我有三个相关的模型。第一个是DayOfWeek，它是一个日期标签和数字看起来是这样的：
class DayOfWeek(models.Model):
day = models.IntegerField()
label = models.CharField(max_length='20')
def __str__(self):
return self.label
每次同步数据库时，都会使用fixture填充这个类。接下来，我有一个事件模型，它如下所示：
class Event(AnnouncementBase, Location):
cost = CurrencyField(decimal_places=2, max_digits=10, blank=True, default=0.00)
start_date = models.DateField(default = datetime.now().date())
start_time = models.TimeField(default = datetime.now().time())
end_date = models.DateField(blank=True, default=None, null = True)
end_time = models.TimeField(blank=True, default=None, null = True)
最后，有一个复发。它有一个事件，用于为重复事件安排事件。看起来是这样的：
class Recurrence(models.Model):
event = models.ForeignKey(Event, related_name='event')
repeats = models.CharField(max_length = 50, choices = EVENT_REPEAT_CHOICES)
repeat_every = models.IntegerField(default = 1)
repeat_on = models.ManyToManyField(DayOfWeek, blank=True, null=True)
repeat_by = models.CharField(max_length = 50, choices = EVENT_REPEAT_BY_CHOICES, blank=True)
repeat_by_day_of_month = models.IntegerField(default = 0, blank=True)
repeat_ends = models.CharField(max_length = 50, choices = EVENT_REPEAT_END_CHOICES)
end_occurrences = models.IntegerField(default = 0, blank=True)
repeat_end_date = models.DateField(blank=True, default=None, null = True)
past_event_count = models.IntegerField(default=0, blank=True)
scheduled_events = models.ManyToManyField(Event, blank=True, default=None, related_name = 'scheduled_events')
is_active = models.BooleanField(blank=True, default=True)
def save(self, force_insert=False, force_update=False, using=None):
"""Overridden to create events the first time."""
self.full_clean()
#First do normal save so the data is there for the even scheduler.
self.save_base(force_insert=force_insert, force_update=force_update, using=using)
#If nothing is scheduled yet, schedule the first batch
if self.scheduled_events.count() == 0 and self.past_event_count == 0:
self.scheduleEvents()
def clean(self):
#repeat on weekly
if self.repeat_every < 1:
raise ValidationError('Repeat every must be at least 1.')
#weekly
if self.repeats == EVENT_REPEAT_CHOICES[1][0]:
#look for missing stuff
if not self.repeat_on:
raise ValidationError('Missing repeat on.')
最后，我有一个单元测试，它检查这个工作正常，看起来像这样：
def test_weekly_mon_wed_fri_occurrence(self):
event = Event()
event.start_date = date(year=2012, month=1, day=2)
event.start_time = time(hour=13, minute=30)
event.save()
recurrence = Recurrence()
recurrence.repeats = EVENT_REPEAT_CHOICES[1][0]
recurrence.repeat_on = (EVENT_DAY_CHOICES[1][0], EVENT_DAY_CHOICES[3][0], EVENT_DAY_CHOICES[5][0])
recurrence.repeat_ends = EVENT_REPEAT_END_CHOICES[0][0]
recurrence.event = event
nextEvent = recurrence.getNextEvent(event)
self.assertEquals(date(year=2012, month=1, day=4), nextEvent.start_date)
self.assertEquals(event.start_time, nextEvent.start_time)
nextNextEvent = recurrence.getNextEvent(nextEvent)
self.assertEquals(date(year=2012, month=1, day=6), nextNextEvent.start_date)
self.assertEquals(event.start_time, nextNextEvent.start_time)
每当测试运行时，它都会失败，出现以下异常。
ValueError:“Recurrence”实例需要具有主键值，才能使用多对多关系。
如果在clean方法中self.repeat_为on，则错误发生在行上。
我想重复是可选的，只有一些类型的复发需要它。我该怎么做？我错过了什么导致它失败？
最佳答案
在分配许多关系之前，您需要调用recurrence.save()。在你的代码中
recurrence.repeat_on = (EVENT_DAY_CHOICES[1][0], EVENT_DAY_CHOICES[3][0], EVENT_DAY_CHOICES[5][0])
不先保存重复周期。因为没有保存，所以递归还没有生成主键，Django ORM也不知道将什么作为外键插入M2M表。
关于python - Django对PrimaryKey的许多提示，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/9476010/