Can't set ImageField url attribute

I want to change my ImageField's attribute, however I'm constantly getting the Can't set attribute error.

My model is

class Society(models.Model):
     name = models.CharField(max_length=200)
     slug = models.SlugField(unique=True)
     summary = models.TextField(blank=True,null=True)
     members = models.ManyToManyField(User,null=True,blank=True)
     gallery = models.ForeignKey(Gallery,null=True,blank=True)
     avatar = models.ImageField(upload_to=get_society_path)

     def save(self,*args,**kwargs):
          super(Society, self).save(*args,**kwargs)
          fix_avatar_path(self)

     def clean(self):
          if self.id:
               self.avatar.path = get_society_path(self,self.avatar.path)
               save_thumb(self.avatar.path)

And my helper functions are :

def get_society_path(instance,file开发者_如何学Pythonname):
     seperator_val = instance.id
     if seperator_val is None:
          seperator_val = get_time()
     return '%s/society_%s/%s' % (settings.UPLOAD_ROOT,seperator_val,time_to_name(filename))

def fix_avatar_path(instance):
     org_society_path = get_society_path(instance,instance.avatar.name)
     make_upload_dir(org_society_path)
     move(instance.avatar.path,org_society_path)
     os.rmdir(os.path.dirname(instance.avatar.path))
     instance.clean()

The problem is :

I want to save my society directories as society_society_id. But normally, I can't assign any id before the model is saved. So i'm creating a tmp file whose name is a time value.Then to reach societies folder, I want to rename this file. So, my fix_avatar simply moves the tmp file's content to society_(society_id) folder after the society is saved. So far so good everything works well. However, my society's ImageField still holds the previously created folder. In order to change it's value, I found that i can use clean method.(from this SO question) But still i'm getting the same result, the path doesn't change, and gives the "can't set attribute" response.

Any idea ??

Not sure, if this was ever changed in Django since this question was asked. A ticket about this not being possible still exists: https://code.djangoproject.com/ticket/15590

However, you actually can change the path by doing it like this:

self.avatar = 'uploads/example/path/'

What also does the job:

self.avatar.name = 'uploads/example/path/'

It has worked for us in several occasions.

The problem is here:

self.avatar.path = get_society_path(self,self.avatar.path)

You cannot change the value of the path attribute in FileField/ImageField instances, it's readonly. There is a proposal to change this in Django 1.4