fix: treat a .pyiceberg.yaml without a mapping as no config - #3915
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`_load_yaml` passed `strictyaml.load(...).data` straight to `_lowercase_dictionary_keys`. For an empty or comment-only document that value is a `str`, not a mapping, so the call raised `AttributeError: 'str' object has no attribute 'items'`. `Config()` runs at import time, so commenting out the file made `import pyiceberg.catalog` fail with an error naming neither YAML nor the file. Return `None` instead, which the annotated return type already allows and which the caller already handles as "keep looking". Co-Authored-By: Claude Code <noreply@anthropic.com>
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🟢 Approval recommended
The change is narrowly scoped, matches the stated rationale, and is covered by a focused regression test for the previously failing cases.
Pull request overview
This PR fixes a failure mode in pyiceberg.utils.config.Config where an empty or comment-only .pyiceberg.yaml could cause an AttributeError during import-time configuration loading. It does this by treating configuration files that don’t parse to a mapping as “no config” and continuing the normal lookup behavior.
Changes:
- Guard
_load_yamlso non-mapping YAML documents returnNoneinstead of being passed into_lowercase_dictionary_keys. - Add a parametrized regression test covering empty, newline-only, and comment-only
.pyiceberg.yamlcontents.
File summaries
| File | Description |
|---|---|
pyiceberg/utils/config.py |
Adds a type guard to skip non-mapping YAML documents during config file loading. |
tests/utils/test_config.py |
Adds a regression test ensuring non-mapping config files are treated as absent. |
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- Review effort level: Lite
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Fokko
approved these changes
Sep 7, 2026
Fokko
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Sounds like a very reasonable change, thanks @jackylee-ch for fixing this 👍
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Thanks. @Fokko |
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Rationale for this change
_load_yamlpassesstrictyaml.load(...).datastraight to_lowercase_dictionary_keys. For an empty or comment-only document that value is astr, not a mapping, so the call raisesAttributeError: 'str' object has no attribute 'items'.Config()runs at import time, so commenting out~/.pyiceberg.yamlmakes the import fail with an error that names neither YAML nor the file:Return
Noneinstead. The annotated return type is alreadyRecursiveDict | None, and the caller already treatsNoneas "keep looking in the next directory".Are these changes tested?
Yes,
test_from_configuration_files_without_a_mappingintests/utils/test_config.py, parametrized over an empty file, a newline, and a comment-only file. All three fail with theAttributeErrorwithout the change.Are there any user-facing changes?
A
.pyiceberg.yamlthat holds no mapping is skipped instead of raising.