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- """Implements a number of Python exceptions which can be raised from within
- a view to trigger a standard HTTP non-200 response.
- Usage Example
- -------------
- .. code-block:: python
- from werkzeug.wrappers.request import Request
- from werkzeug.exceptions import HTTPException, NotFound
- def view(request):
- raise NotFound()
- @Request.application
- def application(request):
- try:
- return view(request)
- except HTTPException as e:
- return e
- As you can see from this example those exceptions are callable WSGI
- applications. However, they are not Werkzeug response objects. You
- can get a response object by calling ``get_response()`` on a HTTP
- exception.
- Keep in mind that you may have to pass an environ (WSGI) or scope
- (ASGI) to ``get_response()`` because some errors fetch additional
- information relating to the request.
- If you want to hook in a different exception page to say, a 404 status
- code, you can add a second except for a specific subclass of an error:
- .. code-block:: python
- @Request.application
- def application(request):
- try:
- return view(request)
- except NotFound as e:
- return not_found(request)
- except HTTPException as e:
- return e
- """
- import typing as t
- from datetime import datetime
- from html import escape
- from ._internal import _get_environ
- if t.TYPE_CHECKING:
- import typing_extensions as te
- from _typeshed.wsgi import StartResponse
- from _typeshed.wsgi import WSGIEnvironment
- from .datastructures import WWWAuthenticate
- from .sansio.response import Response
- from .wrappers.request import Request as WSGIRequest # noqa: F401
- from .wrappers.response import Response as WSGIResponse # noqa: F401
- class HTTPException(Exception):
- """The base class for all HTTP exceptions. This exception can be called as a WSGI
- application to render a default error page or you can catch the subclasses
- of it independently and render nicer error messages.
- .. versionchanged:: 2.1
- Removed the ``wrap`` class method.
- """
- code: t.Optional[int] = None
- description: t.Optional[str] = None
- def __init__(
- self,
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- ) -> None:
- super().__init__()
- if description is not None:
- self.description = description
- self.response = response
- @property
- def name(self) -> str:
- """The status name."""
- from .http import HTTP_STATUS_CODES
- return HTTP_STATUS_CODES.get(self.code, "Unknown Error") # type: ignore
- def get_description(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> str:
- """Get the description."""
- if self.description is None:
- description = ""
- elif not isinstance(self.description, str):
- description = str(self.description)
- else:
- description = self.description
- description = escape(description).replace("\n", "<br>")
- return f"<p>{description}</p>"
- def get_body(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> str:
- """Get the HTML body."""
- return (
- "<!doctype html>\n"
- "<html lang=en>\n"
- f"<title>{self.code} {escape(self.name)}</title>\n"
- f"<h1>{escape(self.name)}</h1>\n"
- f"{self.get_description(environ)}\n"
- )
- def get_headers(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> t.List[t.Tuple[str, str]]:
- """Get a list of headers."""
- return [("Content-Type", "text/html; charset=utf-8")]
- def get_response(
- self,
- environ: t.Optional[t.Union["WSGIEnvironment", "WSGIRequest"]] = None,
- scope: t.Optional[dict] = None,
- ) -> "Response":
- """Get a response object. If one was passed to the exception
- it's returned directly.
- :param environ: the optional environ for the request. This
- can be used to modify the response depending
- on how the request looked like.
- :return: a :class:`Response` object or a subclass thereof.
- """
- from .wrappers.response import Response as WSGIResponse # noqa: F811
- if self.response is not None:
- return self.response
- if environ is not None:
- environ = _get_environ(environ)
- headers = self.get_headers(environ, scope)
- return WSGIResponse(self.get_body(environ, scope), self.code, headers)
- def __call__(
- self, environ: "WSGIEnvironment", start_response: "StartResponse"
- ) -> t.Iterable[bytes]:
- """Call the exception as WSGI application.
- :param environ: the WSGI environment.
- :param start_response: the response callable provided by the WSGI
- server.
- """
- response = t.cast("WSGIResponse", self.get_response(environ))
- return response(environ, start_response)
- def __str__(self) -> str:
- code = self.code if self.code is not None else "???"
- return f"{code} {self.name}: {self.description}"
- def __repr__(self) -> str:
- code = self.code if self.code is not None else "???"
