#21563: calling hasattr(model_instance, fieldname) raises DoesNotExist when
False
-------------------------------------+-------------------------------------
Reporter: monkut | Owner: nobody
Type: | Status: new
Cleanup/optimization | Version: 1.6
Component: Database layer | Resolution:
(models, ORM) | Triage Stage: Accepted
Severity: Normal | Needs documentation: 0
Keywords: | Patch needs improvement: 0
Has patch: 0 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Changes (by aaugustin):
* needs_better_patch: => 0
* component: Uncategorized => Database layer (models, ORM)
* needs_tests: => 0
* needs_docs: => 0
* type: Uncategorized => Cleanup/optimization
* stage: Unreviewed => Accepted
Comment:
This is a bit tricky.
[http://docs.python.org/3/library/functions.html#hasattr Python's
documentation for hasattr] notes that it's "implemented by calling
`getattr(object, name)` and seeing whether it raises an `AttributeError`
or not". However, when no related object exists, Django raises
`DoesNotExist`, not `AttributeError`.
Could we raise a `RelatedObjectDoesNotExist` exception inheriting both
from `DoesNotExist` (for backwards compatibility) and `AttributeError` (to
change the behavior according to your suggestion)?
I'm not entirely sure it's a good idea, but it's worth considering.
--
Ticket URL: <https://code.djangoproject.com/ticket/21563#comment:1>
Django <https://code.djangoproject.com/>
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