Merge ralph's changes to allow assigning nil to a mapping.

lib/attribute_mapper.rb

@@ -114,14 +114,12 @@ def verify_existence_of(attribute)
   module InstanceMethods
 
     private
-
-    def resolve_value_of(attribute, raw_value)
-      check_value = raw_value.is_a?(String) ? raw_value.to_sym : raw_value
-      mapping = self.class.send(attribute.to_s.pluralize)
-      raise ArgumentError, "`#{check_value}' not present in attribute mapping `#{mapping.inspect}'" unless mapping.to_a.flatten.include? check_value
-      mapping[check_value] || check_value
-    end
-
+      def resolve_value_of(attribute, raw_value)
+        check_value = raw_value.is_a?(String) ? raw_value.to_sym : raw_value
+        mapping = self.class.send(attribute.to_s.pluralize)
+        raise ArgumentError, "`#{check_value}' not present in attribute mapping `#{mapping.inspect}'" unless mapping.to_a.flatten.include? check_value
+        mapping.include?(check_value) ? mapping[check_value] : check_value
+      end
   end
 
 end

test/attribute_mapper_test.rb

@@ -96,6 +96,28 @@ class AttributeMapperTest < Test::Unit::TestCase
       assert_equal [[["Open", :open], ["Closed", :closed]], {:selected => :open}], ticket.status_options(false)
     end
 
+    context "setting nil as a valid value in the mapping" do
+      setup do
+        Ticket.map_attribute :status, :to => mapping(:unanswered => nil)
+      end
+
+      should "allow setting the status by primitive value" do
+        assert_nothing_raised do
+          ticket.status = mapping[:unanswered]
+        end
+        assert_equal :unanswered, ticket.status
+        assert ticket.unanswered?
+      end
+
+      should "allow setting the status by symbol" do
+        assert_nothing_raised do
+          ticket.status = :unanswered
+        end
+        assert_equal :unanswered, ticket.status
+        assert ticket.unanswered?
+      end
+    end
+
   end
 
   #######