在 Django 中修改 m2m 关系中的对象答案

【问题标题】：Modify objects in an m2m relation in Django在 Django 中修改 m2m 关系中的对象
【发布时间】：2014-03-23 11:14:05
【问题描述】：

我想在对象中添加属性，其中包括 m2m 字段。

models.py

class GamerQuestion(models.Model):
    gamer = models.ForeignKey(User)
    question = models.ManyToManyField(Question)
    test = models.ForeignKey(Test)

view.py

    for question in context['object_list'].question.all():
        question.foo = 'add_info'

    for question in context['object_list'].question.all():
        print(question.foo)

但是print(question.foo) 给了我这个错误：

Traceback (most recent call last):
  File "/home/user1/env/gemafication/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 114, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/user1/env/gemafication/local/lib/python2.7/site-packages/django/contrib/auth/decorators.py", line 22, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/home/user1/env/gemafication/local/lib/python2.7/site-packages/django/views/generic/base.py", line 69, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/user1/env/gemafication/local/lib/python2.7/site-packages/django/views/generic/base.py", line 87, in dispatch
    return handler(request, *args, **kwargs)
  File "/home/user1/env/gemafication/local/lib/python2.7/site-packages/django/views/generic/list.py", line 152, in get
    context = self.get_context_data()
  File "/home/user1/projects/db_autotest/app/knowledge_test/views.py", line 88, in get_context_data
    print(question.foo)
AttributeError: 'Question' object has no attribute 'foo'

我做错了什么？

【问题讨论】：

标签： python django object django-models m2m

【解决方案1】：

每次迭代都是从数据库中获取的新查询集，因此第二次迭代没有您在第一次迭代中设置的属性。

您可以在第一个循环之前转换为列表，然后迭代该列表而不是新的查询集。

【讨论】：