如何在django查询中每隔30秒从MYSQL数据库表中过滤数据？

Question

我的数据库表名tripcomment：

mysql> select * from orbit_tripcomments; 

+----+------------------------+------------+------------+---------+---------------------+ 
| id | comment    | citymap_id | ip_address | user_id | posted    | 
+----+------------------------+------------+------------+---------+---------------------+ 
| 2 | very nice comment    508 | 127.0.0.1 |  168 | 2014-11-20 08:25:19 | 
| 3 | I make plan for visite |  508 | 127.0.0.1 |  168 | 2014-11-20 08:33:17 | 
| 4 | i make a trip of manali|  508 | 127.0.0.1 |  168 | 2014-11-19 10:17:17 | 
| 5 | i make a trip of manali|  508 | 127.0.0.1 |  168 | 2014-11-20 10:18:26 | 

我的Django的查询是：

from datetime import datetime  
from datetime import timedelta 

tt = (datetime.utcnow() + timedelta(seconds=30)).strftime('%Y-%m-%d %H:%M:%S') 

t_comment = models.tripcomments.objects.filter(citymap_id=parent_mapid, 
               posted__gte=tt) 

但它返回一个空白列表。

Answer 1

你应该通过datetime实例DateTime场，不串：

from datetime import datetime, timedelta 

results = Item.objects.filter(pub_date__lt=datetime.now() - timedelta(hours=5))