Opened 13 years ago
Closed 11 years ago
#16134 closed Bug (fixed)
django.db.models.fields.Field instance can not be compared with None
| Reported by: | Owned by: | Christopher Adams | |
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| Component: | Database layer (models, ORM) | Version: | 1.3 |
| Severity: | Normal | Keywords: | |
| Cc: | hongshuning@…, stefano.borgia@… | Triage Stage: | Accepted |
| Has patch: | yes | Needs documentation: | no |
| Needs tests: | no | Patch needs improvement: | yes |
| Easy pickings: | yes | UI/UX: | no |
Description
Instances of django.db.models.fields.Field can not be compared with None. Eg: field == None
Repro: Compare a field instance with None. This fails since cmp assumes the other operand is a field instance and eq and ne are not defined.
Attachments (2)
Change History (14)
comment:1 by , 13 years ago
| Triage Stage: | Unreviewed → Accepted |
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comment:2 by , 13 years ago
| Has patch: | set |
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comment:4 by , 13 years ago
| Triage Stage: | Ready for checkin → Accepted |
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| UI/UX: | unset |
Hmm... I'm a little unclear on the use-case for this. Instantiating fields is internal to Django -- normal models expose Python attributes and the Field instances are hidden in the Meta class (which is opaque). Making this change "just because we can" isn't necessary. What's the normal code pattern that triggers a problem here?
comment:5 by , 13 years ago
| Patch needs improvement: | set |
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comment:6 by , 12 years ago
| Cc: | added |
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by , 12 years ago
| Attachment: | 16134_fix2.diff added |
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comment:7 by , 12 years ago
I modify the test case according to mtredinnick's propose based on dev branch. The test case succeed without modify any code.
comment:8 by , 11 years ago
| Cc: | added |
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| Owner: | changed from to |
| Status: | new → assigned |
comment:9 by , 11 years ago
| Owner: | removed |
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| Status: | assigned → new |
comment:10 by , 11 years ago
| Owner: | set to |
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| Status: | new → assigned |
comment:11 by , 11 years ago
Simon Charette's commit at 5cbfb48b (intended to fix #17851) actually resolves this issue also. This commit made its way into stable/1.5.x but is not yet in stable/1.4.x. As this is not a security issue, both Russell Keith-Magee and Andrew Godwin tell me not to bother with a pull request.
comment:12 by , 11 years ago
| Resolution: | → fixed |
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| Status: | assigned → closed |
Accepted. (BTW, the standard Python idiom for comparing against None is '
x is None' or 'x is not None', rather than==or!=, because it is more efficient and unambiguous. But the ticket is valid nonetheless).