are available by special method calls when building a tag.

This example builds an “object” tag with the class attribute “classy” and the id of “thing”:

builder = Nokogiri::XML::Builder.new do |xml|
xml.root {
  xml.objects {
    xml.object.classy.thing!
  }
}
end
puts builder.to_xml

Which will output:

<?xml version="1.0"?>
<root>
<objects>
  <object class="classy" id="thing"/>
</objects>
</root>

All other options are still supported with this syntax, including blocks and extra tag attributes.

Namespaces

Namespaces are added similarly to attributes. Nokogiri::XML::Builder assumes that when an attribute starts with “xmlns”, it is meant to be a namespace:

builder = Nokogiri::XML::Builder.new { |xml|
xml.root('xmlns' => 'default', 'xmlns:foo' => 'bar') do
  xml.tenderlove
end
}
puts builder.to_xml

Will output XML like this:

<?xml version="1.0"?>
<root xmlns:foo="bar" xmlns="default">
<tenderlove/>
</root>

Referencing declared namespaces

Tags that reference non-default namespaces (i.e. a tag “foo:bar”) can be built by using the Nokogiri::XML::Builder#[] method.

For example:

builder = Nokogiri::XML::Builder.new do |xml|
xml.root('xmlns:foo' => 'bar') {
  xml.objects {
    xml['foo'].object.classy.thing!
  }
}
end
puts builder.to_xml

Will output this XML:

<?xml version="1.0"?>
<root xmlns:foo="bar">
<objects>
  <foo:object class="classy" id="thing"/>
</objects>
</root>

Note the “foo:object” tag.

Document Types

To create a document type (DTD), access use the Builder#doc method to get the current context document. Then call Node#create_internal_subset to create the DTD node.

For example, this Ruby:

builder = Nokogiri::XML::Builder.new do |xml|
xml.doc.create_internal_subset(
  'html',
  "-//W3C//DTD HTML 4.01 Transitional//EN",
  "http://www.w3.org/TR/html4/loose.dtd"
)
xml.root do
  xml.foo
end
end

puts builder.to_xml

Will output this xml:

<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<root>
<foo/>
</root>

Attributes

context RW

A context object for use when the block has no arguments

doc RW

The current Document object being built

parent RW

The parent of the current node being built

Public Class Methods

new(options = {}) Show Source

Create a new Builder object. options are sent to the top level Document that is being built.

Building a document with a particular encoding for example:

Nokogiri::XML::Builder.new(:encoding => 'UTF-8') do |xml|
  ...
end
# File lib/nokogiri/xml/builder.rb, line 266 def initialize options = {}, root = nil, &block if root @doc = root.document @parent = root else namespace = self.class.name.split('::') namespace[-1] = 'Document' @doc = eval(namespace.join('::')).new @parent = @doc end @context = nil @arity = nil @ns = nil options.each do |k,v| @doc.send(:"#{k}=", v) end return unless block_given? @arity = block.arity if @arity <= 0 @context = eval('self', block.binding) instance_eval(&block) else yield self end @parent = @doc end
with(root, &block) Show Source

Create a builder with an existing root object. This is for use when you have an existing document that you would like to augment with builder methods. The builder context created will start with the given root node.

For example:

doc = Nokogiri::XML(open('somedoc.xml'))
Nokogiri::XML::Builder.with(doc.at('some_tag')) do |xml|
  # ... Use normal builder methods here ...
  xml.awesome # add the "awesome" tag below "some_tag"
end
# File lib/nokogiri/xml/builder.rb, line 253 def self.with root, &block new({}, root, &block) end

Public Instance Methods

<<(string) Show Source

Append the given raw XML string to the document

# File lib/nokogiri/xml/builder.rb, line 348 def << string @doc.fragment(string).children.each { |x| insert(x) } end
[](ns) Show Source

Build a tag that is associated with namespace ns. Raises an ArgumentError if ns has not been defined higher in the tree.

# File lib/nokogiri/xml/builder.rb, line 320 def [] ns @ns = @parent.namespace_definitions.find { |x| x.prefix == ns.to_s } return self if @ns @parent.ancestors.each do |a| next if a == doc @ns = a.namespace_definitions.find { |x| x.prefix == ns.to_s } return self if @ns end raise ArgumentError, "Namespace #{ns} has not been defined" end
cdata(string) Show Source

Create a CDATA Node with content of string

# File lib/nokogiri/xml/builder.rb, line 307 def cdata string insert doc.create_cdata(string) end
comment(string) Show Source

Create a Comment Node with content of string

# File lib/nokogiri/xml/builder.rb, line 313 def comment string insert doc.create_comment(string) end
text(string) Show Source

Create a Text Node with content of string

# File lib/nokogiri/xml/builder.rb, line 301 def text string insert @doc.create_text_node(string) end
to_xml(*args) Show Source

Convert this Builder object to XML

# File lib/nokogiri/xml/builder.rb, line 335 def to_xml(*args) if Nokogiri.jruby? options = args.first.is_a?(Hash) ? args.shift : {} if !options[:save_with] options[:save_with] = Node::SaveOptions::AS_BUILDER end args.insert(0, options) end @doc.to_xml(*args) end