diff --git a/Data/Library.hs b/Data/Library.hs
--- a/Data/Library.hs
+++ b/Data/Library.hs
@@ -13,7 +13,7 @@
 , new
 , unsafeGetItem
 , getItem
--- , testItem
+-- , testItems
 )
 
 where
@@ -23,15 +23,19 @@
 import Data.Sequence (Seq, adjust, (|>))
 import qualified Data.Sequence as Seq
 import Data.Time.Clock (UTCTime)
-import Data.Library.UUIRI (UUIRI)
+import Data.Library.UUIRI (UUIRI, iri, uuid, toUUIRI)
 import Data.Foldable (toList)
-import Data.Aeson (ToJSON(toJSON), FromJSON(parseJSON), object, (.=), (.:), Value(Object, Null))
+import Data.Aeson (ToJSON(toJSON), FromJSON(parseJSON), object, (.=), (.:), (.:?), (.!=), Value(Object, Null))
 import Data.Aeson.Types (Parser)
 import Control.Applicative ((<$>), (<*>))
 import Control.Monad (mzero)
 import qualified Data.HashMap.Strict as HM
 import Data.SafeCopy (deriveSafeCopy, base)
+import Data.Maybe (fromMaybe)
 
+import Keys.UUID (nil, UUID(..))
+import Data.UUID hiding (nil, UUID)
+
 -- | A Library is just a rebranded Seq
 type Library = Seq LibraryItem
 
@@ -150,21 +154,29 @@
     } 
 
 
--- testItem t = Item 0 "teste" (Just "isto é um teste") t t 0 (Left (empty,empty))
+{-
+testItems t = 
+    [ Item 0 "teste" (Just "isto eh um teste") t t 0 (Left (IS.singleton 1,IS.singleton 2))
+    , f1 t, d1 t
+    ]
+f1 t = Item 1 "f1" (Just "ficheiro 1") t t 0 (Right $ toUUIRI (UUID $ fromWords 1 2 3 4) "http://blah.com/f1.txt")
+d1 t = Item 2 "d1" (Just "dir 1") t t 0 (Left (empty, empty))
+-}
 
 instance ToJSON LibraryItem where
     toJSON Deleted = Null
-    toJSON (Item iid iname idesc icreated imodified iparent itype) = 
-       object ["id" .= iid, "name" .= iname, "description" .= idesc
-              , "created" .= icreated, "modified" .= imodified
-              , "parent" .= iparent, "item" .= typeJson
-              ] 
+    toJSON (Item iid iname idesc icreated imodified iparent itype) = object $
+        case itype of
+            Right f -> ("uuid", toJSON (uuid f)) : ("url", toJSON (iri f)) :
+                       ("subdirectories", Null) : ("files",Null) : common
+            Left (f,d) -> ("uuid", Null) : ("url", Null) : 
+                          ("subdirectories", toJSON d) : ("files", toJSON f) : 
+                          common
         where 
-            typeJson = case itype of
-                        Left (f,d) -> object [ "files" .= f 
-                                             , "subdirectories" .= d
-                                             ]
-                        Right f -> toJSON f
+            common = ["id" .= iid, "name" .= iname, "description" .= idesc
+                     , "created" .= icreated, "modified" .= imodified
+                     , "parent" .= iparent 
+                     ]
 
 instance FromJSON LibraryItem where
     parseJSON Null = return Deleted
@@ -174,17 +186,18 @@
                                 <*> i .: "created"
                                 <*> i .: "modified"
                                 <*> i .: "parent"
-                                <*> lookForItem i
-        where 
-              -- WARNING: HM.lookup might change if aeson changes the type 
-              lookForItem i = maybe emptyDir getType $ HM.lookup "item" i 
-              getType t = case t of 
-                            Object o -> toDirectory <$> o .: "files"
-                                                    <*> o .: "subdirectories"
-                            _ -> Right <$> parseJSON t
-              toDirectory :: IntSet -> IntSet -> Either Directory UUIRI
-              toDirectory f d = Left (f,d)
-              emptyDir = return $ Left (empty, empty)
+                                <*> do fuuid  <- i .:? "uuid"
+                                       furl   <- i .:? "url"
+                                       dfiles <- i .:? "files"
+                                       ddirs  <- i .:? "subdirectories"
+                                       return $ case furl of
+                                         Nothing -> makeDir dfiles ddirs
+                                         Just f -> makeUUIRI fuuid f
+        where
+            makeDir :: Maybe IntSet -> Maybe IntSet -> Either Directory UUIRI
+            makeDir i1 i2 = Left (fromMaybe (IS.empty) i1, fromMaybe (IS.empty) i2)
+            makeUUIRI :: Maybe UUID -> Text -> Either Directory UUIRI
+            makeUUIRI u iri = Right $ toUUIRI (fromMaybe nil u) iri
     parseJSON _          = mzero
 
 isDir :: LibraryItem -> Bool
diff --git a/dirfiles.cabal b/dirfiles.cabal
--- a/dirfiles.cabal
+++ b/dirfiles.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                dirfiles
-version:             0.1.0.0
+version:             0.1.0.1
 -- synopsis:            
 description:         Simple datatype to represent a library with files and folders
 license:             BSD3