Question

使用motor tutorial中的示例代码。

from tornado import gen

db = motor.MotorClient('localhost', 1235).open_sync().packmon

@gen.coroutine
def do_find():
    cursor = db.test_collection.find()
    for document in (yield cursor.to_list(length=100)):
        print document

tornado.ioloop.IOLoop.current().run_sync(do_find)

获取追溯：

Traceback (most recent call last):
  File "app_main.py", line 51, in run_toplevel
  File "chat.py", line 22, in <module>
    tornado.ioloop.IOLoop.current().run_sync(do_find)
  File "/home/user/venv/packmon-pypy/site-packages/tornado/ioloop.py", line 370, in run_sync
    return future_cell[0].result()
  File "/home/user/venv/packmon-pypy/site-packages/tornado/concurrent.py", line 129, in result
    raise_exc_info(self.__exc_info)
  File "/home/user/venv/packmon-pypy/site-packages/tornado/gen.py", line 221, in wrapper
    runner.run()
  File "/home/user/venv/packmon-pypy/site-packages/tornado/gen.py", line 507, in run
    yielded = self.gen.send(next)
  File "chat.py", line 19, in do_find
    for document in (yield cursor.to_list(length=100)):
  File "/home/user/venv/packmon-pypy/site-packages/motor/__init__.py", line 1465, in to_list
    check_callable(callback, required=True)
  File "/home/user/venv/packmon-pypy/site-packages/motor/__init__.py", line 74, in check_callable
    raise TypeError("callback is required")
TypeError: callback is required

文档说如果没有传递回调，它应返回Future，但它会抛出异常。使用gen.Task完成工作，但我不明白为什么教程中的简单示例不起作用。

Answer 1

您使用了“最新”教程和“稳定”代码。 Read the "stable" tutorial instead.

背景：Motor on PyPI is at version 0.1.2。版本0.1.2是当前具有基于回调的API的“稳定”版本。正如“稳定”教程所示，您可以将其与gen.Task一起使用。正如本教程将告诉您的那样，您应该使用motor.Op，这与gen.Task具有更好的异常语义。

您正在阅读的“最新”教程反映了我在GitHub上的Motor主分支中的极不稳定的代码。这将在未来几个月内作为Motor 0.2发布，并成为新的“稳定”。同时，请遵循当前的“稳定”文档。

电机错误：需要回调

1 个答案: