Django對很多主訴主鍵

Question

我有三個相關的模型。第一個被稱爲DayOfWeek，這是一天的標籤和數字。它看起來像這樣：

class DayOfWeek(models.Model): 
    day = models.IntegerField() 
    label = models.CharField(max_length='20') 

    def __str__(self): 
    return self.label 

這個類是使用固定每次我syncdb.Next時候，我有一個事件模型填充，它看起來像這樣：

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) 

最後，有復發。它有一個事件，用於安排重複事件的事件。它看起來像這樣：

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.') 

最後，我有這個檢查工作的很好，它看起來像這樣的單元測試：

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) 

每當測試運行失敗，但下列情況除外。 ValueError：在可以使用多對多關係之前，'Recurrence'實例需要具有主鍵值。

如果在clean方法中使用self.repeat_on，則會發生錯誤。

我想repeat_on是可選的，只有某些類型的重複需要它。我如何完成這項工作？我錯過了什麼導致它失敗？

Answer 1

您需要在分配Many2 Many關係之前先致電recurrence.save()。在你的代碼你做

recurrence.repeat_on = (EVENT_DAY_CHOICES[1][0], EVENT_DAY_CHOICES[3][0], EVENT_DAY_CHOICES[5][0]) 

沒有先保存再發生。因爲它沒有保存，所以循環沒有生成主鍵，並且Django ORM不知道如何將外鍵作爲外鍵插入到M2M表中。