Merge pull request #1086 from noaccOS/refactor/appengine-device-select-exandra

refactor(appengine): port Device select queries to exandra

Author: davidebriani

apps/astarte_appengine_api/lib/astarte_appengine_api/device/astarte_value.ex

@@ -50,14 +50,22 @@ defmodule Astarte.AppEngine.API.Device.AstarteValue do
     Base.encode64(value)
   end
 
-  def to_json_friendly(value, :datetime, opts) do
+  def to_json_friendly(value, :datetime, opts) when is_integer(value) do
     if opts[:keep_milliseconds] do
       value
     else
       DateTime.from_unix!(value, :millisecond)
     end
   end
 
+  def to_json_friendly(value, :datetime, opts) when is_struct(value, DateTime) do
+    if opts[:keep_milliseconds] do
+      DateTime.to_unix(value, :millisecond)
+    else
+      value
+    end
+  end
+
   def to_json_friendly(value, :longintegerarray, opts) do
     for item <- value do
       to_json_friendly(item, :longinteger, opts)