[FIX] encoding update node

src/Gargantext/API/Node/Update.hs

@@ -34,8 +34,6 @@ import Test.QuickCheck.Arbitrary
 import Data.Maybe (Maybe(..))
 import Control.Concurrent (threadDelay)
 
-
-
 ------------------------------------------------------------------------
 data UpdateNodeParams = UpdateNodeParamsList  { methodList  :: Method      }
                       | UpdateNodeParamsGraph { methodGraph :: GraphMetric }
@@ -61,8 +59,12 @@ data Charts = Sources | Authors | Institutes | Ngrams | All
 
 ------------------------------------------------------------------------
 -- TODO unPrefix "pn_" FromJSON, ToJSON, ToSchema, adapt frontend.
-instance FromJSON  UpdateNodeParams
-instance ToJSON    UpdateNodeParams
+instance FromJSON  UpdateNodeParams where
+  parseJSON = genericParseJSON (defaultOptions { sumEncoding = ObjectWithSingleField })
+
+instance ToJSON    UpdateNodeParams where
+  toJSON = genericToJSON (defaultOptions { sumEncoding = ObjectWithSingleField })
+  
 instance ToSchema  UpdateNodeParams
 instance Arbitrary UpdateNodeParams where
   arbitrary = do