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