From 35c058e156a2a43775211cf1d992bd25b8256283 Mon Sep 17 00:00:00 2001
From: Emmanuel Nicolau <emma@ketsui.com.ar>
Date: Wed, 26 Nov 2008 11:31:08 -0200
Subject: [PATCH] XmlSerializer with skip_nils option

---
 .../active_record/serializers/xml_serializer.rb    |    8 +++++---
 activerecord/test/cases/xml_serialization_test.rb  |   14 ++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/serializers/xml_serializer.rb b/activerecord/lib/active_record/serializers/xml_serializer.rb
index d171b74..e6202cc 100644
--- a/activerecord/lib/active_record/serializers/xml_serializer.rb
+++ b/activerecord/lib/active_record/serializers/xml_serializer.rb
@@ -23,12 +23,14 @@ module ActiveRecord #:nodoc:
     #   </topic>
     #
     # This behavior can be controlled with <tt>:only</tt>, <tt>:except</tt>,
-    # <tt>:skip_instruct</tt>, <tt>:skip_types</tt> and <tt>:dasherize</tt>.
+    # <tt>:skip_instruct</tt>, <tt>:skip_types</tt>, <tt>:skip_nils</tt> and <tt>:dasherize</tt>.
     # The <tt>:only</tt> and <tt>:except</tt> options are the same as for the
     # +attributes+ method. The default is to dasherize all column names, but you
     # can disable this setting <tt>:dasherize</tt> to +false+. To not have the
     # column type included in the XML output set <tt>:skip_types</tt> to +true+.
-    #
+    # If you don't want to have the xml element for a nil column present in the
+    # output, set <tt>:skip_nils</tt> to +true+.
+    # 
     # For instance:
     #
     #   topic.to_xml(:skip_instruct => true, :except => [ :id, :bonus_time, :written_on, :replies_count ])
@@ -215,7 +217,7 @@ module ActiveRecord #:nodoc:
         dasherize? ? attribute.name.dasherize : attribute.name,
         attribute.value.to_s,
         attribute.decorations(!options[:skip_types])
-      )
+      ) unless options[:skip_nils] && attribute.value.nil?
     end
 
     def add_associations(association, records, opts)
diff --git a/activerecord/test/cases/xml_serialization_test.rb b/activerecord/test/cases/xml_serialization_test.rb
index 63f4886..b422393 100644
--- a/activerecord/test/cases/xml_serialization_test.rb
+++ b/activerecord/test/cases/xml_serialization_test.rb
@@ -115,6 +115,20 @@ class NilXmlSerializationTest < ActiveRecord::TestCase
     attributes = $1
     assert_match %r{type="yaml"}, attributes
     assert_match %r{nil="true"}, attributes
+  end  
+end
+
+class NilXmlSerializationWithOptionSkipNilTest < ActiveRecord::TestCase
+  def setup
+    @xml = Contact.new.to_xml(:skip_nils => true)
+  end
+
+  def test_should_not_serialize_string
+    assert !%r{<name.*></name>}.match(@xml)
+  end
+
+  def test_should_not_serialize_integer
+    assert !%r{<age.*></age>}.match(@xml)
   end
 end
 
-- 
1.6.0.1