Refactored ActiveRecord::Base.to_xml to become a delegate for XmlSerializer, which restores sanity to the mega method. This refactoring also reinstates the opinions that type="string" is redundant and ugly and nil-differentiation is not a concern of serialization [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4431 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 310 insertions, 264 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 6cd4b506da..c90e4d2162 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1664,269 +1664,6 @@ module ActiveRecord #:nodoc:
         @readonly = true
       end
 
-      # Builds an XML document to represent the model.   Some configuration is
-      # availble through +options+, however more complicated cases should use 
-      # override ActiveRecord's to_xml.
-      #
-      # By default the generated XML document will include the processing 
-      # instruction and all object's attributes.  For example:
-      #    
-      #   <?xml version="1.0" encoding="UTF-8"?>
-      #   <topic>
-      #     <title>The First Topic</title>
-      #     <author-name>David</author-name>
-      #     <id type="integer">1</id>
-      #     <approved type="boolean">false</approved>
-      #     <replies-count type="integer">0</replies-count>
-      #     <bonus-time type="datetime">2000-01-01T08:28:00+12:00</bonus-time>
-      #     <written-on type="datetime">2003-07-16T09:28:00+1200</written-on>
-      #     <content>Have a nice day</content>
-      #     <author-email-address>david@loudthinking.com</author-email-address>
-      #     <parent-id></parent-id>
-      #     <last-read type="date">2004-04-15</last-read>
-      #   </topic>
-      #
-      # This behavior can be controlled with :only, :except,
-      # :skip_instruct, :skip_types and :dasherize.  The :only and
-      # :except options are the same as for the #attributes method.
-      # The default is to dasherize all column names, to disable this,
-      # set :dasherize to false.  To not have the column type included
-      # in the XML output, set :skip_types to false.
-      #
-      # For instance:
-      #
-      #   topic.to_xml(:skip_instruct => true, :except => [ :id, :bonus_time, :written_on, :replies_count ])
-      #
-      #   <topic>
-      #     <title>The First Topic</title>
-      #     <author-name>David</author-name>
-      #     <approved type="boolean">false</approved>
-      #     <content>Have a nice day</content>
-      #     <author-email-address>david@loudthinking.com</author-email-address>
-      #     <parent-id></parent-id>
-      #     <last-read type="date">2004-04-15</last-read>
-      #   </topic>
-      # 
-      # To include first level associations use :include
-      #
-      #   firm.to_xml :include => [ :account, :clients ]
-      #
-      #   <?xml version="1.0" encoding="UTF-8"?>
-      #   <firm>
-      #     <id type="integer">1</id>
-      #     <rating type="integer">1</rating>
-      #     <name>37signals</name>
-      #     <clients>
-      #       <client>
-      #         <rating type="integer">1</rating>
-      #         <name>Summit</name>
-      #       </client>
-      #       <client>
-      #         <rating type="integer">1</rating>
-      #         <name>Microsoft</name>
-      #       </client>
-      #     </clients>
-      #     <account>
-      #       <id type="integer">1</id>
-      #       <credit-limit type="integer">50</credit-limit>
-      #     </account>
-      #   </firm>
-      #
-      # To include any methods on the object(s) being called use :methods
-      #
-      #   firm.to_xml :methods => [ :calculated_earnings, :real_earnings ]
-      #
-      #   <firm>
-      #     # ... normal attributes as shown above ...
-      #     <calculated-earnings>100000000000000000</calculated-earnings>
-      #     <real-earnings>5</real-earnings>
-      #   </firm>
-      #
-      # To call any Proc's on the object(s) use :procs.  The Proc's
-      # are passed a modified version of the options hash that was
-      # given to #to_xml.
-      #
-      #   proc = Proc.new { |options| options[:builder].tag!('abc', 'def') }
-      #   firm.to_xml :procs => [ proc ]
-      #
-      #   <firm>
-      #     # ... normal attributes as shown above ...
-      #     <abc>def</abc>
-      #   </firm>
-      #
-      # You may override the to_xml method in your ActiveRecord::Base
-      # subclasses if you need to.  The general form of doing this is
-      #
-      #   class IHaveMyOwnXML < ActiveRecord::Base
-      #     def to_xml(options = {})
-      #       options[:indent] ||= 2
-      #       xml = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
-      #       xml.instruct! unless options[:skip_instruct]
-      #       xml.level_one do
-      #         xml.tag!(:second_level, 'content')
-      #       end
-      #     end
-      #   end
-      def to_xml(options = {})
-        options[:indent] ||= 2
-        builder = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
-
-        unless options[:skip_instruct]
-          builder.instruct!
