vendor/rails/activerecord/lib/active_record/serializers/xml_serializer.rb

   1 module ActiveRecord #:nodoc:
   2   module Serialization
   3     # Builds an XML document to represent the model. Some configuration is
   4     # available through +options+. However more complicated cases should
   5     # override ActiveRecord::Base#to_xml.
   6     #
   7     # By default the generated XML document will include the processing
   8     # instruction and all the object's attributes. For example:
   9     #
  10     #   <?xml version="1.0" encoding="UTF-8"?>
  11     #   <topic>
  12     #     <title>The First Topic</title>
  13     #     <author-name>David</author-name>
  14     #     <id type="integer">1</id>
  15     #     <approved type="boolean">false</approved>
  16     #     <replies-count type="integer">0</replies-count>
  17     #     <bonus-time type="datetime">2000-01-01T08:28:00+12:00</bonus-time>
  18     #     <written-on type="datetime">2003-07-16T09:28:00+1200</written-on>
  19     #     <content>Have a nice day</content>
  20     #     <author-email-address>david@loudthinking.com</author-email-address>
  21     #     <parent-id></parent-id>
  22     #     <last-read type="date">2004-04-15</last-read>
  23     #   </topic>
  24     #
  25     # This behavior can be controlled with <tt>:only</tt>, <tt>:except</tt>,
  26     # <tt>:skip_instruct</tt>, <tt>:skip_types</tt> and <tt>:dasherize</tt>.
  27     # The <tt>:only</tt> and <tt>:except</tt> options are the same as for the
  28     # +attributes+ method. The default is to dasherize all column names, but you
  29     # can disable this setting <tt>:dasherize</tt> to +false+. To not have the
  30     # column type included in the XML output set <tt>:skip_types</tt> to +true+.
  31     #
  32     # For instance:
  33     #
  34     #   topic.to_xml(:skip_instruct => true, :except => [ :id, :bonus_time, :written_on, :replies_count ])
  35     #
  36     #   <topic>
  37     #     <title>The First Topic</title>
  38     #     <author-name>David</author-name>
  39     #     <approved type="boolean">false</approved>
  40     #     <content>Have a nice day</content>
  41     #     <author-email-address>david@loudthinking.com</author-email-address>
  42     #     <parent-id></parent-id>
  43     #     <last-read type="date">2004-04-15</last-read>
  44     #   </topic>
  45     #
  46     # To include first level associations use <tt>:include</tt>:
  47     #
  48     #   firm.to_xml :include => [ :account, :clients ]
  49     #
  50     #   <?xml version="1.0" encoding="UTF-8"?>
  51     #   <firm>
  52     #     <id type="integer">1</id>
  53     #     <rating type="integer">1</rating>
  54     #     <name>37signals</name>
  55     #     <clients type="array">
  56     #       <client>
  57     #         <rating type="integer">1</rating>
  58     #         <name>Summit</name>
  59     #       </client>
  60     #       <client>
  61     #         <rating type="integer">1</rating>
  62     #         <name>Microsoft</name>
  63     #       </client>
  64     #     </clients>
  65     #     <account>
  66     #       <id type="integer">1</id>
  67     #       <credit-limit type="integer">50</credit-limit>
  68     #     </account>
  69     #   </firm>
  70     #
  71     # To include deeper levels of associations pass a hash like this:
  72     #
  73     #   firm.to_xml :include => {:account => {}, :clients => {:include => :address}}
  74     #   <?xml version="1.0" encoding="UTF-8"?>
  75     #   <firm>
  76     #     <id type="integer">1</id>
  77     #     <rating type="integer">1</rating>
  78     #     <name>37signals</name>
  79     #     <clients type="array">
  80     #       <client>
  81     #         <rating type="integer">1</rating>
  82     #         <name>Summit</name>
  83     #         <address>
  84     #           ...
