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- import typing as t
- from .app import Flask
- from .blueprints import Blueprint
- from .globals import request_ctx
- class UnexpectedUnicodeError(AssertionError, UnicodeError):
- """Raised in places where we want some better error reporting for
- unexpected unicode or binary data.
- """
- class DebugFilesKeyError(KeyError, AssertionError):
- """Raised from request.files during debugging. The idea is that it can
- provide a better error message than just a generic KeyError/BadRequest.
- """
- def __init__(self, request, key):
- form_matches = request.form.getlist(key)
- buf = [
- f"You tried to access the file {key!r} in the request.files"
- " dictionary but it does not exist. The mimetype for the"
- f" request is {request.mimetype!r} instead of"
- " 'multipart/form-data' which means that no file contents"
- " were transmitted. To fix this error you should provide"
- ' enctype="multipart/form-data" in your form.'
- ]
- if form_matches:
- names = ", ".join(repr(x) for x in form_matches)
- buf.append(
- "\n\nThe browser instead transmitted some file names. "
- f"This was submitted: {names}"
- )
- self.msg = "".join(buf)
- def __str__(self):
- return self.msg
- class FormDataRoutingRedirect(AssertionError):
- """This exception is raised in debug mode if a routing redirect
- would cause the browser to drop the method or body. This happens
- when method is not GET, HEAD or OPTIONS and the status code is not
- 307 or 308.
- """
- def __init__(self, request):
- exc = request.routing_exception
- buf = [
- f"A request was sent to '{request.url}', but routing issued"
- f" a redirect to the canonical URL '{exc.new_url}'."
- ]
- if f"{request.base_url}/" == exc.new_url.partition("?")[0]:
- buf.append(
- " The URL was defined with a trailing slash. Flask"
- " will redirect to the URL with a trailing slash if it"
- " was accessed without one."
- )
- buf.append(
- " Send requests to the canonical URL, or use 307 or 308 for"
- " routing redirects. Otherwise, browsers will drop form"
- " data.\n\n"
- "This exception is only raised in debug mode."
- )
- super().__init__("".join(buf))
- def attach_enctype_error_multidict(request):
- """Patch ``request.files.__getitem__`` to raise a descriptive error
- about ``enctype=multipart/form-data``.
- :param request: The request to patch.
- :meta private:
- """
- oldcls = request.files.__class__
- class newcls(oldcls):
- def __getitem__(self, key):
- try:
- return super().__getitem__(key)
- except KeyError as e:
- if key not in request.form:
- raise
- raise DebugFilesKeyError(request, key).with_traceback(
- e.__traceback__
- ) from None
- newcls.__name__ = oldcls.__name__
- newcls.__module__ = oldcls.__module__
- request.files.__class__ = newcls
- def _dump_loader_info(loader) -> t.Generator:
- yield f"class: {type(loader).__module__}.{type(loader).__name__}"
- for key, value in sorted(loader.__dict__.items()):
- if key.startswith("_"):
- continue
- if isinstance(value, (tuple, list)):
- if not all(isinstance(x, str) for x in value):
- continue
- yield f"{key}:"
- for item in value:
- yield f" - {item}"
- continue
- elif not isinstance(value, (str, int, float, bool)):
- continue
- yield f"{key}: {value!r}"
- def explain_template_loading_attempts(app: Flask, template, attempts) -> None:
- """This should help developers understand what failed"""
- info = [f"Locating template {template!r}:"]
- total_found = 0
- blueprint = None
- if request_ctx and request_ctx.request.blueprint is not None:
- blueprint = request_ctx.request.blueprint
- for idx, (loader, srcobj, triple) in enumerate(attempts):
- if isinstance(srcobj, Flask):
- src_info = f"application {srcobj.import_name!r}"
- elif isinstance(srcobj, Blueprint):
- src_info = f"blueprint {srcobj.name!r} ({srcobj.import_name})"
- else:
- src_info = repr(srcobj)
- info.append(f"{idx + 1:5}: trying loader of {src_info}")
- for line in _dump_loader_info(loader):
- info.append(f" {line}")
- if triple is None:
- detail = "no match"
- else:
- detail = f"found ({triple[1] or '<string>'!r})"
- total_found += 1
- info.append(f" -> {detail}")
- seems_fishy = False
- if total_found == 0:
- info.append("Error: the template could not be found.")
- seems_fishy = True
- elif total_found > 1:
- info.append("Warning: multiple loaders returned a match for the template.")
- seems_fishy = True
- if blueprint is not None and seems_fishy:
- info.append(
- " The template was looked up from an endpoint that belongs"
- f" to the blueprint {blueprint!r}."
- )
- info.append(" Maybe you did not place a template in the right folder?")
- info.append(" See https://flask.palletsprojects.com/blueprints/#templates")
- app.logger.info("\n".join(info))
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