-          options[:skip_instruct] = true
-        end
-
-        root = (options[:root] || self.class.to_s.underscore).to_s
-        if dasherize = !options.has_key?(:dasherize) || options[:dasherize]
-          root = root.dasherize
-        end
-
-        builder.tag!(root) do
-          # To replicate the behavior in ActiveRecord#attributes,
-          # :except takes precedence over :only.  If :only is not set
-          # for a N level model but is set for the N+1 level models,
-          # then because :except is set to a default value, the second
-          # level model can have both :except and :only set.  So if
-          # :only is set, always delete :except.
-
-          a_names = self.attribute_names
-          if options[:only]
-            options.delete(:except)
-            a_names = a_names & Array(options[:only]).collect { |n| n.to_s }
-          else
-            options[:except] = Array(options[:except]) | Array(self.class.inheritance_column)
-            a_names = a_names - options[:except].collect { |n| n.to_s }
-          end
-
-          columns_hash = self.class.columns_hash
-          a_names.each do |name|
-
-            # To be consistent with the ActiveRecord instance being
-            # converted into a Hash using #attributes, convert SQL
-            # type names.  Map the different "string" types all to
-            # "string", as the client of the XML does not care if a
-            # TEXT or VARCHAR column stores the value.
-
-            type = columns_hash[name].type
-            case type
-            when :text
-              type = :string
-            when :time
-              type = :datetime
-            end
-
-            attributes = options[:skip_types] ? { } : { :type => type }
-
-            value = self.send(name)
-            if dasherize
-              name = name.dasherize
-            end
-
-            # There is a significant speed improvement if the value
-            # does not need to be escaped, as #tag! escapes all values
-            # to ensure that valid XML is generated.  For known binary
-            # values, it is at least an order of magnitude faster to
-            # Base64 encode binary values and directly put them in the
-            # output XML than to pass the original value or the Base64
-            # encoded value to the #tag! method. It definitely makes
-            # no sense to Base64 encode the value and then give it to
-            # #tag!, since that just adds additional overhead.
-            if value.nil?
-              attributes[:nil] = 'true'
-              builder.tag!(name, attributes)
-            else
-              value_needs_no_encoding = false
-              case type
-              when :binary
-                value = Base64.encode64(value)
-                attributes[:encoding] = 'base64'
-                value_needs_no_encoding = true
-              when :date
-                value = value.to_s(:db)
-                value_needs_no_encoding = true
-              when :datetime
-                value = value.xmlschema
-                value_needs_no_encoding = true
-              when :boolean, :float, :integer
-                value = value.to_s
-                value_needs_no_encoding = true
-              end
-
-              if value_needs_no_encoding
-                builder.tag!(name, attributes) do
-                  builder << value
-                end
-              else
-                builder.tag!(name, value, attributes)
-              end
-            end
-          end
-
-          if methods_to_call = options.delete(:methods)
-            [ *methods_to_call ].each do |meth|
-              value = self.send(meth)
-
-              tag = dasherize ? meth.to_s.dasherize : meth.to_s
-
-              type_name = ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[value.class]
-
-              if formatter = ActiveSupport::CoreExtensions::Hash::Conversions::XML_FORMATTING[type_name]
-                value = formatter.call(value)
-              end
-
-              if value.nil?
-                attributes = { :nil => true }
-              else
-                if !options[:skip_types] && !type_name.nil?
-                  attributes = { :type => type_name }
-                else
-                  attributes = { }
-                end
-              end
-
-              builder.tag!(tag, value, attributes)
-            end
-          end
-
-          if include_associations = options.delete(:include)
-            root_only_or_except = { :except => options[:except],
-                                    :only => options[:only] }
-
-            include_has_options = include_associations.is_a?(Hash)
-
-            for association in include_has_options ? include_associations.keys : Array(include_associations)
-              association_options = include_has_options ? include_associations[association] : root_only_or_except
-
-              opts = options.merge(association_options)
-
-              case self.class.reflect_on_association(association).macro
-              when :has_many, :has_and_belongs_to_many
-                records = send(association).to_a
-                unless records.empty?
-                  tag = records.first.class.to_s.underscore.pluralize
-                  if dasherize
-                    tag = tag.dasherize
-                  end
-                  builder.tag!(tag) do
-                    records.each { |r| r.to_xml(opts) }
-                  end
-                end
-              when :has_one, :belongs_to
-                if record = send(association)
-                  record.to_xml(opts.merge(:root => association))
-                end
-              end
-            end
-          end
-
-          if procs = options.delete(:procs)
-            [ *procs ].each do |proc|
-              proc.call(options)
-            end
-          end
-
-        end
-      end
 
     private
       def create_or_update
@@ -2285,4 +2022,4 @@ module ActiveRecord #:nodoc:
         value
       end
   end
-end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record/xml_serialization.rb b/activerecord/lib/active_record/xml_serialization.rb
new file mode 100644
index 0000000000..c8a4e2526c
--- /dev/null
+++ b/activerecord/lib/active_record/xml_serialization.rb
@@ -0,0 +1,309 @@
+module ActiveRecord #:nodoc:
+  module XmlSerialization
+    # Builds an XML document to represent the model.   Some configuration is
+    # availble through +options+, however more complicated cases should use 
+    # override ActiveRecord's to_xml.