  85     #         </address>
  86     #       </client>
  87     #       <client>
  88     #         <rating type="integer">1</rating>
  89     #         <name>Microsoft</name>
  90     #         <address>
  91     #           ...
  92     #         </address>
  93     #       </client>
  94     #     </clients>
  95     #     <account>
  96     #       <id type="integer">1</id>
  97     #       <credit-limit type="integer">50</credit-limit>
  98     #     </account>
  99     #   </firm>
 100     #
 101     # To include any methods on the model being called use <tt>:methods</tt>:
 102     #
 103     #   firm.to_xml :methods => [ :calculated_earnings, :real_earnings ]
 104     #
 105     #   <firm>
 106     #     # ... normal attributes as shown above ...
 107     #     <calculated-earnings>100000000000000000</calculated-earnings>
 108     #     <real-earnings>5</real-earnings>
 109     #   </firm>
 110     #
 111     # To call any additional Procs use <tt>:procs</tt>. The Procs are passed a
 112     # modified version of the options hash that was given to +to_xml+:
 113     #
 114     #   proc = Proc.new { |options| options[:builder].tag!('abc', 'def') }
 115     #   firm.to_xml :procs => [ proc ]
 116     #
 117     #   <firm>
 118     #     # ... normal attributes as shown above ...
 119     #     <abc>def</abc>
 120     #   </firm>
 121     #
 122     # Alternatively, you can yield the builder object as part of the +to_xml+ call:
 123     #
 124     #   firm.to_xml do |xml|
 125     #     xml.creator do
 126     #       xml.first_name "David"
 127     #       xml.last_name "Heinemeier Hansson"
 128     #     end
 129     #   end
 130     #
 131     #   <firm>
 132     #     # ... normal attributes as shown above ...
 133     #     <creator>
 134     #       <first_name>David</first_name>
 135     #       <last_name>Heinemeier Hansson</last_name>
 136     #     </creator>
 137     #   </firm>
 138     #
 139     # As noted above, you may override +to_xml+ in your ActiveRecord::Base
 140     # subclasses to have complete control about what's generated. The general
 141     # form of doing this is:
 142     #
 143     #   class IHaveMyOwnXML < ActiveRecord::Base
 144     #     def to_xml(options = {})
 145     #       options[:indent] ||= 2
 146     #       xml = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
 147     #       xml.instruct! unless options[:skip_instruct]
 148     #       xml.level_one do
 149     #         xml.tag!(:second_level, 'content')
 150     #       end
 151     #     end
 152     #   end
 153     def to_xml(options = {}, &block)
 154       serializer = XmlSerializer.new(self, options)
 155       block_given? ? serializer.to_s(&block) : serializer.to_s
 156     end
 157
 158     def from_xml(xml)
 159       self.attributes = Hash.from_xml(xml).values.first
 160       self
 161     end
 162   end
 163
 164   class XmlSerializer < ActiveRecord::Serialization::Serializer #:nodoc:
 165     def builder
 166       @builder ||= begin
 167         options[:indent] ||= 2
 168         builder = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
 169
 170         unless options[:skip_instruct]
 171           builder.instruct!
 172           options[:skip_instruct] = true
 173         end
 174
 175         builder
 176       end
 177     end
 178
 179     def root
 180       root = (options[:root] || @record.class.to_s.underscore).to_s
 181       dasherize? ? root.dasherize : root
 182     end
 183
 184     def dasherize?
