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我在overwritter ModelForm的save()方法中遇到django admin的问题。Django管理员ModelForm,保存计算相关
models.py
class Reservation(models.Model):
status = models.PositiveSmallIntegerField(choices=STATUS, default=0)
creation_date = models.DateTimeField(auto_now_add=True)
date_start = models.DateField()
date_end = models.DateField()
service = models.ForeignKey(Service, on_delete=models.CASCADE)
class ReservationItem(models.Model):
quantity = models.IntegerField()
unit_price = models.DecimalField(max_digits=10, decimal_places=2)
unit_tax = models.DecimalField(max_digits=10, decimal_places=2)
row_total = models.DecimalField(max_digits=10, decimal_places=2)
row_total_incl_tax = models.DecimalField(max_digits=10, decimal_places=2)
reservation = models.ForeignKey(Reservation, on_delete=models.CASCADE, related_name='items')
resource = models.ForeignKey(Resource, on_delete=models.CASCADE)
项目从服务衍生,通过可用性查询预约,所以it've书面管理员自定义的ModelForm。
admin.py
class ReservationModelForm(forms.ModelForm):
def clean(self):
if 'service' in self.cleaned_data:
self._check_availability()
return self.cleaned_data
def _check_availability(self):
'''do some stuff an get items ad an array of ReservationItems instances created like this:
ReservationItem(
resource=avail_resource,
quantity=resource_type.quantity,
unit_price=resource.unit_price,
unit_tax=resource.unit_price*resource.tax.percentage,
row_total=resource.unit_price*resource_type.quantity,
row_total_incl_tax=...
)'''
self.cleaned_data['items'] = items
# then the save method
def save(self, commit=True):
reservation = super(ReservationModelForm, self).save(commit=commit)
if not self.instance.id:
service = self.cleaned_data.get('service')
....
reservation.items.set(self.cleaned_data['items'], bulk=False)
return reservation
class ReservationAdmin(admin.ModelAdmin):
form = ReservationModelForm
现在我得到的是一个错误:save() prohibited to prevent data loss due to unsaved related object 'reservation'
。
但是我不能先保存保留,因为我需要原子保存,我该如何解决?
当然,你需要先保存预订。您希望如何知道要保存在'ReservationItem'的'Reservation'字段中的ID?原子的保存无关紧要:原子事务是封装在['transaction.atomic']中的事务(https://docs.djangoproject.com/en/1.11/topics/db/transactions/#django.db .transaction.atomic)上下文。 – spectras
好的你是对的,但是如果ReservationItems里面有一个内联函数,它们将被保存在一个包含父实例的事务中。我想模拟同样的事情 –
简单:通过在其上面添加'@ transaction.atomic(savepoint = False)'装饰器,手动将存储方法标记为单个事务。或者在方法中使用'with transaction.atomic(savepoint = False)'。或者更好的是:在你看来,而不是你的形式。表单不应涉及交易的结构。 – spectras