Build a cart from a json file

def load(self, json_file):
        """
        Build a cart from a json file
        """
        cart_file = os.path.join(CART_LOCATION, json_file)
        try:
            cart_body = juicer.utils.read_json_document(cart_file)
        except IOError as e:
            juicer.utils.Log.log_error('an error occured while accessing %s:' %
                    cart_file)
            raise JuicerError(e.message)

        self.cart_name = cart_body['_id']

        if cart_body['current_env'] == '':
                self.current_env = juicer.utils.get_login_info()[1]['start_in']
        else:
            self.current_env = cart_body['current_env']

        for repo, items in cart_body['repos_items'].iteritems():
            self.add_repo(repo, items)