 185       !options.has_key?(:dasherize) || options[:dasherize]
 186     end
 187
 188     def serializable_attributes
 189       serializable_attribute_names.collect { |name| Attribute.new(name, @record) }
 190     end
 191
 192     def serializable_method_attributes
 193       Array(options[:methods]).inject([]) do |method_attributes, name|
 194         method_attributes << MethodAttribute.new(name.to_s, @record) if @record.respond_to?(name.to_s)
 195         method_attributes
 196       end
 197     end
 198
 199     def add_attributes
 200       (serializable_attributes + serializable_method_attributes).each do |attribute|
 201         add_tag(attribute)
 202       end
 203     end
 204
 205     def add_procs
 206       if procs = options.delete(:procs)
 207         [ *procs ].each do |proc|
 208           proc.call(options)
 209         end
 210       end
 211     end
 212
 213     def add_tag(attribute)
 214       builder.tag!(
 215         dasherize? ? attribute.name.dasherize : attribute.name,
 216         attribute.value.to_s,
 217         attribute.decorations(!options[:skip_types])
 218       )
 219     end
 220
 221     def add_associations(association, records, opts)
 222       if records.is_a?(Enumerable)
 223         tag = association.to_s
 224         tag = tag.dasherize if dasherize?
 225         if records.empty?
 226           builder.tag!(tag, :type => :array)
 227         else
 228           builder.tag!(tag, :type => :array) do
 229             association_name = association.to_s.singularize
 230             records.each do |record|
 231               record.to_xml opts.merge(
 232                 :root => association_name,
 233                 :type => (record.class.to_s.underscore == association_name ? nil : record.class.name)
 234               )
 235             end
 236           end
 237         end
 238       else
 239         if record = @record.send(association)
 240           record.to_xml(opts.merge(:root => association))
 241         end
 242       end
 243     end
 244
 245     def serialize
 246       args = [root]
 247       if options[:namespace]
 248         args << {:xmlns=>options[:namespace]}
 249       end
 250
 251       if options[:type]
 252         args << {:type=>options[:type]}
 253       end
 254
 255       builder.tag!(*args) do
 256         add_attributes
 257         procs = options.delete(:procs)
 258         add_includes { |association, records, opts| add_associations(association, records, opts) }
 259         options[:procs] = procs
 260         add_procs
 261         yield builder if block_given?
 262       end
 263     end
 264
 265     class Attribute #:nodoc:
 266       attr_reader :name, :value, :type
 267
 268       def initialize(name, record)
 269         @name, @record = name, record
 270
 271         @type  = compute_type
 272         @value = compute_value
 273       end
 274
 275       # There is a significant speed improvement if the value
 276       # does not need to be escaped, as <tt>tag!</tt> escapes all values
 277       # to ensure that valid XML is generated. For known binary
 278       # values, it is at least an order of magnitude faster to
 279       # Base64 encode binary values and directly put them in the
 280       # output XML than to pass the original value or the Base64
 281       # encoded value to the <tt>tag!</tt> method. It definitely makes
 282       # no sense to Base64 encode the value and then give it to
 283       # <tt>tag!</tt>, since that just adds additional overhead.
 284       def needs_encoding?
 285         ![ :binary, :date, :datetime, :boolean, :float, :integer ].include?(type)
 286       end
 287
 288       def decorations(include_types = true)
 289         decorations = {}
 290
 291         if type == :binary
 292           decorations[:encoding] = 'base64'
 293         end
 294
 295         if include_types && type != :string
 296           decorations[:type] = type
 297         end
 298
 299         if value.nil?
 300           decorations[:nil] = true
 301         end
 302
 303         decorations
 304       end
 305
 306       protected
 307         def compute_type
 308           type = @record.class.serialized_attributes.has_key?(name) ? :yaml : @record.class.columns_hash[name].type
 309
 310           case type
 311             when :text
 312               :string
 313             when :time
 314               :datetime
 315             else
 316               type
 317           end
 318         end
 319
 320         def compute_value
 321           value = @record.send(name)
 322
 323           if formatter = Hash::XML_FORMATTING[type.to_s]
 324             value ? formatter.call(value) : nil
 325           else
 326             value
 327           end
 328         end
 329     end
 330
 331     class MethodAttribute < Attribute #:nodoc:
 332       protected
 333         def compute_type
 334           Hash::XML_TYPE_NAMES[@record.send(name).class.name] || :string
 335         end
 336     end
 337   end
 338 end