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Edit File: debughelpers.py
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))