- return f"<{type(self).__name__} '{code}: {self.name}'>"
- class BadRequest(HTTPException):
- """*400* `Bad Request`
- Raise if the browser sends something to the application the application
- or server cannot handle.
- """
- code = 400
- description = (
- "The browser (or proxy) sent a request that this server could "
- "not understand."
- )
- class BadRequestKeyError(BadRequest, KeyError):
- """An exception that is used to signal both a :exc:`KeyError` and a
- :exc:`BadRequest`. Used by many of the datastructures.
- """
- _description = BadRequest.description
- #: Show the KeyError along with the HTTP error message in the
- #: response. This should be disabled in production, but can be
- #: useful in a debug mode.
- show_exception = False
- def __init__(self, arg: t.Optional[str] = None, *args: t.Any, **kwargs: t.Any):
- super().__init__(*args, **kwargs)
- if arg is None:
- KeyError.__init__(self)
- else:
- KeyError.__init__(self, arg)
- @property # type: ignore
- def description(self) -> str: # type: ignore
- if self.show_exception:
- return (
- f"{self._description}\n"
- f"{KeyError.__name__}: {KeyError.__str__(self)}"
- )
- return self._description
- @description.setter
- def description(self, value: str) -> None:
- self._description = value
- class ClientDisconnected(BadRequest):
- """Internal exception that is raised if Werkzeug detects a disconnected
- client. Since the client is already gone at that point attempting to
- send the error message to the client might not work and might ultimately
- result in another exception in the server. Mainly this is here so that
- it is silenced by default as far as Werkzeug is concerned.
- Since disconnections cannot be reliably detected and are unspecified
- by WSGI to a large extent this might or might not be raised if a client
- is gone.
- .. versionadded:: 0.8
- """
- class SecurityError(BadRequest):
- """Raised if something triggers a security error. This is otherwise
- exactly like a bad request error.
- .. versionadded:: 0.9
- """
- class BadHost(BadRequest):
- """Raised if the submitted host is badly formatted.
- .. versionadded:: 0.11.2
- """
- class Unauthorized(HTTPException):
- """*401* ``Unauthorized``
- Raise if the user is not authorized to access a resource.
- The ``www_authenticate`` argument should be used to set the
- ``WWW-Authenticate`` header. This is used for HTTP basic auth and
- other schemes. Use :class:`~werkzeug.datastructures.WWWAuthenticate`
- to create correctly formatted values. Strictly speaking a 401
- response is invalid if it doesn't provide at least one value for
- this header, although real clients typically don't care.
- :param description: Override the default message used for the body
- of the response.
- :param www-authenticate: A single value, or list of values, for the
- WWW-Authenticate header(s).
- .. versionchanged:: 2.0
- Serialize multiple ``www_authenticate`` items into multiple
- ``WWW-Authenticate`` headers, rather than joining them
- into a single value, for better interoperability.
- .. versionchanged:: 0.15.3
- If the ``www_authenticate`` argument is not set, the
- ``WWW-Authenticate`` header is not set.
- .. versionchanged:: 0.15.3
- The ``response`` argument was restored.
- .. versionchanged:: 0.15.1
- ``description`` was moved back as the first argument, restoring
- its previous position.
- .. versionchanged:: 0.15.0
- ``www_authenticate`` was added as the first argument, ahead of
- ``description``.
- """
- code = 401
- description = (
- "The server could not verify that you are authorized to access"
- " the URL requested. You either supplied the wrong credentials"
- " (e.g. a bad password), or your browser doesn't understand"
- " how to supply the credentials required."
- )
- def __init__(
- self,
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- www_authenticate: t.Optional[
- t.Union["WWWAuthenticate", t.Iterable["WWWAuthenticate"]]
- ] = None,
- ) -> None:
- super().__init__(description, response)
- from .datastructures import WWWAuthenticate
- if isinstance(www_authenticate, WWWAuthenticate):
- www_authenticate = (www_authenticate,)
- self.www_authenticate = www_authenticate
- def get_headers(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> t.List[t.Tuple[str, str]]:
- headers = super().get_headers(environ, scope)
- if self.www_authenticate:
- headers.extend(("WWW-Authenticate", str(x)) for x in self.www_authenticate)
- return headers
- class Forbidden(HTTPException):
- """*403* `Forbidden`
- Raise if the user doesn't have the permission for the requested resource
- but was authenticated.
