Django - 無法爲具有動態upload_to值的ImageField創建遷移

Question

我剛剛將我的應用升級到1.7（實際上仍在嘗試）。

這是我在models.py：

def path_and_rename(path): 
    def wrapper(instance, filename): 
     ext = filename.split('.')[-1] 
     # set filename as random string 
     filename = '{}.{}'.format(uuid4().hex, ext) 
     # return the whole path to the file 
     return os.path.join(path, filename) 
    return wrapper 

class UserProfile(AbstractUser): 
    #... 
    avatar = models.ImageField(upload_to=path_and_rename("avatars/"), 
           null=True, blank=True, 
           default="avatars/none/default.png", 
           height_field="image_height", 
           width_field="image_width") 

當我嘗試makemigrations，它拋出：

ValueError: Could not find function wrapper in webapp.models. 
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. 

Answer 1

我不知道這是否是OK的回答我的問題，但我只是想出了（我認爲）。

據this bug report，我修改了代碼：

from django.utils.deconstruct import deconstructible 

@deconstructible 
class PathAndRename(object): 

    def __init__(self, sub_path): 
     self.path = sub_path 

    def __call__(self, instance, filename): 
     ext = filename.split('.')[-1] 
     # set filename as random string 
     filename = '{}.{}'.format(uuid4().hex, ext) 
     # return the whole path to the file 
     return os.path.join(self.path, filename) 

path_and_rename = PathAndRename("/avatars") 

，然後在字段定義：

avatar = models.ImageField(upload_to=path_and_rename, 
           null=True, blank=True, 
           default="avatars/none/default.png", 
           height_field="image_height", 
           width_field="image_width") 

這爲我工作。

Answer 2

我有同樣的問題，但我有很多鏡像文件在我的模型

head = ImageField(upload_to=upload_to("head") 
icon = ImageField(upload_to=upload_to("icon") 
...etc 

我不想爲每列的ImageField我創建upload_to wraper FUNC。

所以，我只是創建了一個名爲包裝FUNC，它炒鍋

def wrapper(): 
    return 

---

我想是因爲我打開遷移文件，我發現這只是正常工作：

('head', models.ImageField(upload_to=wrapper)), 

我猜測這不是影響遷移過程