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Diffstat (limited to 'python/flask/debughelpers.py')
| -rw-r--r-- | python/flask/debughelpers.py | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/python/flask/debughelpers.py b/python/flask/debughelpers.py new file mode 100644 index 0000000..e9765f2 --- /dev/null +++ b/python/flask/debughelpers.py @@ -0,0 +1,168 @@ +# -*- coding: utf-8 -*- +""" + flask.debughelpers + ~~~~~~~~~~~~~~~~~~ + + Various helpers to make the development experience better. + + :copyright: © 2010 by the Pallets team. + :license: BSD, see LICENSE for more details. +""" + +import os +from warnings import warn + +from ._compat import implements_to_string, 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) |