Django model for working with the Dropbox API

gistfile1.py

from django.db import models
from django.conf import settings

import dropbox

class RequestToken(models.Model):
    key = models.CharField(max_length=100)
    secret = models.CharField(max_length=100)
    user = models.ForeignKey('auth.User')


class AccessToken(models.Model):
    key = models.CharField(max_length=100)
    secret = models.CharField(max_length=100)
    user = models.ForeignKey('auth.User')
    

class DropBox(models.Model):
    #a dropbox can belong to either a userprofile or a shop
    userprofile = models.OneToOneField('main.UserProfile', null=True, blank=True)
    #it is always belongs to an access_token, which ultimately belongs to a user
    access_token = models.OneToOneField(AccessToken)
    
    def __unicode__(self):    
        return 'dropbox from %s' % self.userprofile.user.first_name
    
    @staticmethod
    def copy_item(source, destination, item):
        source_session = dropbox.session.DropboxSession(settings.DROPBOX_KEY, settings.DROPBOX_SECRET, settings.DROPBOX_ACCESS_TYPE)
        source_session.set_token(source.access_token.key, source.access_token.secret)
        source_client = dropbox.client.DropboxClient(source_session)
        destination_session = dropbox.session.DropboxSession(settings.DROPBOX_KEY, settings.DROPBOX_SECRET, settings.DROPBOX_ACCESS_TYPE)
        destination_session.set_token(destination.access_token.key, destination.access_token.secret)
        destination_client = dropbox.client.DropboxClient(destination_session)
        f = source_client.get_file(item.path)
        d = destination_client.put_file(item.path, f.read())
        destination.refresh_items()
        
    def add_file(self, file, path):
        session = dropbox.session.DropboxSession(settings.DROPBOX_KEY, settings.DROPBOX_SECRET, settings.DROPBOX_ACCESS_TYPE)
        session.set_token(self.access_token.key, self.access_token.secret)
        client = dropbox.client.DropboxClient(session)
        d = client.put_file(path, file.read())
        self.refresh_items()
        
    def refresh_items(self):
        #sync our local 'dropbox' with the real one, it's just the paths of files that need to be in sync
        self.dropbox_session = dropbox.session.DropboxSession(settings.DROPBOX_KEY, settings.DROPBOX_SECRET, settings.DROPBOX_ACCESS_TYPE)
        self.dropbox_session.set_token(self.access_token.key, self.access_token.secret)
        self.client = dropbox.client.DropboxClient(self.dropbox_session)
        paths = []
        for item in self.client.metadata('/')['contents']:
            DropBoxItem.objects.get_or_create(dropbox=self, path=item['path'])
            paths.append(item['path'])
        for item in DropBoxItem.objects.filter(dropbox=self):
            if item.path not in paths:
                item.delete()
            
            
class DropBoxItem(models.Model):
    dropbox = models.ForeignKey(DropBox)
    path = models.CharField(max_length=200)
    
    def __unicode__(self):
        path = self.path.replace('/', '')
        return path