class Nokogiri::XML::Builder

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.

`Namespace` inheritance¶ ↑

In the Builder context, children will inherit their parent’s namespace. This is the same behavior as if the underlying {XML::Document} set namespace_inheritance to true:

result = Nokogiri::XML::Builder.new do |xml|
  xml["soapenv"].Envelope("xmlns:soapenv" => "http://schemas.xmlsoap.org/soap/envelope/") do
    xml.Header
  end
end
result.doc.to_xml
# => <?xml version="1.0" encoding="utf-8"?>
#    <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
#      <soapenv:Header/>
#    </soapenv:Envelope>

Users may turn this behavior off by passing a keyword argument namespace_inheritance:false to the initializer:

result = Nokogiri::XML::Builder.new(namespace_inheritance: false) do |xml|
  xml["soapenv"].Envelope("xmlns:soapenv" => "http://schemas.xmlsoap.org/soap/envelope/") do
    xml.Header
    xml["soapenv"].Body # users may explicitly opt into the namespace
  end
end
result.doc.to_xml
# => <?xml version="1.0" encoding="utf-8"?>
#    <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
#      <Header/>
#      <soapenv:Body/>
#    </soapenv:Envelope>

For more information on namespace inheritance, please see {XML::Document#namespace_inheritance}

`Document` Types¶ ↑

To create a document type (DTD), 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>

Constants

DEFAULT_DOCUMENT_OPTIONS
VALID_NAMESPACES: Included from Nokogiri::ClassResolver

related_class restricts matching namespaces to those matching this set.

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 = {}, root = nil) { |self| ... }

Source

# File lib/nokogiri/xml/builder.rb, line 307
def initialize(options = {}, root = nil, &block)
  if root
    @doc = root.document
    @parent = root
  else
    @parent = @doc = related_class("Document").new
  end

  @context = nil
  @arity = nil
  @ns = nil

  options = DEFAULT_DOCUMENT_OPTIONS.merge(options)
  options.each do |k, v|
    @doc.send(:"#{k}=", v)
  end

  return unless block

  @arity = block.arity
  if @arity <= 0
    @context = eval("self", block.binding)
    instance_eval(&block)
  else
    yield self
  end

  @parent = @doc
end

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

with (root, &block)

Source

# File lib/nokogiri/xml/builder.rb, line 294
def self.with(root, &block)
  new({}, root, &block)
end

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(File.read('somedoc.xml'))
Nokogiri::XML::Builder.with(doc.at_css('some_tag')) do |xml|
  # ... Use normal builder methods here ...
  xml.awesome # add the "awesome" tag below "some_tag"
end

Public Instance Methods

<< (string)

Source

# File lib/nokogiri/xml/builder.rb, line 390
def <<(string)
  @doc.fragment(string).children.each { |x| insert(x) }
end

Append the given raw XML string to the document

[] (ns)

Source

# File lib/nokogiri/xml/builder.rb, line 358
def [](ns)
  if @parent != @doc
    @ns = @parent.namespace_definitions.find { |x| x.prefix == ns.to_s }
  end
  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

  @ns = { pending: ns.to_s }
  self
end

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

cdata (string)

Source

# File lib/nokogiri/xml/builder.rb, line 345
def cdata(string)
  insert(doc.create_cdata(string))
end

Create a CDATA Node with content of string

comment (string)

Source

# File lib/nokogiri/xml/builder.rb, line 351
def comment(string)
  insert(doc.create_comment(string))
end

Create a Comment Node with content of string

related_class(class_name) → Class

Source

# File lib/nokogiri/class_resolver.rb, line 46
def related_class(class_name)
  klass = nil
  inspecting = self.class

  while inspecting
    namespace_path = inspecting.name.split("::")[0..-2]
    inspecting = inspecting.superclass

    next unless VALID_NAMESPACES.include?(namespace_path.last)

    related_class_name = (namespace_path << class_name).join("::")
    klass = begin
      Object.const_get(related_class_name)
    rescue NameError
      nil
    end
    break if klass
  end
  klass
end

Included from Nokogiri::ClassResolver

Find a class constant within the

Some examples:

Nokogiri::XML::Document.new.related_class("DocumentFragment")
# => Nokogiri::XML::DocumentFragment
Nokogiri::HTML4::Document.new.related_class("DocumentFragment")
# => Nokogiri::HTML4::DocumentFragment

Note this will also work for subclasses that follow the same convention, e.g.:

Loofah::HTML::Document.new.related_class("DocumentFragment")
# => Loofah::HTML::DocumentFragment

And even if it’s a subclass, this will iterate through the superclasses:

class ThisIsATopLevelClass < Nokogiri::HTML4::Builder ; end
ThisIsATopLevelClass.new.related_class("Document")
# => Nokogiri::HTML4::Document

text (string)

Source

# File lib/nokogiri/xml/builder.rb, line 339
def text(string)
  insert(@doc.create_text_node(string))
end

Create a Text Node with content of string

to_xml (*args)

Source

# File lib/nokogiri/xml/builder.rb, line 377
def to_xml(*args)
  if Nokogiri.jruby?
    options = args.first.is_a?(Hash) ? args.shift : {}
    unless options[:save_with]
      options[:save_with] = Node::SaveOptions::AS_BUILDER
    end
    args.insert(0, options)
  end
  @doc.to_xml(*args)
end

Convert this Builder object to XML

class Nokogiri::XML::Builder

Synopsis:¶ ↑

Builder scope¶ ↑

Special Tags¶ ↑

Tag Attributes¶ ↑

Tag Attribute Short Cuts¶ ↑

Namespaces¶ ↑

Referencing declared namespaces¶ ↑

Namespace inheritance¶ ↑

Document Types¶ ↑

`Builder` scope¶ ↑

`Namespace` inheritance¶ ↑

`Document` Types¶ ↑