Python &引用；有时"；使用Peewee ORM在PostgreSQL上获取接口错误

我正在使用Python和PostgreSQL 9.3构建一个网站。到目前为止，事情进展得很顺利，但我现在遇到了一些麻烦。我有时会收到一个

接口错误：连接已关闭

。我得到它的代码如下：

pendingOrders_q = CustomerOrder\
    .select()\
    .where(CustomerOrder.status == CustomerOrder.STATUS_PENDING)\
    .where(CustomerOrder.expiration < datetime.utcnow())

if len(list(pendingOrders_q)) > 0:
    # do some stuff here..

[编辑] 我现在突然也得到了该行的以下错误：

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/apscheduler/scheduler.py", line 512, in _run_job
    retval = job.func(*job.args, **job.kwargs)
  File "/home/kramer65/xs/app/order_management.py", line 207, in checkForDetails
    for order in paidInOrders_q:
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 1411, in next
    obj = self.iterate()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 1392, in iterate
    row = self.cursor.fetchone()
InterfaceError: cursor already closed

---

此外，它还导致使用

pymysql

引擎。

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/apscheduler/scheduler.py", line 512, in _run_job
    retval = job.func(*job.args, **job.kwargs)
  File "/home/kramer65/xs/app/order_management.py", line 207, in checkForDetails
    for order in paidInOrders_q:
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 1411, in next
    obj = self.iterate()
  File "/usr/local/lib/python2.7/dist-packages/peewee.py", line 1392, in iterate
    row = self.cursor.fetchone()
InterfaceError: cursor already closed