我的 django 模型 DateField 如何将 30 天添加到提供的值

// Update个

原帖下面的 comments 让我深思.我想这是到目前为止最好的解决方案:

from datetime import datetime, timedelta

class MyModel(models.Model):
   mydate = models.DateTimeField(default=datetime.now()+timedelta(days=30))

// 2. Update个

如果您想定义一个保存应该添加的天数的模型属性，您将需要覆盖save方法.到目前为止，我想不出一个更简单的方法.

解决方案:

class MyModel(models.Model):
  mydate = models.DateTimeField(editable=False)
  daysadded = models.IntegerField()

  def save(self):
    from datetime import datetime, timedelta
    d = timedelta(days=self.daysadded)

    if not self.id:
      self.mydate = datetime.now() + d
      super(MyModel, self).save()

正如beadingGuru已经建议的那样，您应该覆盖您的模型保存方法.

Example:

class MyModel(models.Model):
  mydate = models.DateTimeField(auto_now_add=True)      

  def save(self):
    from datetime import timedelta
    d = timedelta(days=30)

    // only add 30 days if it's the first time the model is saved
    if not self.id:
      // not saving the model before adding the timedelta gave me errors 
      super(MyModel, self).save()

      self.mydate += d

      // final save
      super(MyModel, self).save()

这对我来说不是最好的方式，因为你必须保存模型两次.但是使用AUTO_NOW_ADD要求您在创建myDate的DateTime实例之前首先保存模型.

另一种只需要一次保存的方法:

class MyModel(models.Model):
  mydate = models.DateTimeField(editable=False) // editable=False to hide in admin

  def save(self):
    from datetime import datetime, timedelta
    d = timedelta(days=30)

    // only add 30 days if it's the first time the model is saved
    if not self.id:
      self.mydate = datetime.now() + d
      super(MyModel, self).save()

希望这能帮上忙！