268 lines
8.3 KiB
Python
268 lines
8.3 KiB
Python
# Copyright 2017 AT&T Intellectual Property. All other rights reserved.
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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 logging
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import traceback
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import falcon
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def get_version_from_request(req):
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"""
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Attempt to extract the api version string
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"""
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for part in req.path.split('/'):
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if '.' in part and part.startswith('v'):
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return part
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return 'N/A'
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# Standard error handler
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def format_error_resp(req,
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resp,
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status_code,
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message="",
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reason="",
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error_type=None,
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retry=False,
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error_list=None,
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info_list=None):
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"""
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Write a error message body and throw a Falcon exception to trigger
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an HTTP status
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:param req: Falcon request object
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:param resp: Falcon response object to update
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:param status_code: Falcon status_code constant
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:param message: Optional error message to include in the body.
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This should be the summary level of the error
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message, encompassing an overall result. If
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no other messages are passed in the error_list,
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this message will be repeated in a generated
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message for the output message_list.
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:param reason: Optional reason code to include in the body
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:param error_type: If specified, the error type will be used,
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otherwise, this will be set to
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'Unspecified Exception'
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:param retry: Optional flag whether client should retry the operation.
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:param error_list: optional list of error dictionaries. Minimally,
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the dictionary will contain the 'message' field,
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but should also contain 'error': True
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:param info_list: optional list of info message dictionaries.
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Minimally, the dictionary needs to contain a
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'message' field, but should also have a
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'error': False field.
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"""
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if error_type is None:
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error_type = 'Unspecified Exception'
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# since we're handling errors here, if error list is none, set
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# up a default error item. If we have info items, add them to the
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# message list as well. In both cases, if the error flag is not
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# set, set it appropriately.
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if error_list is None:
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error_list = [{'message': 'An error occurred, but was not specified',
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'error': True}]
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else:
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for error_item in error_list:
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if 'error' not in error_item:
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error_item['error'] = True
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if info_list is None:
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info_list = []
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else:
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for info_item in info_list:
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if 'error' not in info_item:
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info_item['error'] = False
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message_list = error_list + info_list
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error_response = {
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'kind': 'status',
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'apiVersion': get_version_from_request(req),
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'metadata': {},
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'status': 'Failure',
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'message': message,
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'reason': reason,
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'details': {
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'errorType': error_type,
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'errorCount': len(error_list),
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'messageList': message_list
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},
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'code': status_code,
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'retry': retry
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}
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resp.body = json.dumps(error_response, default=str)
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resp.content_type = 'application/json'
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resp.status = status_code
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def default_error_serializer(req, resp, exception):
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"""
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Writes the default error message body, when we don't handle it otherwise
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"""
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format_error_resp(
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req,
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resp,
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status_code=exception.status,
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message=exception.description,
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reason=exception.title,
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error_type=exception.__class__.__name__,
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error_list=[{'message': exception.description, 'error': True}],
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info_list=None
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)
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def default_exception_handler(ex, req, resp, params):
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"""
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Catch-all exception handler for standardized output.
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If this is a standard falcon HTTPError, rethrow it for handling
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"""
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if isinstance(ex, falcon.HTTPError):
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# allow the falcon http errors to bubble up and get handled
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raise ex
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else:
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# take care of the uncaught stuff
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exc_string = traceback.format_exc()
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logging.error('Unhandled Exception being handled: \n%s', exc_string)
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format_error_resp(
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req,
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resp,
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falcon.HTTP_500,
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error_type=ex.__class__.__name__,
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message="Unhandled Exception raised: %s" % str(ex),
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retry=True
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)
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class AppError(Exception):
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"""
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Base error containing enough information to make a shipyard formatted error
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"""
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title = 'Internal Server Error'
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status = falcon.HTTP_500
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def __init__(self,
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title=None,
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description=None,
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error_list=None,
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info_list=None,
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status=None,
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retry=False,):
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"""
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:param description: The internal error description
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:param error_list: The list of errors
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:param status: The desired falcon HTTP response code
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:param title: The title of the error message
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:param error_list: A list of errors to be included in output
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messages list
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:param info_list: A list of informational messages to be
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included in the output messages list
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:param retry: Optional retry directive for the consumer
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"""
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if title is None:
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self.title = self.__class__.title
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else:
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self.title = title
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if status is None:
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self.status = self.__class__.status
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else:
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self.status = status
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self.description = description
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self.error_list = massage_error_list(error_list, description)
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self.info_list = info_list
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self.retry = retry
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super().__init__(AppError._gen_ex_message(title, description))
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@staticmethod
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def _gen_ex_message(title, description):
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ttl = title or 'Exception'
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dsc = description or 'No additional decsription'
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return '{} : {}'.format(ttl, dsc)
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@staticmethod
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def handle(ex, req, resp, params):
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"""
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The handler used for app errors and child classes
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"""
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format_error_resp(
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req,
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resp,
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ex.status,
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message=ex.title,
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reason=ex.description,
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error_list=ex.error_list,
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info_list=ex.info_list,
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error_type=ex.__class__.__name__,
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retry=ex.retry)
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class AirflowError(AppError):
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"""
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An error to handle errors returned by the Airflow API
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"""
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title = "Error response from Airflow"
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status = falcon.HTTP_400
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class DatabaseError(AppError):
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"""
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An app error specific to database processing.
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"""
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title = 'Database Access Error'
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status = falcon.HTTP_500
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class ApiError(AppError):
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"""
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An error to handle general api errors.
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"""
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title = 'Api Error'
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status = falcon.HTTP_400
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class InvalidFormatError(AppError):
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"""
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An exception to cover invalid input formatting
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"""
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title = 'Validation Failure'
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status = falcon.HTTP_400
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def massage_error_list(error_list, placeholder_description):
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"""
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Returns a best-effort attempt to make a nice error list
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"""
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output_error_list = []
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if error_list:
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for error in error_list:
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if not error.get('message'):
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output_error_list.append({'message': error, 'error': True})
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else:
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if 'error' not in error:
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error['error'] = True
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output_error_list.append(error)
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if not output_error_list:
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output_error_list.append({'message': placeholder_description})
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return output_error_list
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