ActiveModel support for the :include serialization option

This commit moves support for the :include serialization option for
serializing associated objects out of ActiveRecord in into ActiveModel.
The following methods support the :include option:

  * serializable_hash
  * to_json
  * to_xml

Instances must respond to methods named by the values of the :includes
array (or keys of the :includes hash). If an association method returns
an object that is_a?(Enumerable) (which AR has_many associations do), it
is assumed to be a collection association, and its elements must respond
to :serializable_hash. Otherwise it must respond to :serializable_hash
itself.

While here, fix #858, XmlSerializer should not singularize already
singular association names.

2 files changed, 1 insertions, 81 deletions

diff --git a/activerecord/lib/active_record/serialization.rb b/activerecord/lib/active_record/serialization.rb
index e3185a9c5a..5ad40d8cd9 100644
--- a/activerecord/lib/active_record/serialization.rb
+++ b/activerecord/lib/active_record/serialization.rb
@@ -10,46 +10,8 @@ module ActiveRecord #:nodoc:
       options[:except] = Array.wrap(options[:except]).map { |n| n.to_s }
       options[:except] |= Array.wrap(self.class.inheritance_column)
 
-      hash = super(options)
-
-      serializable_add_includes(options) do |association, records, opts|
-        hash[association] = records.is_a?(Enumerable) ?
-          records.map { |r| r.serializable_hash(opts) } :
-          records.serializable_hash(opts)
-      end
-
-      hash
+      super(options)
     end
-
-    private
-      # Add associations specified via the <tt>:include</tt> option.
-      #
-      # Expects a block that takes as arguments:
-      #   +association+ - name of the association
-      #   +records+     - the association record(s) to be serialized
-      #   +opts+        - options for the association records
-      def serializable_add_includes(options = {})
-        return unless include_associations = options.delete(:include)
-
-        include_has_options = include_associations.is_a?(Hash)
-        associations = include_has_options ? include_associations.keys : Array.wrap(include_associations)
-
-        associations.each do |association|
-          records = case self.class.reflect_on_association(association).macro
-          when :has_many, :has_and_belongs_to_many
-            send(association).to_a
-          when :has_one, :belongs_to
-            send(association)
-          end
-
-          if records
-            association_options = include_has_options ? include_associations[association] : {}
-            yield(association, records, association_options)
-          end
-        end
-
-        options[:include] = include_associations
-      end
   end
 end
 
diff --git a/activerecord/lib/active_record/serializers/xml_serializer.rb b/activerecord/lib/active_record/serializers/xml_serializer.rb
index 67f6c7833c..cbfa1ad609 100644
--- a/activerecord/lib/active_record/serializers/xml_serializer.rb
+++ b/activerecord/lib/active_record/serializers/xml_serializer.rb
@@ -182,48 +182,6 @@ module ActiveRecord #:nodoc:
       options[:except] |= Array.wrap(@serializable.class.inheritance_column)
     end
 
-    def add_extra_behavior
-      add_includes
-    end
-
-    def add_includes
-      procs = options.delete(:procs)
-      @serializable.send(:serializable_add_includes, options) do |association, records, opts|
-        add_associations(association, records, opts)
-      end
-      options[:procs] = procs
-    end
-
-    # TODO This can likely be cleaned up to simple use ActiveSupport::XmlMini.to_tag as well.
-    def add_associations(association, records, opts)
-      association_name = association.to_s.singularize
-      merged_options   = options.merge(opts).merge!(:root => association_name, :skip_instruct => true)
-
-      if records.is_a?(Enumerable)
-        tag  = ActiveSupport::XmlMini.rename_key(association.to_s, options)
-        type = options[:skip_types] ? { } : {:type => "array"}
-
-        if records.empty?
-          @builder.tag!(tag, type)
-        else
-          @builder.tag!(tag, type) do
-            records.each do |record|
-              if options[:skip_types]
-                record_type = {}
-              else
-                record_class = (record.class.to_s.underscore == association_name) ? nil : record.class.name
-                record_type = {:type => record_class}
-              end
-
-              record.to_xml merged_options.merge(record_type)
-            end
-          end
-        end
-      else
-        records.to_xml(merged_options)
-      end
-    end
-
     class Attribute < ActiveModel::Serializers::Xml::Serializer::Attribute #:nodoc:
       def compute_type
         klass = @serializable.class