#35177: Admin.display decorator functions do not output correct-format for
'modern'
Python string-formatting
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
stephenskett |
Type: Bug | Status: new
Component: | Version: 4.2
contrib.admin | Keywords: admin, display,
Severity: Normal | string, format,
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I am trying to write an admin display function (using the
[https://github.com/django/django/blob/main/django/contrib/admin/decorators.py
admin.display decorator]) to output the values of a float-field to 3
decimal places.
Seemed like this should be pretty simple, and indeed it is, **IF** you use
'old-style' Python format-strings, e.g.
{{{
class ModelFoo_Admin(admin.ModelAdmin):
@admin.display
def get_value_to_3dp(self, obj):
return "%.3f" % obj.bar
}}}
However, if you use either of the more 'modern'-style Python string-
formatting methods (i.e.
[https://docs.python.org/3/tutorial/inputoutput.html#the-string-format-
method str.format] or [https://docs.python.org/3/tutorial/inputoutput.html
#formatted-string-literals formatted string-literals]), the specified
string is not displayed using the specified formatting, i.e. this:
{{{
class ModelFoo_Admin(admin.ModelAdmin):
@admin.display
def get_value_to_3dp(self, obj):
return "{0:3f}".format(obj.bar)
}}}
or this:
{{{
class ModelFoo_Admin(admin.ModelAdmin):
@admin.display
def get_value_to_3dp(self, obj):
return f'{obj.bar:3f}'
}}}
display the output string to the default number of decimal-places (in my
case, 6), with trailing zeroes, rather than to 3 decimal places as
expected.
I don't understand why there would be any difference between these
approaches, so I am assuming this is a bug rather than the intended
behaviour.
--
Ticket URL: <https://code.djangoproject.com/ticket/35177>
Django <https://code.djangoproject.com/>
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