Added serialization callbacks.

lib/dm-serializer/common.rb

@@ -22,6 +22,19 @@ def properties_to_serialize(options)
         end
       end
     end
+
+    # add properties as a result from the serialization callback
+    def invoke_serialization_callback
+      serialization_callback_result = {}
+      if respond_to?(:serialization_callback)
+        serialization_callback_result = serialization_callback
+        unless serialization_callback_result.is_a?(Hash)
+          raise "#serialization_callback should return a Hash, found #{serialization_callback_result.class}"
+        end
+      end
+      serialization_callback_result
+    end
+
   end
 
   Model.append_inclusions(Serializer)

lib/dm-serializer/to_csv.rb

@@ -26,6 +26,9 @@ def to_csv(*args)
         row = properties_to_serialize(options).map do |property|
           __send__(property.name).to_s
         end
+        row += invoke_serialization_callback.map do |key, value|
+          value.to_s
+        end
         csv << row
       end
     end

lib/dm-serializer/to_json.rb

@@ -31,6 +31,8 @@ def as_json(options = {})
         result[method] = __send__(method)
       end
 
+      result.merge! invoke_serialization_callback
+
       # Note: if you want to include a whole other model via relation, use
       # :methods:
       #

lib/dm-serializer/to_xml.rb

@@ -59,6 +59,15 @@ def to_xml_document(opts={}, doc = nil)
         end
       end
 
+      invoke_serialization_callback.each do |key, value|
+        xml_key_name = key.to_s.gsub(/[^a-z0-9_]/, '')
+        if value.respond_to?(:to_xml_document)
+          xml.add_xml(root, value.to_xml_document)
+        else
+          xml.add_node(root, xml_key_name, value.to_s)
+        end
+      end
+
       doc
     end
 

lib/dm-serializer/to_yaml.rb

@@ -59,6 +59,10 @@ def encode_with(coder, options = {})
         value = __send__(method)
         coder.add(method, value.is_a?(Class) ? value.to_s : value)
       end
+
+      invoke_serialization_callback.each do |key, value|
+        coder.add(key.to_s, value.is_a?(Class) ? value.to_s : value)
+      end
     end
 
   private

spec/public/to_csv_spec.rb

@@ -64,8 +64,27 @@
           george.to_csv.should match(/false/)
         end
       end
+    end
+  end
+
+  describe DataMapper::Serialize, '#to_csv' do
+
+    it "supports serialization_callbacks" do
+      class Horse
+        include DataMapper::Resource
 
+        property :id, Serial
+        property :name, String
+
+        def serialization_callback
+          { :external_name => "#{name}_external" }
+        end
+      end
+
+      horse = Horse.new(:name => 'legolas')
+      horse.to_csv.should match(/legolas_external/)
     end
+
   end
 else
   warn "[WARNING] Cannot require 'faster_csv' or 'csv', not running #to_csv specs"

spec/public/to_json_spec.rb

@@ -73,3 +73,38 @@ def deserialize(result)
     Motorcycle.new.as_json[:type].should == "Motorcycle"
   end
 end
+
+describe DataMapper::Serializer, '#as_json' do
+  before(:each) do
+    class Horse
+      include DataMapper::Resource
+
+      property :id, Serial
+      property :name, String
+
+      def serialization_callback
+        { :external_name => "#{name}_external" }
+      end
+    end
+  end
+
+  it "supports serialization_callbacks" do
+    horse = Horse.new(:name => 'legolas')
+    horse.as_json[:external_name].should == 'legolas_external'
+  end
+
+  it "should raise an exception when the serialization_callback does not return a Hash" do
+    class Horse
+      def serialization_callback
+        name
+      end
+    end
+
+    expect { Horse.new(:name => 'legolas').as_json }.to raise_error
+  end
+
+  it "should not raise an exception when the serialization_callback returns a Hash" do
+    expect { Horse.new(:name => 'legolas').as_json }.to_not raise_error
+  end
+
+end

spec/public/to_xml_spec.rb

@@ -107,4 +107,23 @@ def cast(value, type)
       end
     end
   end
+
+  describe "adding properties from serialization_callback as well" do
+    it "should call the serialization_callback method and add the results" do
+      class Horse
+        include DataMapper::Resource
+
+        property :id, Serial
+        property :name, String
+
+        def serialization_callback
+          { :external_name => "#{name}_external" }
+        end
+      end
+
+      horse = Horse.create(:name => 'legolas')
+      result = horse.to_xml
+      puts REXML::Document.new(result).elements[1].elements["external_name"].text == 'legolas_external'
+    end
+  end
 end

spec/public/to_yaml_spec.rb

@@ -56,4 +56,20 @@ def deserialize(result)
     result[0]['name'].should == 'Berta'
   end
 
+  it "supports serialization_callbacks" do
+    class Horse
+      include DataMapper::Resource
+
+      property :id, Serial
+      property :name, String
+
+      def serialization_callback
+        { :external_name => "#{name}_external" }
+      end
+    end
+
+    horse = Horse.create(:name => 'legolas')
+    result = @harness.deserialize(YAML.dump(horse))
+    result['external_name'].should == 'legolas_external'
+  end
 end