+    #
+    # By default the generated XML document will include the processing 
+    # instruction and all object's attributes.  For example:
+    #    
+    #   <?xml version="1.0" encoding="UTF-8"?>
+    #   <topic>
+    #     <title>The First Topic</title>
+    #     <author-name>David</author-name>
+    #     <id type="integer">1</id>
+    #     <approved type="boolean">false</approved>
+    #     <replies-count type="integer">0</replies-count>
+    #     <bonus-time type="datetime">2000-01-01T08:28:00+12:00</bonus-time>
+    #     <written-on type="datetime">2003-07-16T09:28:00+1200</written-on>
+    #     <content>Have a nice day</content>
+    #     <author-email-address>david@loudthinking.com</author-email-address>
+    #     <parent-id></parent-id>
+    #     <last-read type="date">2004-04-15</last-read>
+    #   </topic>
+    #
+    # This behavior can be controlled with :only, :except,
+    # :skip_instruct, :skip_types and :dasherize.  The :only and
+    # :except options are the same as for the #attributes method.
+    # The default is to dasherize all column names, to disable this,
+    # set :dasherize to false.  To not have the column type included
+    # in the XML output, set :skip_types to false.
+    #
+    # For instance:
+    #
+    #   topic.to_xml(:skip_instruct => true, :except => [ :id, :bonus_time, :written_on, :replies_count ])
+    #
+    #   <topic>
+    #     <title>The First Topic</title>
+    #     <author-name>David</author-name>
+    #     <approved type="boolean">false</approved>
+    #     <content>Have a nice day</content>
+    #     <author-email-address>david@loudthinking.com</author-email-address>
+    #     <parent-id></parent-id>
+    #     <last-read type="date">2004-04-15</last-read>
+    #   </topic>
+    # 
+    # To include first level associations use :include
+    #
+    #   firm.to_xml :include => [ :account, :clients ]
+    #
+    #   <?xml version="1.0" encoding="UTF-8"?>
+    #   <firm>
+    #     <id type="integer">1</id>
+    #     <rating type="integer">1</rating>
+    #     <name>37signals</name>
+    #     <clients>
+    #       <client>
+    #         <rating type="integer">1</rating>
+    #         <name>Summit</name>
+    #       </client>
+    #       <client>
+    #         <rating type="integer">1</rating>
+    #         <name>Microsoft</name>
+    #       </client>
+    #     </clients>
+    #     <account>
+    #       <id type="integer">1</id>
+    #       <credit-limit type="integer">50</credit-limit>
+    #     </account>
+    #   </firm>
+    #
+    # To include any methods on the object(s) being called use :methods
+    #
+    #   firm.to_xml :methods => [ :calculated_earnings, :real_earnings ]
+    #
+    #   <firm>
+    #     # ... normal attributes as shown above ...
+    #     <calculated-earnings>100000000000000000</calculated-earnings>
+    #     <real-earnings>5</real-earnings>
+    #   </firm>
+    #
+    # To call any Proc's on the object(s) use :procs.  The Proc's
+    # are passed a modified version of the options hash that was
+    # given to #to_xml.
+    #
+    #   proc = Proc.new { |options| options[:builder].tag!('abc', 'def') }
+    #   firm.to_xml :procs => [ proc ]
+    #
+    #   <firm>
+    #     # ... normal attributes as shown above ...
+    #     <abc>def</abc>
+    #   </firm>
+    #
+    # You may override the to_xml method in your ActiveRecord::Base
+    # subclasses if you need to.  The general form of doing this is
+    #
+    #   class IHaveMyOwnXML < ActiveRecord::Base
+    #     def to_xml(options = {})
+    #       options[:indent] ||= 2
+    #       xml = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
+    #       xml.instruct! unless options[:skip_instruct]
+    #       xml.level_one do
+    #         xml.tag!(:second_level, 'content')
+    #       end
+    #     end
+    #   end
+    def to_xml(options = {})
+      XmlSerializer.new(self, options).to_s
+    end
+  end
+
+  class XmlSerializer #:nodoc:
+    attr_reader :options
+    
+    def initialize(record, options = {})
+      @record, @options = record, options
+    end
+    
+    def builder
+      @builder ||= begin
+        options[:indent] ||= 2
+        builder = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
+
+        unless options[:skip_instruct]
+          builder.instruct!
+          options[:skip_instruct] = true
+        end
+        
+        builder
+      end
+    end
+
+    def root
+      root = (options[:root] || @record.class.to_s.underscore).to_s
+      dasherize? ? root.dasherize : root
+    end
+    
+    def dasherize?
