Django - 覆盖 Model.create() 方法? [英] Django - Overriding the Model.create() method?

问题描述

Django 文档仅列出覆盖 save() 和 delete() 的示例.但是，我想仅在创建模型时为我的模型定义一些额外的处理.对于熟悉 Rails 的人来说，这相当于创建一个 :before_create 过滤器.这可能吗?

The Django docs only list examples for overriding save() and delete(). However, I'd like to define some extra processing for my models only when they are created. For anyone familiar with Rails, it would be the equivalent to creating a :before_create filter. Is this possible?

推荐答案

重写 __init__() 会导致在实例化对象的 Python 表示时执行代码.我不知道 Rails，但是 :before_created 过滤器听起来像是在数据库中创建对象时要执行的代码.如果要在数据库中创建新对象时执行代码，则应覆盖 save()，检查对象是否具有 pk 属性.代码看起来像这样:

Overriding __init__() would cause code to be executed whenever the python representation of object is instantiated. I don't know rails, but a :before_created filter sounds to me like it's code to be executed when the object is created in the database. If you want to execute code when a new object is created in the database, you should override save(), checking if the object has a pk attribute or not. The code would look something like this:

def save(self, *args, **kwargs):
    if not self.pk:
        # This code only happens if the objects is
        # not in the database yet. Otherwise it would
        # have pk
    super(MyModel, self).save(*args, **kwargs)

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