#35766: Choice iterator breaks when using slices
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Reporter: David | Type: Uncategorized
Status: new | Component: Uncategorized
Version: 5.0 | Severity: Normal
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Currently the choice-iterator classes introduced in
https://code.djangoproject.com/ticket/24561 are designed to work with
index-based access.
{{{#!python
class MyModel(models.Model):
field = models.IntegerField(choices=lambda: range(10))
the_field = MyModel._meta.get_field("field")
the_field.choices[2]
#> 3
}}}
Since choices has been out for long time accepting there are libraries in
which the `field.choices` attribute was used as it it was a tuple/list,
which can be accessed also with slicing syntax (see [https://github.com
/sphinx-doc/sphinxcontrib-
django/blob/e9d43085ffc9b921fd7d880ff38d4e1d24d8d791/sphinxcontrib_django/docstrings/attributes.py#L123-L127
sphinxcontrib-django ]), this now raises an error:
{{{#!python
the_field.choices[:2]
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
Cell In[13], line 1
----> 1 the_field.choices[:2]
File /opt/venv/lib/python3.10/site-packages/django/utils/choices.py:24, in
BaseChoiceIterator.__getitem__(self, index)
23 def __getitem__(self, index):
---> 24 if index < 0:
25 # Suboptimally consume whole iterator to handle negative
index.
26 return list(self)[index]
27 try:
}}}
The
[https://docs.python.org/3.10/reference/datamodel.html?highlight=slicing#object.__getitem__
__getitem__] states that the management of key type should be handled in
the implementation.
It should be choosen if slices are going to be supported or if only
integers are going to be supported by this class.
--
Ticket URL: <https://code.djangoproject.com/ticket/35766>
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