Question

我的应用程序中有此模型，该模型旨在根据save（）中添加的方法自动生成其主键。
但是，对于每个对象，我都希望对某些字段进行更新。现在，无论何时我在管理端进行更新（测试用例），它都会创建PK的新记录，而不是更新现有记录。关于如何解决这个问题有什么想法吗？

class DeploymentTask(models.Model):
    deployment_id = models.CharField(
        'Deployment Task ID', primary_key=True, max_length=25, editable=False)
    title = models.CharField(max_length=100)
    current_status = FSMField('Current Status',
                              default=STATES[0], choices=STATES)
    site_id = models.ForeignKey(
        Site, related_name='+', on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    refuel_record = models.ManyToManyField(RefuelRecord)

    def __str__(self):
        """String for representing the Model object."""
        return self.deployment_id

    class Meta:
        db_table = 'rm_deployment_task'
        verbose_name_plural = 'Deployment Tasks'

    def get_absolute_url(self):
        return reverse('deployment_id-view', args=[str(self.deployment_id)])

    def save(self):
        today = datetime.datetime.now()
        ticket_count = DeploymentTask.objects.filter(
            created_at__year=today.year, created_at__month=today.month).count() + 1
        new_task_id = 'DPT-' + str(str(datetime.date.today().year)) + str(
            datetime.date.today().month).zfill(2) + str(
            datetime.date.today().day).zfill(2) + '-' + str(ticket_count).zfill(6)
        self.deployment_id = new_task_id
        super(DeploymentTask, self).save()

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Answer 1

您总是在保存方法中将self.deployment_id设置为新值。
Django尝试执行UPDATE ... WHERE deployment_id = %，但尚无具有此ID的记录（至少如果您要在不同日期保存“旧”对象或具有不同的ticket_count）
如果您要更新deployment_id以外的其他字段，则只需不设置self.deployment_id（如果已设置）。如果要更新deployment_id，则没有直接的方法，因为它用作主键（但是您可以记住旧的pk，并在save中创建新对象后删除该对象。）

在Django docs中了解更多信息。

Answer 2

这是我更新的代码，对我有用...

def make_id():
    today = datetime.datetime.now()
    ticket_count = DeploymentTask.objects.filter(
                created_at__year=today.year, created_at__month=today.month).count() + 1
    new_task_id = 'DPT-' + str(str(datetime.date.today().year)) + str(
            datetime.date.today().month).zfill(2) + str(
            datetime.date.today().day).zfill(2) + '-' + str(ticket_count).zfill(6)  
    return new_task_id
class DeploymentTask(models.Model):
    deployment_id = models.CharField(
        'Deployment Task ID', primary_key=True, max_length=25, editable=False, default=make_id)
    title = models.CharField(max_length=100)
    current_status = FSMField('Current Status',
                              default=STATES[0], choices=STATES)
    site_id = models.ForeignKey(
        Site, related_name='+', on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    refuel_record = models.ManyToManyField(RefuelRecord)

    def __str__(self):
        """String for representing the Model object."""
        return self.deployment_id

    class Meta:
        db_table = 'rm_deployment_task'
        verbose_name_plural = 'Deployment Tasks'

    def get_absolute_url(self):
        return reverse('deployment_id-view', args=[str(self.deployment_id)])

Django save（）总是创建一个新对象

2 个答案: