为 Django 1.7 重构调用

Question

我正在从 Django 1.6 升级到 1.7，我遇到了一个棘手的问题。我有一个像这样的个人资料图片的模型字段：

profile_image = models.ImageField(
    upload_to=get_user_uploadto_callable('photos'), null=True,
    verbose_name=_('photo'), blank=True)

...我的 get_user_uploadto_callable 看起来像这样：

def get_user_uploadto_callable(subdir):
    '''Return a callable that returns a custom filepath/filename
    for an uploaded file as per `get_user_upload_path`.

    '''

    def _callable(instance, filename):
        return get_user_upload_path(instance, subdir, filename)

    return _callable

然而，这不再被 Django 接受，并在我尝试进行迁移时导致此错误：

ValueError: Could not find function _callable in myproj.core.util.
Please note that due to Python 2 limitations, you cannot serialize unbound method functions (e.g. a method declared
and used in the same class body). Please move the function into the main module body to use migrations.
For more information, see https://docs.djangoproject.com/en/1.7/topics/migrations/#serializing-values

所以我需要将这个 _callable 移到方法之外（可能将其重命名为 user_uploadto_callable 之类的东西）但仍然可以访问传入的 subdir 参数。是否有一个干净的方式来做到这一点？

Answer 1

不可能使用 get_user_uploadto_callable 的结果作为 Python 2 中的可调用函数，但您可以定义一个函数来做同样的事情。

def profile_image_upload_to():
    # you can reduce this to one line if you prefer, I used
    # two to make it clearer how it works
    callable = get_user_uploadto_callable('photos')
    return callable()

class MyModel(models.Model):
    profile_image = models.ImageField(
        upload_to=profile_image_upload_to, null=True,
        verbose_name=_('photo'), blank=True)

为 Django 1.7 重构调用

Refactoring callable for Django 1.7

python

django

django-1.7