fix: error when registering TaskResultAdmin on proxy model

[ClanEver]

Closes #394

I have tested using field.name for field in self.model._meta.fields on both the original model and the proxy model, and it works as expected.

[auvipy]

thanks for handling it. is there any way to verify the change? tests, screenshots etc?

[ClanEver]

I have added tests. The results before and after the modification are as follows:

Before the modification:

pytest t/unit/test_admin.py
============================= test session starts ==============================
platform linux -- Python 3.13.2, pytest-7.4.4, pluggy-1.6.0
django: version: 5.2.5, settings: t.proj.settings (from ini)
benchmark: 5.0.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
rootdir: /home/clanever/dev/python/django-celery-results
configfile: setup.cfg
plugins: django-4.11.1, benchmark-5.0.1
collected 4 items

t/unit/test_admin.py ..FF                                                [100%]

# Omitting lengthy FAILURES here

=========================== short test summary info ============================
FAILED t/unit/test_admin.py::TaskResultProxyAdminTests::test_add_view - django.core.exceptions.FieldError: 'result' cannot be specified for TaskResultProxy model form as it ...
FAILED t/unit/test_admin.py::TaskResultProxyAdminTests::test_change_view - django.core.exceptions.FieldError: 'result' cannot be specified for TaskResultProxy model form as it ...
========================= 2 failed, 2 passed in 2.51s ==========================

After the modification:

pytest t/unit/test_admin.py
========================================== test session starts ===========================================
platform linux -- Python 3.13.2, pytest-7.4.4, pluggy-1.6.0
django: version: 5.2.5, settings: t.proj.settings (from ini)
benchmark: 5.0.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
rootdir: /home/clanever/dev/python/django-celery-results
configfile: setup.cfg
plugins: django-4.11.1, benchmark-5.0.1
collected 4 items                                                                                        

t/unit/test_admin.py ....                                                                          [100%]

=========================================== 4 passed in 2.65s ============================================

tox has also passed.

[auvipy]

please check the failing test

[ClanEver]

I've tried to fix it. Please let me know if any improvements are needed.

[Copilot]

Pull Request Overview

This PR fixes an error that occurs when registering TaskResultAdmin on a Django proxy model by changing the field reference from self.opts.local_fields to self.model._meta.fields.

• Updates the get_readonly_fields method in TaskResultAdmin to use the correct field reference for proxy models
• Adds comprehensive test coverage for both regular and proxy model scenarios

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
django_celery_results/admin.py	Fixed field reference in get_readonly_fields method to work with proxy models
t/unit/test_admin.py	Added test cases for TaskResultAdmin functionality with both regular and proxy models

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