Fix: Resolve TypeError in value_to_type on Python 3.13 (issue #1188) #1189
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tconley1428
reviewed
Oct 27, 2025
tconley1428
reviewed
Oct 27, 2025
tconley1428
approved these changes
Oct 30, 2025
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What was changed
This PR fixes a TypeError in temporalio/converter.py that occurs on Python 3.13.
The isinstance(key, key_type) check in the value_to_type function was modified to include a guard: not isinstance(key_type, type). This prevents the illegal isinstance() call from being used on typing generics like typing.Literal.
A new unit test is also added to reproduce this specific bug and verify the fix.
Why?
On Python 3.13+, isinstance() can no longer be used with subscripted generics (like typing.Literal), and doing so raises a TypeError. The value_to_type function was not handling this, causing data conversion to fail for dictionaries with Literal keys.
This fix short-circuits the logic to avoid the illegal call, allowing the function to fall through to the correct value_to_type call which already handles Literal types properly.
Checklist
Closes [Bug] converter.py: TypeError on Python 3.13 when using isinstance with typing.Literal #1188
How was this tested:
A new unit test was added (test_value_to_type_literal_key_bug) that specifically reproduces this bug. This test fails before the fix and passes with it. The full test suite was also run successfully via poe test.
Any docs updates needed?
No. This is a minor internal bug fix.