python - 如何修复Python中的 "AttributeError: type object has no attribute"？

Question

我在预设代码中添加一些代码来检查时间可用性，即 session 时间是否符合建议的时间表。但是，我不断收到以下错误。有人可以给我一些建议吗？非常感谢您抽出时间。

预设代码:

from datetime import datetime
class Meeting:
    def __init__(self, start_time, end_time):
        self.start_time = start_time
        self.end_time = end_time

我的代码:

def check_availability(meetings, proposed_time): 
    meeting_start = Meeting.datetime.start_time.hour 
    meeting_end = Meeting.datetime.end_time.hour  
    ok_time = datetime.proposed_time.hour   
    if meeting_start < ok_time < meeting_end:
        return True 
    else:
        return False 

meetings = [Meeting(datetime(2018, 8, 1, 9, 0, 0), datetime(2018, 8, 1, 11, 
0, 0)), Meeting(datetime(2018, 8, 1, 15, 0, 0), datetime(2018, 8, 1, 16, 0, 
0)), Meeting(datetime(2018, 8, 2, 9, 0, 0), datetime(2018, 8, 2, 10, 0, 0))]

print(check_availability(meetings, datetime(2018, 8, 1, 12, 0, 0)))
print(check_availability(meetings, datetime(2018, 8, 1, 10, 0, 0)))

Answer 1

您的代码引发了此异常:

AttributeError: type object 'Meeting' has no attribute 'datetime'

在这一行:

meeting_start = Meeting.datetime.start_time.hour

Python 告诉你 Meeting class 没有名为 datetime 的属性。这是真的:Meeting class是一个用于制作 session 对象(或实例)的工厂，这些对象有start_time和end_time属性，通过将日期时间实例传递给Meeting来设置的__init__方法。这些属性可以这样访问:

>>> meeting = Meeting(datetime(2018, 8, 1, 9, 0, 0), datetime(2018, 8, 1, 11, 
0, 0))
>>> print(meeting.start_time)
2018-08-01 09:00:00                                                                                                     
>>> print(meeting.end_time)                                                                                             
2018-08-01 11:00:00 

您的 check_availability 函数正在传递一个 session 列表，因此您需要循环该列表以检查是否有任何 session 与建议的 session 时间冲突。

def check_availability(meetings, proposed_time):
    # Loop over the list of meetings; "meeting"
    # is the meeting that you are currently inspecting.
    for meeting in meetings:
        # if proposed_time is between meeting.start_time
        # and meeting.end_time, return False
    # If you get through the list without returning False
    # then the proposed time must be ok, so return True.