diff --git a/lib/service/tools.dart b/lib/service/tools.dart
index 69767b4..1bfc245 100644
--- a/lib/service/tools.dart
+++ b/lib/service/tools.dart
@@ -1 +1,5 @@
 String generateId() => DateTime.now().millisecondsSinceEpoch.toString();
+
+String getIsoDateString(DateTime dateTime) {
+  return dateTime.toIso8601String().substring(0, 10);
+}