Augments Mongoid adapter by handling case where attribute is an array

lib/cancan/model_adapters/mongoid_adapter.rb

@@ -6,7 +6,14 @@ module CanCan
       end
 
       def self.override_conditions_hash_matching?(subject, conditions)
-        conditions.any? { |k,v| !k.kind_of?(Symbol) }
+        conditions.any? do |k,v|
+          key_is_not_symbol = lambda { !k.kind_of?(Symbol) }
+          subject_value_is_array = lambda do
+            subject.respond_to?(k) && subject.send(k).is_a?(Array)
+          end
+
+          key_is_not_symbol.call || subject_value_is_array.call
+        end
       end
 
       def self.matches_conditions_hash?(subject, conditions)

spec/cancan/model_adapters/mongoid_adapter_spec.rb

@@ -42,6 +42,15 @@ if ENV["MODEL_ADAPTER"] == "mongoid"
         @ability.should be_able_to(:read, model)
       end
 
+      it "should be able to read hashes when field is array" do
+        one_to_three = MongoidProject.create(:numbers => ['one', 'two', 'three'])
+        two_to_five  = MongoidProject.create(:numbers => ['two', 'three', 'four', 'five'])
+
+        @ability.can :foo, MongoidProject, :numbers => 'one'
+        @ability.should be_able_to(:foo, one_to_three)
+        @ability.should_not be_able_to(:foo, two_to_five)
+      end
+
       it "should return [] when no ability is defined so no records are found" do
         MongoidProject.create(:title => 'Sir')
         MongoidProject.create(:title => 'Lord')