Patch to ActiveModel's (and ActiveRecord, by association) XML serialization:...

Patch to ActiveModel's (and ActiveRecord, by association) XML serialization: If two parameters are present in Procs supplied to to_xml's :procs option, the model being serialized will be passed as the second argument [#2373 state:resolved]
Signed-off-by: NJoshua Peek <josh@joshpeek.com>

activemodel/lib/active_model/serializers/xml.rb

@@ -152,7 +152,11 @@ def add_attributes
           def add_procs
             if procs = options.delete(:procs)
               [ *procs ].each do |proc|
-                proc.call(options)
+                if proc.arity > 1
+                  proc.call(options, @serializable)
+                else
+                  proc.call(options)
+                end
               end
             end
           end

activemodel/test/cases/serializeration/xml_serialization_test.rb

@@ -82,4 +82,16 @@ def setup
   test "should serialize yaml" do
     assert_match %r{<preferences type=\"yaml\">--- \n:gem: ruby\n</preferences>}, @contact.to_xml
   end
+
+  test "should call proc on object" do
+    proc = Proc.new { |options| options[:builder].tag!('nationality', 'unknown') }
+    xml = @contact.to_xml(:procs => [ proc ])
+    assert_match %r{<nationality>unknown</nationality>}, xml
+  end
+
+  test 'should supply serializable to second proc argument' do
+    proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
+    xml = @contact.to_xml(:procs => [ proc ])
+    assert_match %r{<name-reverse>kcats noraa</name-reverse>}, xml
+  end
 end

activerecord/lib/active_record/serializers/xml_serializer.rb

@@ -71,6 +71,21 @@ module Serialization
     #     </account>
     #   </firm>
     #
+    # Additionally, the record being serialized will be passed to a Proc's second
+    # parameter.  This allows for ad hoc additions to the resultant document that
+    # incorporate the context of the record being serialized. And by leveraging the
+    # closure created by a Proc, to_xml can be used to add elements that normally fall
+    # outside of the scope of the model -- for example, generating and appending URLs
+    # associated with models.
+    # 
+    #   proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
+    #   firm.to_xml :procs => [ proc ]
+    #
+    #   <firm>
+    #     # ... normal attributes as shown above ...
+    #     <name-reverse>slangis73</name-reverse>
+    #   </firm>
+    #
     # To include deeper levels of associations pass a hash like this:
     #
     #   firm.to_xml :include => {:account => {}, :clients => {:include => :address}}

activerecord/test/cases/xml_serialization_test.rb

@@ -174,6 +174,12 @@ def test_procs_are_called_on_object
     assert_match %r{<nationality>Danish</nationality>}, xml
   end
 
+  def test_dual_arity_procs_are_called_on_object
+    proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
+    xml = authors(:david).to_xml(:procs => [ proc ])
+    assert_match %r{<name-reverse>divaD</name-reverse>}, xml
+  end
+
   def test_top_level_procs_arent_applied_to_associations
     author_proc = Proc.new { |options| options[:builder].tag!('nationality', 'Danish') }
     xml = authors(:david).to_xml(:procs => [ author_proc ], :include => :posts, :indent => 2)