python - 模型子类 : override CharField max_length

Question

我有一个提供的数据库模式，我想为其创建一个 Django 应用程序。架构中的许多表共享一组通用的列，例如 name 和 date_created。这促使我创建一个包含这些列的抽象 Standard_model 类，并从中子类化相关模型。

不幸的是，某些表的 name 列具有不同的 max_length。我试图想出一种方法，让子类化模型将 max_length 值传递给抽象基类，但我一片空白。

有什么想法吗？

class Standard_model(models.Model):
    name = models.CharField(max_length=50)
    date_created = models.DateTimeField()

    class Meta:
        abstract = True

class MyModel(Standard_model):
    name = models.CharField(max_length=80)  # Can't do this.

Answer 1

不，你cannot override the name field definition :

In normal Python class inheritance, it is permissible for a child class to override any attribute from the parent class. In Django, this is not permitted for attributes that are Field instances (at least, not at the moment). If a base class has a field called author, you cannot create another model field called author in any class that inherits from that base class.

另见:

• In Django - Model Inheritance - Does it allow you to override a parent model's attribute?

并且，仅供引用，根据 model naming convention ，它应该被称为 StandardModel。