I wrote 3 models:
...
def generate_mugshot(instance, filename):
filename, ext = os.path.splitext(filename)
return "mugshot/%s/%s%s" % (instance.id, uuid4(), ext)
def generate_team_photo(instance, filename):
filename, ext = os.path.splitext(filename)
return "team/%s/%s%s" % (instance.id, uuid4(), ext)
def generate_gift_photo(instance, filename):
filename, ext = os.path.splitext(filename)
return "gift/%s/%s%s" % (instance.id, uuid4(), ext)
class User(AbstractUser):
...
mugshot = models.ImageField('头像', upload_to= generate_mugshot,
validators=[check_image_extension], null=True, blank=True)
class Team(models.Model):
...
photo = models.ImageField('队标', upload_to= generate_team_photo,
validators=[check_image_extension], blank=True, null=True)
class Gift(models.Model):
...
photo = models.ImageField('图片', upload_to= generate_gift_photo,
validators=[check_image_extension], null=True, blank=True)
If I want to add a new model, I have to write a new duplicate function
"generate_something(instance, filename)", it is not pythonic. So I modify
it to following code:
def generate_attachment_by_id(prefix):
def _return_function(instance, filename):
filename, ext = os.path.splitext(filename)
return "%s/%s/%s%s" % (prefix, instance.id, uuid4(), ext)
return _return_function
...
class User(AbstractUser):
mugshot = models.ImageField('头像', upload_to=generate_attachment_by_id(
'mugshot'), validators=[check_image_extension], null=True, blank=True)
class Team(models.Model):
photo = models.ImageField('队标', upload_to=generate_attachment_by_id(
'team'), validators=[check_image_extension], blank=True, null=True)
class Gift(models.Model):
photo = models.ImageField('图片', upload_to=generate_attachment_by_id(
'gift'), validators=[check_image_extension], null=True, blank=True)
Then I execute makemigrations, an error raised:
ValueError: Could not find function _return_function in app.account.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.
For more information, see
https://docs.djangoproject.com/en/1.10/topics/migrations/#serializing-values
So, how to solve the problem?
Thank you for helping me...
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