From 2b4e3ad5c661956a8d7edaae72164f6b189e2fec Mon Sep 17 00:00:00 2001
From: Oleg A <t0rr@mail.ru>
Date: Wed, 7 Jul 2021 02:21:15 +0300
Subject: [PATCH] fix: optional list field serialize-deserialize (#622)

---
 aiogram/types/fields.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/aiogram/types/fields.py b/aiogram/types/fields.py
index 022b9b72..40b0da50 100644
--- a/aiogram/types/fields.py
+++ b/aiogram/types/fields.py
@@ -129,6 +129,9 @@ class ListField(Field):
         super(ListField, self).__init__(*args, default=default, **kwargs)
 
     def serialize(self, value):
+        if value is None:
+            return None
+
         result = []
         serialize = super(ListField, self).serialize
         for item in value:
@@ -136,6 +139,9 @@ class ListField(Field):
         return result
 
     def deserialize(self, value, parent=None):
+        if value is None:
+            return None
+
         result = []
         deserialize = super(ListField, self).deserialize
         for item in value: