385 lines
11 KiB
Python
385 lines
11 KiB
Python
"""
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Sanic `provides a pattern
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<https://sanicframework.org/guide/best-practices/exceptions.html#using-sanic-exceptions>`_
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for providing a response when an exception occurs. However, if you do no handle
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an exception, it will provide a fallback. There are three fallback types:
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- HTML - *default*
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- Text
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- JSON
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Setting ``app.config.FALLBACK_ERROR_FORMAT = "auto"`` will enable a switch that
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will attempt to provide an appropriate response format based upon the
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request type.
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"""
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from __future__ import annotations
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import sys
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import typing as t
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from functools import partial
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from traceback import extract_tb
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from sanic.exceptions import BadRequest, SanicException
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from sanic.helpers import STATUS_CODES
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from sanic.log import deprecation, logger
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from sanic.pages.error import ErrorPage
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from sanic.response import html, json, text
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dumps: t.Callable[..., str]
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try:
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from ujson import dumps
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dumps = partial(dumps, escape_forward_slashes=False)
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except ImportError: # noqa
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from json import dumps
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if t.TYPE_CHECKING:
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from sanic import HTTPResponse, Request
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DEFAULT_FORMAT = "auto"
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FALLBACK_TEXT = """\
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The application encountered an unexpected error and could not continue.\
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"""
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FALLBACK_STATUS = 500
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JSON = "application/json"
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class BaseRenderer:
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"""
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Base class that all renderers must inherit from.
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"""
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dumps = staticmethod(dumps)
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def __init__(self, request, exception, debug):
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self.request = request
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self.exception = exception
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self.debug = debug
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@property
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def headers(self):
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if isinstance(self.exception, SanicException):
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return getattr(self.exception, "headers", {})
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return {}
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@property
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def status(self):
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if isinstance(self.exception, SanicException):
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return getattr(self.exception, "status_code", FALLBACK_STATUS)
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return FALLBACK_STATUS
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@property
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def text(self):
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if self.debug or isinstance(self.exception, SanicException):
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return str(self.exception)
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return FALLBACK_TEXT
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@property
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def title(self):
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status_text = STATUS_CODES.get(self.status, b"Error Occurred").decode()
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return f"{self.status} — {status_text}"
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def render(self) -> HTTPResponse:
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"""
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Outputs the exception as a :class:`HTTPResponse`.
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:return: The formatted exception
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:rtype: str
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"""
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output = (
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self.full
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if self.debug and not getattr(self.exception, "quiet", False)
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else self.minimal
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)()
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output.status = self.status
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output.headers.update(self.headers)
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return output
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def minimal(self) -> HTTPResponse: # noqa
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"""
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Provide a formatted message that is meant to not show any sensitive
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data or details.
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"""
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raise NotImplementedError
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def full(self) -> HTTPResponse: # noqa
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"""
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Provide a formatted message that has all details and is mean to be used
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primarily for debugging and non-production environments.
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"""
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raise NotImplementedError
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class HTMLRenderer(BaseRenderer):
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"""
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Render an exception as HTML.
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The default fallback type.
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"""
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def full(self) -> HTTPResponse:
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page = ErrorPage(
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debug=self.debug,
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title=super().title,
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text=super().text,
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request=self.request,
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exc=self.exception,
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)
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return html(page.render())
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def minimal(self) -> HTTPResponse:
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return self.full()
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class TextRenderer(BaseRenderer):
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"""
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Render an exception as plain text.
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"""
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OUTPUT_TEXT = "{title}\n{bar}\n{text}\n\n{body}"
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SPACER = " "
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def full(self) -> HTTPResponse:
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return text(
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self.OUTPUT_TEXT.format(
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title=self.title,
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text=self.text,
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bar=("=" * len(self.title)),
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body=self._generate_body(full=True),
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)
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)
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def minimal(self) -> HTTPResponse:
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return text(
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self.OUTPUT_TEXT.format(
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title=self.title,
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text=self.text,
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bar=("=" * len(self.title)),
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body=self._generate_body(full=False),
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)
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)
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@property
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def title(self):
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return f"⚠️ {super().title}"
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def _generate_body(self, *, full):
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lines = []
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if full:
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_, exc_value, __ = sys.exc_info()
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exceptions = []
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lines += [
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f"{self.exception.__class__.__name__}: {self.exception} while "
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f"handling path {self.request.path}",
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f"Traceback of {self.request.app.name} "
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"(most recent call last):\n",
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]
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while exc_value:
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exceptions.append(self._format_exc(exc_value))
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exc_value = exc_value.__cause__
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lines += exceptions[::-1]
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for attr, display in (("context", True), ("extra", bool(full))):
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info = getattr(self.exception, attr, None)
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if info and display:
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lines += self._generate_object_display_list(info, attr)
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return "\n".join(lines)
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def _format_exc(self, exc):
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frames = "\n\n".join(
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[
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f"{self.SPACER * 2}File {frame.filename}, "
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f"line {frame.lineno}, in "
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f"{frame.name}\n{self.SPACER * 2}{frame.line}"
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for frame in extract_tb(exc.__traceback__)
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]
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)
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return f"{self.SPACER}{exc.__class__.__name__}: {exc}\n{frames}"
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def _generate_object_display_list(self, obj, descriptor):
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lines = [f"\n{descriptor.title()}"]
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for key, value in obj.items():
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display = self.dumps(value)
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lines.append(f"{self.SPACER * 2}{key}: {display}")
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return lines
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class JSONRenderer(BaseRenderer):
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"""
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Render an exception as JSON.