- """
- code = 403
- description = (
- "You don't have the permission to access the requested"
- " resource. It is either read-protected or not readable by the"
- " server."
- )
- class NotFound(HTTPException):
- """*404* `Not Found`
- Raise if a resource does not exist and never existed.
- """
- code = 404
- description = (
- "The requested URL was not found on the server. If you entered"
- " the URL manually please check your spelling and try again."
- )
- class MethodNotAllowed(HTTPException):
- """*405* `Method Not Allowed`
- Raise if the server used a method the resource does not handle. For
- example `POST` if the resource is view only. Especially useful for REST.
- The first argument for this exception should be a list of allowed methods.
- Strictly speaking the response would be invalid if you don't provide valid
- methods in the header which you can do with that list.
- """
- code = 405
- description = "The method is not allowed for the requested URL."
- def __init__(
- self,
- valid_methods: t.Optional[t.Iterable[str]] = None,
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- ) -> None:
- """Takes an optional list of valid http methods
- starting with werkzeug 0.3 the list will be mandatory."""
- super().__init__(description=description, response=response)
- self.valid_methods = valid_methods
- def get_headers(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> t.List[t.Tuple[str, str]]:
- headers = super().get_headers(environ, scope)
- if self.valid_methods:
- headers.append(("Allow", ", ".join(self.valid_methods)))
- return headers
- class NotAcceptable(HTTPException):
- """*406* `Not Acceptable`
- Raise if the server can't return any content conforming to the
- `Accept` headers of the client.
- """
- code = 406
- description = (
- "The resource identified by the request is only capable of"
- " generating response entities which have content"
- " characteristics not acceptable according to the accept"
- " headers sent in the request."
- )
- class RequestTimeout(HTTPException):
- """*408* `Request Timeout`
- Raise to signalize a timeout.
- """
- code = 408
- description = (
- "The server closed the network connection because the browser"
- " didn't finish the request within the specified time."
- )
- class Conflict(HTTPException):
- """*409* `Conflict`
- Raise to signal that a request cannot be completed because it conflicts
- with the current state on the server.
- .. versionadded:: 0.7
- """
- code = 409
- description = (
- "A conflict happened while processing the request. The"
- " resource might have been modified while the request was being"
- " processed."
- )
- class Gone(HTTPException):
- """*410* `Gone`
- Raise if a resource existed previously and went away without new location.
- """
- code = 410
- description = (
- "The requested URL is no longer available on this server and"
- " there is no forwarding address. If you followed a link from a"
- " foreign page, please contact the author of this page."
- )
- class LengthRequired(HTTPException):
- """*411* `Length Required`
- Raise if the browser submitted data but no ``Content-Length`` header which
- is required for the kind of processing the server does.
- """
- code = 411
- description = (
- "A request with this method requires a valid <code>Content-"
- "Length</code> header."
- )
- class PreconditionFailed(HTTPException):
- """*412* `Precondition Failed`
- Status code used in combination with ``If-Match``, ``If-None-Match``, or
- ``If-Unmodified-Since``.
- """
- code = 412
- description = (
- "The precondition on the request for the URL failed positive evaluation."
- )
- class RequestEntityTooLarge(HTTPException):
- """*413* `Request Entity Too Large`
- The status code one should return if the data submitted exceeded a given
- limit.
- """
- code = 413
- description = "The data value transmitted exceeds the capacity limit."
- class RequestURITooLarge(HTTPException):
- """*414* `Request URI Too Large`
- Like *413* but for too long URLs.
- """
- code = 414
- description = (
- "The length of the requested URL exceeds the capacity limit for"
- " this server. The request cannot be processed."
- )
- class UnsupportedMediaType(HTTPException):
- """*415* `Unsupported Media Type`
- The status code returned if the server is unable to handle the media type
- the client transmitted.
- """
- code = 415
- description = (
- "The server does not support the media type transmitted in the request."
- )
- class RequestedRangeNotSatisfiable(HTTPException):
- """*416* `Requested Range Not Satisfiable`
- The client asked for an invalid part of the file.
- .. versionadded:: 0.7
- """
- code = 416
- description = "The server cannot provide the requested range."
- def __init__(
- self,
- length: t.Optional[int] = None,
- units: str = "bytes",
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- ) -> None:
- """Takes an optional `Content-Range` header value based on ``length``
- parameter.
