为什么Django不承认我的类变量?

I've defined the following form class in a Django project (Django 1.11, Python 3.5), but when I execute python3 manage.py runserver, I receive a

我在Django项目(Django 1.11, Python 3.5)中定义了以下表单类，但是在执行python3 manage时。py runserver，我收到a

 NameError: name 'month_names' is not defined

---

class MonthForm(forms.Form):
    month_names = [
        'January',
        'February',
        'March',
        'April',
        'May',
        'June',
        'July',
        'August',
        'September',
        'October',
        'November',
        'December'
        ]
    MONTH_CHOICES = [(i + 1, month_names[i]) for i in range(len(month_names))]
    month = forms.ChoiceField(choices=MONTH_CHOICES, label='Month',
                              widget=forms.Select())

I can't figure out why this doesn't work. I've noticed that if I move the initial month_names assignment outside of the class definition, then it works. Any explanation would be greatly appreciated. Thank you in advance.

我搞不懂为什么这行不通。我注意到，如果我将最初的月度名称赋值移动到类定义之外，那么它就可以工作。如有任何解释，将不胜感激。提前谢谢你。

1 个解决方案

#1

The Form metaclass - DeclarativeFieldsMetaclass - does not allow you to create (and by extension, bind) arbitrary objects that are not fields (i.e. instance of django.forms.fields.Field) on the class.

表单元类——DeclarativeFieldsMetaclass——不允许您在类上创建(并通过扩展绑定)非字段的任意对象(例如django.forms.fields.Field的实例)。

You'll have to declare such arbitrary objects outside the Form subclass.

您必须在表单子类之外声明这些任意对象。