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# -*- coding: utf-8 -*-
"""
flask.debughelpers
~~~~~~~~~~~~~~~~~~
Various helpers to make the development experience better.
:copyright: 2010 Pallets
:license: BSD-3-Clause
"""
import os
from warnings import warn
from ._compat import implements_to_string
from ._compat import text_type
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.
"""
@implements_to_string
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 = [
'You tried to access the file "%s" in the request.files '
"dictionary but it does not exist. The mimetype for the request "
'is "%s" 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.'
% (key, request.mimetype)
]
if form_matches:
buf.append(
"\n\nThe browser instead transmitted some file names. "
"This was submitted: %s" % ", ".join('"%s"' % x for x in form_matches)
)
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 = [
"A request was sent to this URL (%s) but a redirect was "
'issued automatically by the routing system to "%s".'
% (request.url, exc.new_url)
]
# In case just a slash was appended we can be extra helpful
if 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 %s-request to this URL "
"since we can't make browsers or HTTP clients redirect "
"with form data reliably or without user interaction." % request.method
)
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:
if key not in request.form:
raise
raise DebugFilesKeyError(request, key)
newcls.__name__ = oldcls.__name__
newcls.__module__ = oldcls.__module__
request.files.__class__ = newcls
def _dump_loader_info(loader):
yield "class: %s.%s" % (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, text_type)) for x in value):
continue
yield "%s:" % key
for item in value:
yield " - %s" % item
continue
elif not isinstance(value, (str, text_type, int, float, bool)):
continue
yield "%s: %r" % (key, value)
def explain_template_loading_attempts(app, template, attempts):
"""This should help developers understand what failed"""
info = ['Locating template "%s":' % template]
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 = 'application "%s"' % srcobj.import_name
elif isinstance(srcobj, Blueprint):
src_info = 'blueprint "%s" (%s)' % (srcobj.name, srcobj.import_name)
else:
src_info = repr(srcobj)
info.append("% 5d: trying loader of %s" % (idx + 1, src_info))
for line in _dump_loader_info(loader):
info.append(" %s" % line)
if triple is None:
detail = "no match"
else:
detail = "found (%r)" % (triple[1] or "<string>")
total_found += 1
info.append(" -> %s" % 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 to the blueprint "%s".' % blueprint
)
info.append(" Maybe you did not place a template in the right folder?")
info.append(" See http://flask.pocoo.org/docs/blueprints/#templates")
app.logger.info("\n".join(info))
def explain_ignored_app_run():
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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