加入类型转换逻辑，防止解码失败

db/task_db.py

@@ -178,9 +178,13 @@ class TaskDBOperator(BaseDBOperator):
             fields = []
             values = []
             # 需要序列化的字段
-            json_fields = ['groups', 'content_miniprogram', 'preview_recipients', 'content_link']
+            json_fields = ['groups', 'content_miniprogram', 'preview_recipients', 'content_link', 'weekly_days']
             
             for key, value in updates.items():
+                # 跳过空值字段
+                if value is None or (isinstance(value, list) and len(value) == 0):
+                    continue
+                    
                 fields.append(f"{key} = %s")
                 # 如果是需要序列化的字段，且值不是字符串类型，则进行序列化
                 if key in json_fields and not isinstance(value, str):