envolver todo en una transacción

app/controllers/readings_controller.rb

@@ -6,6 +6,7 @@ class ReadingsController < ActionController::API
 
   # @see {https://docutopia.tupale.co/sutty:nodemecu:api}
   def create
+    Reading.transaction do
       reading = raspberry.readings.build reading_params
       reading.id = params[:transaction_uuid]
       # TODO: Verificar firma
@@ -20,11 +21,12 @@ class ReadingsController < ActionController::API
       end
 
       if reading.save
-      render plain: reading.uuid, status: :ok
+        render plain: reading.id, status: :ok
       else
         head :bad_request
       end
     end
+  end
 
   private