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# Copyright 2015 Huawei Technologies Co., Ltd.
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import functools
import inspect
import horizon.exceptions
def handle_errors(error_message, error_default=None, request_arg=None):
"""A decorator for adding default error handling to API calls.
It wraps the original method in a try-except block, with horizon's
error handling added.
Note: it should only be used on functions or methods that take request as
their argument (it has to be named "request", or ``request_arg`` has to be
provided, indicating which argument is the request).
The decorated method accepts a number of additional parameters:
:param _error_handle: whether to handle the errors in this call
:param _error_message: override the error message
:param _error_default: override the default value returned on error
:param _error_redirect: specify a redirect url for errors
:param _error_ignore: ignore known errors
def decorator(func):
if request_arg is None:
_request_arg = 'request'
if _request_arg not in inspect.getfullargspec(func).args:
raise RuntimeError(
"The handle_errors decorator requires 'request' as "
"an argument of the function or method being decorated")
_request_arg = request_arg
def wrapper(*args, **kwargs):
_error_handle = kwargs.pop('_error_handle', True)
_error_message = kwargs.pop('_error_message', error_message)
_error_default = kwargs.pop('_error_default', error_default)
_error_redirect = kwargs.pop('_error_redirect', None)
_error_ignore = kwargs.pop('_error_ignore', False)
if not _error_handle:
return func(*args, **kwargs)
return func(*args, **kwargs)
except Exception as e:
callargs = inspect.getcallargs(func, *args, **kwargs)
request = callargs[_request_arg]
_error_message += ': ' + str(e)
horizon.exceptions.handle(request, _error_message,
return _error_default
wrapper.wrapped = func
return wrapper
return decorator