Django Pickle Field在加载时对其模型实例的访问

Question

我有一个自定义django字段子类，用于存储自己的腌制类。有什么方法可以设置一个model属性，该属性指向数据库每次加载时在我的腌制类上的模型实例？到目前为止，我最好的猜测是在方法内部的解开过程中，to_python但是我不确定能否Field引用模型实例或类。

Answer 1

弄清楚了！

我__init__像这样覆盖了模型的方法：

class MyModel(models.Model):

    def __init__(self, *args, **kwargs):

        # Don't do any extra looping or anything in here because this gets called

        # at least once for every row in each query of this table

        self._meta.fields[2].model_instance = self

        super(MyModel, self).__init__(*args, **kwargs)

    field1 = models.TextField()

    field2 = models.PickleField()

    field3 = models.DateTimeField()

然后在我的字段子类中：

def to_python(self, value):

    # logic and unpickling, then right before your return:

    if hasattr(self, 'model_instance'): # avoid AttributeError if list, dict, etc.

        value.model_instance = self.model_instance

    return value