Files
deb-python-falcon/falcon/exceptions.py
2013-02-11 16:52:26 -05:00

281 lines
9.5 KiB
Python

"""Defines exceptions for gracefully handling various HTTP errors.
Copyright 2013 by Rackspace Hosting, Inc.
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
http://www.apache.org/licenses/LICENSE-2.0
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.
Class docstrings were copied from RFC 2616 where noted, and are not covered
by the above copyright.
"""
from falcon.http_error import HTTPError
import falcon.status_codes as status
class HTTPBadRequest(HTTPError):
"""400 Bad Request
From RFC 2616:
"The request could not be understood by the server due to malformed
syntax. The client SHOULD NOT repeat the request without
modifications."
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_400, title, description, **kwargs)
class HTTPUnauthorized(HTTPError):
"""401 Unauthorized
Use when authentication is required, and the provided credentials are
not valid, or no credentials were provided in the first place.
Args:
title: Human-friendly error title
description: Human-friendly description of the error, along with a
helpful suggestion or two.
scheme: Authentication scheme to use as the value of the
WWW-Authenticate header in the response (default None).
The remaining (optional) args are the same as for HTTPError.
"""
def __init__(self, title, description, scheme=None, **kwargs):
headers = kwargs.setdefault('headers', {})
if scheme is not None:
headers['WWW-Authenticate'] = scheme
HTTPError.__init__(self, status.HTTP_401, title, description, **kwargs)
class HTTPForbidden(HTTPError):
"""403 Forbidden
Use when the client's credentials are good, but they do not have permission
to access the requested resource.
Args:
Same as for HTTPError, except status is set for you.
Note from RFC 2616:
"If the request method was not HEAD and the server wishes to make
public why the request has not been fulfilled, it SHOULD describe the
reason for the refusal in the entity. If the server does not wish to
make this information available to the client, the status code 404
(Not Found) can be used instead."
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_403, title, description, **kwargs)
class HTTPNotFound(HTTPError):
"""404 Not Found
Use this when the URL path does not map to an existing resource, or you
do not wish to disclose exactly why a request was refused.
"""
def __init__(self):
HTTPError.__init__(self, status.HTTP_404, None, None)
class HTTPMethodNotAllowed(HTTPError):
"""405 Method Not Allowed
From RFC 2616:
"The method specified in the Request-Line is not allowed for the
resource identified by the Request-URI. The response MUST include an
Allow header containing a list of valid methods for the requested
resource."
Args:
allowed_methods: A list of allowed HTTP methods for this resource,
such as ['GET', 'POST', 'HEAD'].
The remaining (optional) args are the same as for HTTPError.
"""
def __init__(self, allowed_methods, **kwargs):
headers = kwargs.setdefault('headers', {})
headers['Allow'] = ', '.join(allowed_methods)
HTTPError.__init__(self, status.HTTP_405, None, **kwargs)
class HTTPConflict(HTTPError):
"""409 Conflict
From RFC 2616:
"The request could not be completed due to a conflict with the current
state of the resource. This code is only allowed in situations where
it is expected that the user might be able to resolve the conflict
and resubmit the request. The response body SHOULD include enough
information for the user to recognize the source of the conflict.
Ideally, the response entity would include enough information for the
user or user agent to fix the problem; however, that might not be
possible and is not required."
"Conflicts are most likely to occur in response to a PUT request. For
example, if versioning were being used and the entity being PUT
included changes to a resource which conflict with those made by an
earlier (third-party) request, the server might use the 409 response
to indicate that it can't complete the request. In this case, the
response entity would likely contain a list of the differences
between the two versions in a format defined by the response
Content-Type."
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_409, title, description, **kwargs)
class HTTPPreconditionFailed(HTTPError):
"""412 Precondition Failed
From RFC 2616:
"The precondition given in one or more of the request-header fields
evaluated to false when it was tested on the server. This response
code allows the client to place preconditions on the current resource
metainformation (header field data) and thus prevent the requested
method from being applied to a resource other than the one intended."
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_412, title, description, **kwargs)
class HTTPUnsupportedMediaType(HTTPError):
"""415 Unsupported Media Type
Sets title to "Unsupported media type".
Args:
description: Human-friendly description of the error, along with a
helpful suggestion or two.
The remaining (optional) args are the same as for HTTPError.
"""
def __init__(self, description, **kwargs):
HTTPError.__init__(self, status.HTTP_415, 'Unsupported media type',
description, **kwargs)
class HTTPRangeNotSatisfiable(HTTPError):
"""416 Range Not Satisfiable
See also: http://goo.gl/yvh9H
Args:
resource_length: The maximum value for the last-byte-pos of a range
request. Used to set the Content-Range header.
media_type: Media type to use as the value of the Content-Type
header, or None to use the default passed to the API initializer.
"""
def __init__(self, resource_length, media_type=None):
headers = {'Content-Range': 'bytes */' + str(resource_length)}
if media_type is not None:
headers['Content-Type'] = media_type
HTTPError.__init__(self, status.HTTP_416, None, None, headers=headers)
class HTTPUpgradeRequired(HTTPError):
"""426 Upgrade Required
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_426, title, description, **kwargs)
class HTTPInternalServerError(HTTPError):
"""500 Internal Server Error
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_500, title, description, **kwargs)
class HTTPBadGateway(HTTPError):
"""502 Bad Gateway
Args:
Same as for HTTPError, except status is set for you.
"""
def __init__(self, title, description, **kwargs):
HTTPError.__init__(self, status.HTTP_502, title, description, **kwargs)
class HTTPServiceUnavailable(HTTPError):
"""503 Service Unavailable
Args:
title: Human-friendly error title. Set to None if you wish Falcon
to return an empty response body (all remaining args will
be ignored except for headers.) Do this only when you don't
wish to disclose sensitive information about why a request was
refused, or if the status and headers are self-descriptive.
description: Human-friendly description of the error, along with a
helpful suggestion or two (default None).
retry_after: Value for the Retry-After header. If a date object, will
serialize as an HTTP date. Otherwise, a non-negative int is
expected, representing the number of seconds to wait. See
also: http://goo.gl/DIrWr
headers: A dictionary of extra headers to return in the
response to the client (default None).
href: A URL someone can visit to find out more information
(default None).
href_rel: If href is given, use this value for the rel
attribute (default 'doc').
href_text: If href is given, use this as the friendly
title/description for the link (defaults to "API documentation
for this error").
code: An internal code that customers can reference in their
support request or to help them when searching for knowledge
base articles related to this error.
"""
def __init__(self, title, description, retry_after, **kwargs):
headers = kwargs.setdefault('headers', {})
headers['Retry-After'] = str(retry_after)
HTTPError.__init__(self, status.HTTP_503, title, description, **kwargs)