127 lines
4.5 KiB
Python
127 lines
4.5 KiB
Python
# Copyright 2013 by Rackspace Hosting, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import json
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import sys
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if sys.version_info < (2, 7): # pragma: no cover
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# NOTE(kgriffs): We could use the module from PyPI, but ordering isn't
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# critical in JSON, and Falcon eschews dependencies.
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OrderedDict = dict
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else: # pragma: no cover
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from collections import OrderedDict
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from falcon import util
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class HTTPError(Exception):
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"""Represents a generic HTTP error.
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Raise this or a child class to have Falcon automagically return pretty
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error responses (with an appropriate HTTP status code) to the client
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when something goes wrong.
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Attributes:
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status: HTTP status line, such as "748 Confounded by Ponies".
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title: Error title to send to the client.
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description: Description of the error to send to the client.
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headers: A dictionary of extra headers to add to the response.
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link: An href that the client can provide to the user for getting help.
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code: An internal application code that a user can reference when
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requesting support for the error.
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"""
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__slots__ = (
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'status',
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'title',
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'description',
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'headers',
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'link',
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'code'
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)
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def __init__(self, status, title, description=None, headers=None,
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href=None, href_text=None, code=None):
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"""Initialize with information that can be reported to the client
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Falcon will catch instances of HTTPError (and subclasses), then use
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the associated information to generate a nice response for the client.
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Args:
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status: HTTP status code and text, such as "400 Bad Request"
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title: Human-friendly error title. Set to None if you wish Falcon
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to return an empty response body (all remaining args will
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be ignored except for headers.) Do this only when you don't
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wish to disclose sensitive information about why a request was
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refused, or if the status and headers are self-descriptive.
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description: Human-friendly description of the error, along with a
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helpful suggestion or two (default None).
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headers: A dictionary of extra headers to return in the
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response to the client (default None).
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href: A URL someone can visit to find out more information
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(default None). Unicode characters are percent-encoded.
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href_text: If href is given, use this as the friendly
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title/description for the link (defaults to "API documentation
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for this error").
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code: An internal code that customers can reference in their
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support request or to help them when searching for knowledge
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base articles related to this error.
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"""
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self.status = status
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self.title = title
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self.description = description
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self.headers = headers
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self.code = code
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if href:
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link = self.link = OrderedDict()
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link['text'] = (href_text or 'API documention for this error')
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link['href'] = util.percent_escape(href)
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link['rel'] = 'help'
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else:
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self.link = None
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def json(self):
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"""Returns a pretty JSON-encoded version of the exception
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Note: Excludes the HTTP status line, since the results of this call
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are meant to be returned in the body of an HTTP response.
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Returns:
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A JSON representation of the exception except the status line, or
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NONE if title was set to None.
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"""
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if self.title is None:
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return None
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obj = OrderedDict()
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obj['title'] = self.title
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if self.description:
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obj['description'] = self.description
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if self.code:
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obj['code'] = self.code
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if self.link:
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obj['link'] = self.link
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return json.dumps(obj, indent=4, separators=(',', ': '),
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ensure_ascii=False)
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