fix: prevent IndexError: pop from empty list in RQ backend
#183
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In the RQ backend, if the `_django_tasks_exceptions` metadata key is missing or
empty, but the job has failed in the past, the `Job.task_result` would throw
this exception:
```
IndexError: pop from empty list
File "rq/job.py", line 1507, in execute_failure_callback
self.failure_callback(self, self.connection, *exc_info)
File "django_tasks/backends/rq.py", line 154, in failed_callback
task_result = job.task_result
File "django/utils/functional.py", line 47, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "django_tasks/backends/rq.py", line 127, in task_result
exception_class_path=exception_classes.pop(),
```
Then, since `Job.task_result` is accessed in `Job.perform`, this exception would
prevent any further jobs from being queued. This commit handles the case of an
empty or missing _django_tasks_exceptions metadata key by substituting in
`builtins.Exception` for the missing exception class path.
| # Get the underlying RQ job | ||
| job = cast(RQBackend, default_task_backend)._get_job(result.id) | ||
| self.assertIsNotNone(job) | ||
| assert job is not None |
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Question: What's the reason for this assertion? Or is it just to make mypy happy?
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Yes, you got it—it's to make mypy happy.
RealOrangeOne
approved these changes
Jul 16, 2025
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In the RQ backend, if the
_django_tasks_exceptionsmetadata key is missing or empty, but the job has failed in the past, theJob.task_resultwould throw this exception:Then, since
Job.task_resultis accessed inJob.perform, this exception would prevent any further jobs from being queued. This commit handles the case of an empty or missing _django_tasks_exceptions metadata key by substituting inbuiltins.Exceptionfor the missing exception class path.