- """
- super().__init__(description=description, response=response)
- self.length = length
- self.units = units
- def get_headers(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> t.List[t.Tuple[str, str]]:
- headers = super().get_headers(environ, scope)
- if self.length is not None:
- headers.append(("Content-Range", f"{self.units} */{self.length}"))
- return headers
- class ExpectationFailed(HTTPException):
- """*417* `Expectation Failed`
- The server cannot meet the requirements of the Expect request-header.
- .. versionadded:: 0.7
- """
- code = 417
- description = "The server could not meet the requirements of the Expect header"
- class ImATeapot(HTTPException):
- """*418* `I'm a teapot`
- The server should return this if it is a teapot and someone attempted
- to brew coffee with it.
- .. versionadded:: 0.7
- """
- code = 418
- description = "This server is a teapot, not a coffee machine"
- class UnprocessableEntity(HTTPException):
- """*422* `Unprocessable Entity`
- Used if the request is well formed, but the instructions are otherwise
- incorrect.
- """
- code = 422
- description = (
- "The request was well-formed but was unable to be followed due"
- " to semantic errors."
- )
- class Locked(HTTPException):
- """*423* `Locked`
- Used if the resource that is being accessed is locked.
- """
- code = 423
- description = "The resource that is being accessed is locked."
- class FailedDependency(HTTPException):
- """*424* `Failed Dependency`
- Used if the method could not be performed on the resource
- because the requested action depended on another action and that action failed.
- """
- code = 424
- description = (
- "The method could not be performed on the resource because the"
- " requested action depended on another action and that action"
- " failed."
- )
- class PreconditionRequired(HTTPException):
- """*428* `Precondition Required`
- The server requires this request to be conditional, typically to prevent
- the lost update problem, which is a race condition between two or more
- clients attempting to update a resource through PUT or DELETE. By requiring
- each client to include a conditional header ("If-Match" or "If-Unmodified-
- Since") with the proper value retained from a recent GET request, the
- server ensures that each client has at least seen the previous revision of
- the resource.
- """
- code = 428
- description = (
- "This request is required to be conditional; try using"
- ' "If-Match" or "If-Unmodified-Since".'
- )
- class _RetryAfter(HTTPException):
- """Adds an optional ``retry_after`` parameter which will set the
- ``Retry-After`` header. May be an :class:`int` number of seconds or
- a :class:`~datetime.datetime`.
- """
- def __init__(
- self,
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- retry_after: t.Optional[t.Union[datetime, int]] = None,
- ) -> None:
- super().__init__(description, response)
- self.retry_after = retry_after
- def get_headers(
- self,
- environ: t.Optional["WSGIEnvironment"] = None,
- scope: t.Optional[dict] = None,
- ) -> t.List[t.Tuple[str, str]]:
- headers = super().get_headers(environ, scope)
- if self.retry_after:
- if isinstance(self.retry_after, datetime):
- from .http import http_date
- value = http_date(self.retry_after)
- else:
- value = str(self.retry_after)
- headers.append(("Retry-After", value))
- return headers
- class TooManyRequests(_RetryAfter):
- """*429* `Too Many Requests`
- The server is limiting the rate at which this user receives
- responses, and this request exceeds that rate. (The server may use
- any convenient method to identify users and their request rates).
- The server may include a "Retry-After" header to indicate how long
- the user should wait before retrying.
- :param retry_after: If given, set the ``Retry-After`` header to this
- value. May be an :class:`int` number of seconds or a
- :class:`~datetime.datetime`.
- .. versionchanged:: 1.0
- Added ``retry_after`` parameter.
- """
- code = 429
- description = "This user has exceeded an allotted request count. Try again later."
- class RequestHeaderFieldsTooLarge(HTTPException):
- """*431* `Request Header Fields Too Large`
- The server refuses to process the request because the header fields are too
- large. One or more individual fields may be too large, or the set of all
- headers is too large.
- """
- code = 431
- description = "One or more header fields exceeds the maximum size."
- class UnavailableForLegalReasons(HTTPException):
- """*451* `Unavailable For Legal Reasons`
- This status code indicates that the server is denying access to the
- resource as a consequence of a legal demand.
- """
- code = 451
- description = "Unavailable for legal reasons."
- class InternalServerError(HTTPException):
- """*500* `Internal Server Error`
- Raise if an internal server error occurred. This is a good fallback if an
- unknown error occurred in the dispatcher.
