如何在ManyToMany表（Django）中添加列 [英] How to add column in ManyToMany Table (Django)

问题描述

从Django Book的例子中，我明白我是否创建了如下所示的模型：

From the example of Django Book, I understand if I create models as following:

from xxx import B

class A(models.Model):
    b = ManyToManyField(B)

Django将创建一个超过表A的新表（A_B），它有三列：

The Django would create a new table(A_B) beyond Table A, which has three columns:

• id


• a_id


• b_id

但现在我要添加一个新列表A_B，因此如果我使用普通的SQL，会很容易，但现在有人可以帮我吗？我在这本书中找不到任何有用的信息。

But now I want to add a new column in the Table A_B, thus would be very easy if I use normal SQL, but now anyone can help me how to do? I can't find any useful information in this book.

推荐答案

使用django也很简单！您可以通过使用来定义自己的多个中介表

It's very easy using django too! You can use through to define your own manytomany intermediary tables

文档提供了一个解决您的问题的示例：

Documentation provides an example addressing your issue:

Extra fields on many-to-many relationships

class Person(models.Model):
    name = models.CharField(max_length=128)

    def __unicode__(self):
        return self.name

class Group(models.Model):
    name = models.CharField(max_length=128)
    members = models.ManyToManyField(Person, through='Membership')

    def __unicode__(self):
        return self.name

class Membership(models.Model):
    person = models.ForeignKey(Person)
    group = models.ForeignKey(Group)
    date_joined = models.DateField()
    invite_reason = models.CharField(max_length=64)

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