无法保存模型，出现错误：“TypeError 预期字符串或类似字节的对象”

Question

我正在尝试从几个模型中获取信息并在模型日历中生成表条目。我无法保存日历条目。得到一个类型错误。最终，我希望这个系统根据最后一个预定的星期一将日历条目添加到未来。但目前这项任务只会在星期一执行。但如果可能的话，我希望能够提前一周以上。

模板：

<form action="{% url 'portal:custom_admin' %}" method="post">
    {% csrf_token %}
    <div style="background-color:red; width:15%;">
        <button name="submit">Project</button>
        DANGER! Only click on mondays, until future projecter can go based off futuremost monday generated into Calendar
    </div>
</form>

我正在苦苦挣扎的视图：

def custom_admin(request):
"""
Displays MaxSettings, also
Takes time_slots and create a week of it into the future (only should be done on mondays)
Note:eventually this should be able to generate from the last monday in the calendar instead of today
"""
max_settings = MaxSettings.objects.filter()
time_slots = TimeSlots.objects.filter()

if request.method != 'POST':
    pass
    # Do nothing
else:
    # Project A week forward
    for slot in time_slots:
         #there will be an if statement for each weekday
        if slot.day.weekday == 'Monday':
            new_entry = Calendar(
                date=datetime.timedelta(days=7),
                timeslot_A=slot.timeslot_A,
                timeslot_B=slot.timeslot_B,
                booked=False
            )
            new_entry.save()
            return HttpResponseRedirect(reverse('portal:custom_admin'))

calendar = Calendar.objects.filter()

context = {
    'max_settings': max_settings,
    'calendar': calendar,
}
return render(request, 'portal/custom_admin.html', context)

以下是相关模型：

class MaxSettings(models.Model):
"""
Everyweek day has its own specified open/close time, time slots along with number of available jobs
"""
MONDAY = 'Monday'
TUESDAY = 'Tuesday'
WEDNESDAY = 'Wednesday'
THURSDAY = 'Thursday'
FRIDAY = 'Friday'
SATURDAY = 'Saturday'
SUNDAY = 'Sunday'
WEEKDAY_CHOICES = (
    (MONDAY, 'monday'),
    (TUESDAY, 'tuesday'),
    (WEDNESDAY, 'wednesday'),
    (THURSDAY, 'thursday'),
    (FRIDAY, 'friday'),
    (SATURDAY, 'saturday'),
    (SUNDAY, 'sunday'),
)
weekday = models.CharField(max_length=9, choices=WEEKDAY_CHOICES, )
operating = models.BooleanField()
start_work_time = models.TimeField()
end_work_time = models.TimeField()

def __str__(self):
    """Return a string representation of the model."""
    return self.weekday


class TimeSlots(models.Model):
"""time slots along with number of available jobs for that slot"""
day = models.ForeignKey(MaxSettings, on_delete=models.CASCADE)
timeslot_A = models.TimeField()
timeslot_B = models.TimeField()
max_jobs = models.PositiveSmallIntegerField()

def __str__(self):
    """Return a string representation of the model."""
    return '%s %s %s' % (self.timeslot_A, self.timeslot_B, self.day)


class Calendar(models.Model):
"""
this will get it details from TimeSlots and be generated into the future from the  MaxSettings
"""
date = models.DateField()
timeslot_A = models.TimeField()
timeslot_B = models.TimeField()
booked = models.BooleanField()

错误详情：

TypeError at /custom_admin/

expected string or bytes-like object

Request Method:     POST
Request URL:    http://127.0.0.1:8000/custom_admin/
 Django Version:    2.0
Exception Type:     TypeError
Exception Value: expected string or bytes-like object

Exception Location:         error location: /site-packages/django/utils/dateparse.py in parse_date, line 74

Answer 1

我的猜测是发生错误是因为您使用 datetime.timedelta 作为 Calendar 的 date 属性的值> 进入。 Django 需要的是 datetime.date。 更准确地说，Django 需要一个日期（例如：“2018-01-17”），而您只提供两个日期之间的差异（在您的情况下：“7 天”）。您的代码应该做的是计算下周一的日期，然后将该值（转换为 datetime.date）传递给 Calendar.date 属性。