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import os
import typing as t
from warnings import warn
from .app import Flask
from .blueprints import Blueprint
from .globals import _request_ctx_stack
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 by Flask in debug mode if it detects a
redirect caused by the routing system when the request method is not
GET, HEAD or OPTIONS. Reasoning: form data will be dropped.
"""
def __init__(self, request):
exc = request.routing_exception
buf = [
f"A request was sent to this URL ({request.url}) but a"
" redirect was issued automatically by the routing system"
f" to {exc.new_url!r}."
]
# In case just a slash was appended we can be extra helpful
if f"{request.base_url}/" == exc.new_url.split("?")[0]:
buf.append(
" The URL was defined with a trailing slash so Flask"
" will automatically redirect to the URL with the"
" trailing slash if it was accessed without one."
)
buf.append(
" Make sure to directly send your"
f" {request.method}-request to this URL since we can't make"
" browsers or HTTP clients redirect with form data reliably"
" or without user interaction."
)
buf.append("\n\nNote: this exception is only raised in debug mode")
AssertionError.__init__(self, "".join(buf).encode("utf-8"))
def attach_enctype_error_multidict(request):
"""Since Flask 0.8 we're monkeypatching the files object in case a
request is detected that does not use multipart form data but the files
object is accessed.
"""
oldcls = request.files.__class__
class newcls(oldcls):
def __getitem__(self, key):
try:
return oldcls.__getitem__(self, key)
except KeyError as e:
if key not in request.form:
raise
raise DebugFilesKeyError(request, key) from e
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
reqctx = _request_ctx_stack.top
if reqctx is not None and reqctx.request.blueprint is not None:
blueprint = reqctx.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))
def explain_ignored_app_run() -> None:
if os.environ.get("WERKZEUG_RUN_MAIN") != "true":
warn(
Warning(
"Silently ignoring app.run() because the application is"
" run from the flask command line executable. Consider"
' putting app.run() behind an if __name__ == "__main__"'
" guard to silence this warning."
),
stacklevel=3,
)
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