#10834 closed (fixed)
BaseHandler does not handle resolver returning None
Reported by: | xerolas | Owned by: | ccahoon |
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Component: | HTTP handling | Version: | dev |
Severity: | Keywords: | ||
Cc: | chris.cahoon@… | Triage Stage: | Accepted |
Has patch: | yes | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
django.core.handler.base.BaseHandler has the following call to the resolver:
callback, callback_args, callback_kwargs = resolver.resolve( request.path_info)
However resolve() can return None (this happens to me when I get bogus HTTP requests from bots) and TypeError is not explicitly caught (for trying to unpack None).
The result is that 500 is returned instead of 404 and an email to the admins is sent (by default).
Attachments (2)
Change History (21)
comment:1 by , 16 years ago
Triage Stage: | Unreviewed → Accepted |
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comment:2 by , 16 years ago
Owner: | changed from | to
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comment:3 by , 16 years ago
Has patch: | set |
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I raise a Resolver404 if self.regex.search(path) returns None. This happens if path is not a regular expression. The unit test gives some examples of test cases that caused resolver to return None before the patch.
by , 16 years ago
Attachment: | ticket10834.diff added |
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regression text and fix, updated to exclude the else statement
comment:4 by , 15 years ago
Cc: | added |
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milestone: | → 1.1 |
comment:5 by , 15 years ago
Cc: | added |
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comment:6 by , 15 years ago
Resolution: | → fixed |
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Status: | new → closed |
follow-up: 9 comment:7 by , 15 years ago
This fixed breaks the debug screen. When setting up a new app and setting entries in the urls.py file, you will still get the default blue 'Welcome to django' screen instead of the 404 debug screen.
comment:8 by , 15 years ago
Resolution: | fixed |
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Status: | closed → reopened |
comment:9 by , 15 years ago
Replying to mwelch:
This fixed breaks the debug screen. When setting up a new app and setting entries in the urls.py file, you will still get the default blue 'Welcome to django' screen instead of the 404 debug screen.
Please provide more information. Using r11126 I cannot recreate any problem getting the 404 debug screen to show up when I have DEBUG set to True and attempt to access a URL that has no mapping in my urlpatterns.
comment:10 by , 15 years ago
Sorry, anonymous at 7:01:33 was me. (Normally the spam blocker lets me know when my login has expired but not this time.)
comment:11 by , 15 years ago
That's very interesting. I was able to recreate showing the Welcome to Django screen if the following urlpattern is not covered:
r'^$'
However, the other urls still functioned properly. I looked around and it looks like it is because of this code in django/views/debug.py (this is on trunk r11126):
244 def technical_404_response(request, exception): 245 "Create a technical 404 error response. The exception should be the Http404." 246 try: 247 tried = exception.args[0]['tried'] 248 except (IndexError, TypeError): 249 tried = [] 250 else: 251 if not tried: 252 # tried exists but is an empty list. The URLconf must've been empty. 253 return empty_urlconf(request)
The content of the changeset (which was different from my patch) creates an empty "tried" list in the dictionary returned in the Resolver404 exception. Thus, debug thinks there is nothing in the urlconf. Attaching a patch.
I am pretty sure I ran into this issue when creating the fix -- only by not even having "tried" in the dictionary does the 404 behave properly. Now I am not sure if this is correct overall behavior, but for a patch this small, it seemed appropriate to just leave it out.
comment:12 by , 15 years ago
@ccahoon: There must be something else going on here, because removing tried
from the dictionary causes mass test failures in the test_client and test_client_regress unit tests. Your analysis regarding why tried
should be omitted looks sound, though - we'll have to dig deeper to find the cause of the failures in the test_client tests.
comment:13 by , 15 years ago
@russellm: I've had very recent experience with test_client_regress expecting behavior that is consistent with Django but not necessarily correct. I will take a look and see what is going on later tonight.
comment:14 by , 15 years ago
Cc: | removed |
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That patch passes the test_client_regress tests and seems to behave properly in real use. The machine I made the change on can't handle running the full test suite at the moment, so I do not know about other regression tests.
comment:15 by , 15 years ago
The patch above passes the regression test suite. @russellm, what do you think of the solution?
comment:16 by , 15 years ago
@ccahoon - Not thrilled. The format of the error message with the provided patch is completely misleading. I suspect the patch will need to be more than a single line change - looking at the code, there may be a need to tweak the 404 template to differentiate between the error case described here, and the "new project, no URL's" message.
comment:17 by , 15 years ago
Resolution: | → fixed |
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Status: | reopened → closed |
This is probably addressing the wrong end of the issue. As things stand, there is a problem. But it isn't that we aren't handling None. It's that we are seeing None in the first place.
We should be raising an exception (either
Http404
orResolver404
might be appropriate). It's an exceptional condition and should enter the normal code paths for handling non-existent URLs, not require special handling in the non-exceptional path.