added support for nested join conditions

lib/cancan/model_adapters/active_record_adapter.rb

@@ -66,11 +66,22 @@ module CanCan
         return conditions unless conditions.kind_of? Hash
         conditions.inject({}) do |result_hash, (name, value)|
           if value.kind_of? Hash
+            value = value.dup
             association_class = model_class.reflect_on_association(name).class_name.constantize
+            nested = value.inject({}) do |nested,(k,v)|
+              if v.kind_of? Hash
+                value.delete(k)
+                nested[k] = v
+              else
                 name = model_class.reflect_on_association(name).table_name.to_sym
-            value = tableized_conditions(value, association_class)
-          end
                 result_hash[name] = value
+              end
+              nested
+            end
+            result_hash.merge!(tableized_conditions(nested,association_class))
+          else
+            result_hash[name] = value
+          end
           result_hash
         end
       end

spec/cancan/model_adapters/active_record_adapter_spec.rb

@@ -207,6 +207,16 @@ if ENV["MODEL_ADAPTER"].nil? || ENV["MODEL_ADAPTER"] == "active_record"
       @ability.model_adapter(Article, :read).conditions.should == "'t'='t'"
     end
 
+    it "should return appropriate sql conditions in complex case with nested joins" do
+      @ability.can :read, Comment, :article => { :category => { :visible => true } }
+      @ability.model_adapter(Comment, :read).conditions.should == { Category.table_name.to_sym => { :visible => true } }
+    end
+
+    it "should return appropriate sql conditions in complex case with nested joins of different depth" do
+      @ability.can :read, Comment, :article => { :published => true, :category => { :visible => true } }
+      @ability.model_adapter(Comment, :read).conditions.should == { Article.table_name.to_sym => { :published => true }, Category.table_name.to_sym => { :visible => true } }
+    end
+
     it "should not forget conditions when calling with SQL string" do
       @ability.can :read, Article, :published => true
       @ability.can :read, Article, ['secret=?', false]