def get(self, id, pk='id', deleted=False):
        try:
            if pk == 'id':
                id = int(id)
            if deleted:
                spec = {pk: id}
            else:
                spec = {pk: id, 'data': {'$exists': 1}}
            fields = {'_id': 0}
            row = self.db.docs.find_one(spec, fields)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return Document(**row)
        raise NotFoundError('%s %s not found' % (pk, id))
def image_thumbnail(filename):
    filepath = os.path.join(app.config.get('UPLOAD_FOLDER'), filename)
    im = Image.open(filepath)
    w, h = im.size

    if w > h:
        im.thumbnail((106, 106*h/w))
    else:
        im.thumbnail((106*w/h, 106))

    im.save(os.path.join(app.config.get('UPLOAD_FOLDER'), 
        os.path.splitext(filename)[0] + '_thumbnail' + os.path.splitext(filename)[1]))