- .. versionchanged:: 1.0.0
- Added the :attr:`original_exception` attribute.
- """
- code = 500
- description = (
- "The server encountered an internal error and was unable to"
- " complete your request. Either the server is overloaded or"
- " there is an error in the application."
- )
- def __init__(
- self,
- description: t.Optional[str] = None,
- response: t.Optional["Response"] = None,
- original_exception: t.Optional[BaseException] = None,
- ) -> None:
- #: The original exception that caused this 500 error. Can be
- #: used by frameworks to provide context when handling
- #: unexpected errors.
- self.original_exception = original_exception
- super().__init__(description=description, response=response)
- class NotImplemented(HTTPException):
- """*501* `Not Implemented`
- Raise if the application does not support the action requested by the
- browser.
- """
- code = 501
- description = "The server does not support the action requested by the browser."
- class BadGateway(HTTPException):
- """*502* `Bad Gateway`
- If you do proxying in your application you should return this status code
- if you received an invalid response from the upstream server it accessed
- in attempting to fulfill the request.
- """
- code = 502
- description = (
- "The proxy server received an invalid response from an upstream server."
- )
- class ServiceUnavailable(_RetryAfter):
- """*503* `Service Unavailable`
- Status code you should return if a service is temporarily
- unavailable.
- :param retry_after: If given, set the ``Retry-After`` header to this
- value. May be an :class:`int` number of seconds or a
- :class:`~datetime.datetime`.
- .. versionchanged:: 1.0
- Added ``retry_after`` parameter.
- """
- code = 503
- description = (
- "The server is temporarily unable to service your request due"
- " to maintenance downtime or capacity problems. Please try"
- " again later."
- )
- class GatewayTimeout(HTTPException):
- """*504* `Gateway Timeout`
- Status code you should return if a connection to an upstream server
- times out.
- """
- code = 504
- description = "The connection to an upstream server timed out."
- class HTTPVersionNotSupported(HTTPException):
- """*505* `HTTP Version Not Supported`
- The server does not support the HTTP protocol version used in the request.
- """
- code = 505
- description = (
- "The server does not support the HTTP protocol version used in the request."
- )
- default_exceptions: t.Dict[int, t.Type[HTTPException]] = {}
- def _find_exceptions() -> None:
- for obj in globals().values():
- try:
- is_http_exception = issubclass(obj, HTTPException)
- except TypeError:
- is_http_exception = False
- if not is_http_exception or obj.code is None:
- continue
- old_obj = default_exceptions.get(obj.code, None)
- if old_obj is not None and issubclass(obj, old_obj):
- continue
- default_exceptions[obj.code] = obj
- _find_exceptions()
- del _find_exceptions
- class Aborter:
- """When passed a dict of code -> exception items it can be used as
- callable that raises exceptions. If the first argument to the
- callable is an integer it will be looked up in the mapping, if it's
- a WSGI application it will be raised in a proxy exception.
- The rest of the arguments are forwarded to the exception constructor.
- """
- def __init__(
- self,
- mapping: t.Optional[t.Dict[int, t.Type[HTTPException]]] = None,
- extra: t.Optional[t.Dict[int, t.Type[HTTPException]]] = None,
- ) -> None:
- if mapping is None:
- mapping = default_exceptions
- self.mapping = dict(mapping)
- if extra is not None:
- self.mapping.update(extra)
- def __call__(
- self, code: t.Union[int, "Response"], *args: t.Any, **kwargs: t.Any
- ) -> "te.NoReturn":
- from .sansio.response import Response
- if isinstance(code, Response):
- raise HTTPException(response=code)
- if code not in self.mapping:
- raise LookupError(f"no exception for {code!r}")
- raise self.mapping[code](*args, **kwargs)
- def abort(
- status: t.Union[int, "Response"], *args: t.Any, **kwargs: t.Any
- ) -> "te.NoReturn":
- """Raises an :py:exc:`HTTPException` for the given status code or WSGI
- application.
- If a status code is given, it will be looked up in the list of
- exceptions and will raise that exception. If passed a WSGI application,
- it will wrap it in a proxy WSGI exception and raise that::
- abort(404) # 404 Not Found
- abort(Response('Hello World'))
- """
- _aborter(status, *args, **kwargs)
- _aborter: Aborter = Aborter()
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