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"""
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def full(self) -> HTTPResponse:
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output = self._generate_output(full=True)
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return json(output, dumps=self.dumps)
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def minimal(self) -> HTTPResponse:
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output = self._generate_output(full=False)
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return json(output, dumps=self.dumps)
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def _generate_output(self, *, full):
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output = {
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"description": self.title,
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"status": self.status,
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"message": self.text,
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}
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for attr, display in (("context", True), ("extra", bool(full))):
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info = getattr(self.exception, attr, None)
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if info and display:
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output[attr] = info
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if full:
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_, exc_value, __ = sys.exc_info()
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exceptions = []
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while exc_value:
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exceptions.append(
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{
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"type": exc_value.__class__.__name__,
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"exception": str(exc_value),
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"frames": [
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{
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"file": frame.filename,
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"line": frame.lineno,
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"name": frame.name,
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"src": frame.line,
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}
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for frame in extract_tb(exc_value.__traceback__)
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],
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}
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)
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exc_value = exc_value.__cause__
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output["path"] = self.request.path
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output["args"] = self.request.args
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output["exceptions"] = exceptions[::-1]
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return output
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@property
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def title(self):
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return STATUS_CODES.get(self.status, b"Error Occurred").decode()
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def escape(text):
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"""
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Minimal HTML escaping, not for attribute values (unlike html.escape).
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"""
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return f"{text}".replace("&", "&").replace("<", "<")
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MIME_BY_CONFIG = {
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"text": "text/plain",
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"json": "application/json",
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"html": "text/html",
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}
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CONFIG_BY_MIME = {v: k for k, v in MIME_BY_CONFIG.items()}
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RENDERERS_BY_CONTENT_TYPE = {
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"text/plain": TextRenderer,
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"application/json": JSONRenderer,
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"multipart/form-data": HTMLRenderer,
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"text/html": HTMLRenderer,
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}
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# Handler source code is checked for which response types it returns with the
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# route error_format="auto" (default) to determine which format to use.
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RESPONSE_MAPPING = {
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"json": "json",
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"text": "text",
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"html": "html",
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"JSONResponse": "json",
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"text/plain": "text",
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"text/html": "html",
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"application/json": "json",
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}
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def check_error_format(format):
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if format not in MIME_BY_CONFIG and format != "auto":
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raise SanicException(f"Unknown format: {format}")
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def exception_response(
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request: Request,
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exception: Exception,
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debug: bool,
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fallback: str,
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base: t.Type[BaseRenderer],
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renderer: t.Type[t.Optional[BaseRenderer]] = None,
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) -> HTTPResponse:
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"""
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Render a response for the default FALLBACK exception handler.
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"""
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if not renderer:
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mt = guess_mime(request, fallback)
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renderer = RENDERERS_BY_CONTENT_TYPE.get(mt, base)
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renderer = t.cast(t.Type[BaseRenderer], renderer)
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return renderer(request, exception, debug).render()
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def guess_mime(req: Request, fallback: str) -> str:
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# Attempt to find a suitable MIME format for the response.
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# Insertion-ordered map of formats["html"] = "source of that suggestion"
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formats = {}
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name = ""
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# Route error_format (by magic from handler code if auto, the default)
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if req.route:
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name = req.route.name
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f = req.route.extra.error_format
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if f in MIME_BY_CONFIG:
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formats[f] = name
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if not formats and fallback in MIME_BY_CONFIG:
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formats[fallback] = "FALLBACK_ERROR_FORMAT"
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# If still not known, check for the request for clues of JSON
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if not formats and fallback == "auto" and req.accept.match(JSON):
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if JSON in req.accept: # Literally, not wildcard
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formats["json"] = "request.accept"
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elif JSON in req.headers.getone("content-type", ""):
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formats["json"] = "content-type"
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# DEPRECATION: Remove this block in 24.3
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else:
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c = None
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try:
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c = req.json
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except BadRequest:
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pass
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if c:
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formats["json"] = "request.json"
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deprecation(
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"Response type was determined by the JSON content of "
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"the request. This behavior is deprecated and will be "
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"removed in v24.3. Please specify the format either by\n"
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f' error_format="json" on route {name}, by\n'
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' FALLBACK_ERROR_FORMAT = "json", or by adding header\n'
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" accept: application/json to your requests.",
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24.3,
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)
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# Any other supported formats
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if fallback == "auto":
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for k in MIME_BY_CONFIG:
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if k not in formats:
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formats[k] = "any"
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mimes = [MIME_BY_CONFIG[k] for k in formats]
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m = req.accept.match(*mimes)
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if m:
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format = CONFIG_BY_MIME[m.mime]
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source = formats[format]
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logger.debug(
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f"The client accepts {m.header}, using '{format}' from {source}"
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)
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else:
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logger.debug(f"No format found, the client accepts {req.accept!r}")
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return m.mime
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