Question

def count_customers_per_period(self):
    if not self.request.GET.get('period'):
        period = self.request.GET['period']
        entry_date_production = datetime.datetime(2017, 6, 1)
        start_date = CustomerProfile.objects.filter(user__date_joined__gte=entry_date_production).\
                first().user.date_joined
        end_date = CustomerProfile.objects.last().user.date_joined

        def start_end_period(period):
            start = start_date - datetime.timedelta(period)
            end = start + datetime.timedelta(period)

        if period == 'day':
            while start < end:
                array = np.array([])
                count = CustomerProfile.objects.filter(user__date_joined__date=start_date).count()
                array = np.append(array, count)
                start_date += datetime.timedelta(1)
        elif period == 'week':
            start_end_period(7)
            while start < week:
                array = np.array([])
                count = CustomerProfile.objects.filter(user__date_joined__range=[start, end])
                array = np.append(array, count)
                start = end + datetime.timedelta(1)
                end = start + datetime.timedelta(7)
        elif period == 'month':
            start_end_period(months=1)
            while start < end:
                array = np.array([])
                count = CustomerProfile.objects.filter(user__date_joined__range=[start, end])
                array = np.append(array, count)
                start = end + datetime.timedelta(1)
                end = start + datetime.timedelta(months=1)
        elif period == 'year':
            start_end_period(years=1)
            while start < end:
                array = np.array([])
                count = CustomerProfile.objects.filter(user__date_joined__range=[start, end])
                array = np.append(array, count)
                start = end + datetime.timedelta(1)
                end = start + datetime.timedelta(years=1)
    return array

在这种方法中，我定义了start_end_period()函数，因为我需要你多次使用它。

问题：

每当我调用start函数时end和start_end_period()都没有实例化，这是正常的吗？
以这种方式将函数放入方法中是一个好习惯吗？

Answer 1

start和end是start_end_period的本地版本，您不会返回它们，所以是的，它们在其他地方没有定义是正常的。如果需要，您需要分配返回的值：

def start_end_period(period):
    start = start_date - datetime.timedelta(period)
    end = start + datetime.timedelta(period)
    return start, end
...

start, end = start_end_period(7)

我不会说这样的嵌套函数是一个好习惯。将此作为类中的单独方法更常见，并使用self.start_end_period(whatever)显式调用它。

变量未实例化

1 个答案: