method

to_xml

v3.0.0 - Show latest stable - 1 note - Class: Hash

to_xml(options = {}) public

Returns a string containing an XML representation of its receiver:

  {"foo" => 1, "bar" => 2}.to_xml
  # =>
  # <?xml version="1.0" encoding="UTF-8"?>
  # <hash>
  #   <foo type="integer">1</foo>
  #   <bar type="integer">2</bar>
  # </hash>

To do so, the method loops over the pairs and builds nodes that depend on the values. Given a pair key, value:

If value is a hash there’s a recursive call with key as :root.
If value is an array there’s a recursive call with key as :root, and key singularized as :children.
If value is a callable object it must expect one or two arguments. Depending on the arity, the callable is invoked with the options hash as first argument with key as :root, and key singularized as second argument. Its return value becomes a new node.
If value responds to to_xml the method is invoked with key as :root.

Otherwise, a node with key as tag is created with a string representation of value as text node. If value is nil an attribute "nil" set to "true" is added. Unless the option :skip_types exists and is true, an attribute "type" is added as well according to the following mapping:

  XML_TYPE_NAMES = {
    "Symbol"     => "symbol",
    "Fixnum"     => "integer",
    "Bignum"     => "integer",
    "BigDecimal" => "decimal",
    "Float"      => "float",
    "TrueClass"  => "boolean",
    "FalseClass" => "boolean",
    "Date"       => "date",
    "DateTime"   => "datetime",
    "Time"       => "datetime"
  }

By default the root node is "hash", but that’s configurable via the :root option.

The default XML builder is a fresh instance of Builder::XmlMarkup. You can configure your own builder with the :builder option. The method also accepts options like :dasherize and friends, they are forwarded to the builder.

Show source

# File activesupport/lib/active_support/core_ext/hash/conversions.rb, line 57
  def to_xml(options = {})
    require 'active_support/builder' unless defined?(Builder)

    options = options.dup
    options[:indent]  ||= 2
    options[:root]    ||= "hash"
    options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])

    builder = options[:builder]
    builder.instruct! unless options.delete(:skip_instruct)

    root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options)

    builder.__send__(:method_missing, root) do
      each { |key, value| ActiveSupport::XmlMini.to_tag(key, value, options) }
      yield builder if block_given?
    end
  end

September 13, 2011

0 thanks

more options

useful options are:

:root => ‘object’, :skip_instruct => true, :indent => 2

:builder can also be used to pass your own Builder::XmlMarkup instance.

to_xml

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