+      !options.has_key?(:dasherize) || options[:dasherize]
+    end
+
+
+    # To replicate the behavior in ActiveRecord#attributes,
+    # :except takes precedence over :only.  If :only is not set
+    # for a N level model but is set for the N+1 level models,
+    # then because :except is set to a default value, the second
+    # level model can have both :except and :only set.  So if
+    # :only is set, always delete :except.
+    def serializable_attributes
+      attribute_names = @record.attribute_names
+
+      if options[:only]
+        options.delete(:except)
+        attribute_names = attribute_names & Array(options[:only]).collect { |n| n.to_s }
+      else
+        options[:except] = Array(options[:except]) | Array(@record.class.inheritance_column)
+        attribute_names = attribute_names - options[:except].collect { |n| n.to_s }
+      end
+      
+      attribute_names.collect { |name| Attribute.new(name, @record) }
+    end
+
+    def serializable_method_attributes
+      Array(options.delete(:methods)).collect { |name| MethodAttribute.new(name.to_s, @record) }
+    end
+
+
+    def add_attributes
+      (serializable_attributes + serializable_method_attributes).each do |attribute|
+        add_tag(attribute)
+      end
+    end
+
+    def add_includes
+      if include_associations = options.delete(:include)
+        root_only_or_except = { :except => options[:except],
+                                :only => options[:only] }
+
+        include_has_options = include_associations.is_a?(Hash)
+
+        for association in include_has_options ? include_associations.keys : Array(include_associations)
+          association_options = include_has_options ? include_associations[association] : root_only_or_except
+
+          opts = options.merge(association_options)
+
+          case @record.class.reflect_on_association(association).macro
+          when :has_many, :has_and_belongs_to_many
+            records = @record.send(association).to_a
+            unless records.empty?
+              tag = records.first.class.to_s.underscore.pluralize
+              tag = tag.dasherize if dasherize?
+
+              builder.tag!(tag) do
+                records.each { |r| r.to_xml(opts) }
+              end
+            end
+          when :has_one, :belongs_to
+            if record = @record.send(association)
+              record.to_xml(opts.merge(:root => association))
+            end
+          end
+        end
+      end
+    end
+
+    def add_procs
+      if procs = options.delete(:procs)
+        [ *procs ].each do |proc|
+          proc.call(options)
+        end
+      end
+    end
+
+
+    def add_tag(attribute)
+      if attribute.needs_encoding?
+        builder.tag!(
+          dasherize? ? attribute.name.dasherize : attribute.name, 
+          attribute.value.to_s, 
+          attribute.decorations(!options[:skip_types])
+        )
+      else
+        builder.tag!(
+          dasherize? ? attribute.name.dasherize : attribute.name, 
+          attribute.decorations(!options[:skip_types])) do
+          builder << attribute.value.to_s
+        end
+      end
+    end
+
+    def serialize
+      builder.tag!(root) do
+        add_attributes
+        add_includes
+        add_procs
+      end
+    end
+    
+    alias_method :to_s, :serialize
+
+    class Attribute #:nodoc:
+      attr_reader :name, :value, :type
+    
+      def initialize(name, record)
+        @name, @record = name, record
+      
+        @type  = compute_type
+        @value = compute_value
+      end
+
+      # There is a significant speed improvement if the value
+      # does not need to be escaped, as #tag! escapes all values
+      # to ensure that valid XML is generated.  For known binary
+      # values, it is at least an order of magnitude faster to
+      # Base64 encode binary values and directly put them in the
+      # output XML than to pass the original value or the Base64
+      # encoded value to the #tag! method. It definitely makes
+      # no sense to Base64 encode the value and then give it to
+      # #tag!, since that just adds additional overhead.
+      def needs_encoding?
+        ![ :binary, :date, :datetime, :boolean, :float, :integer ].include?(type)
+      end
+    
+      def decorations(include_types = true)
+        decorations = {}
+
+        if type == :binary
+          decorations[:encoding] = 'base64'
+        end
+      
+        if include_types && type != :string
+          decorations[:type] = type
+        end
+      
+        decorations
+      end
+    
+      protected
+        def compute_type
+          type = @record.class.columns_hash[name].type
+
+          case type
+            when :text
+              :string
+            when :time
+              :datetime
+            else
+              type
+          end
+        end
+    
+        def compute_value
+          value = @record.send(name)
+        
+          if formatter = Hash::XML_FORMATTING[type.to_s]
+            value ? formatter.call(value) : nil
+          else
+            value
+          end
+        end
+    end
+  
+    class MethodAttribute < Attribute #:nodoc:
+      protected
+        def compute_type
+          Hash::XML_TYPE_NAMES[@record.send(name).class] || :string
+        end
+    end
+  end
+end
\ No newline at end of file