FIX: exception pickle/unpickle round-trip#616
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Add __reduce__ to the base Exception class and ConnectionStringParseError so that pickle.loads(pickle.dumps(exc)) reconstructs the exception with the correct constructor arguments. Previously, super().__init__(self.message) stored only one combined string in self.args, but __init__ requires two positional arguments (driver_error, ddbc_error). This caused TypeError on unpickle, breaking multiprocessing, concurrent.futures, celery, and copy.deepcopy. Fixes #587
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Pull request overview
Improves exception serialization in mssql_python so driver-defined DB-API exceptions (and ConnectionStringParseError) can be pickled/unpickled reliably—important for multiprocessing and cross-process error propagation.
Changes:
- Added
__reduce__implementations forConnectionStringParseErrorand the DB-API exception base class to support pickle/unpickle round-trips. - Added tests verifying pickle round-trip behavior (and
copy.deepcopy) for DB-API exception subclasses andConnectionStringParseError.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
mssql_python/exceptions.py |
Adds __reduce__ hooks to make custom exceptions pickle/unpickle friendly. |
tests/test_006_exceptions.py |
Adds coverage ensuring exceptions survive pickle/unpickle and deepcopy round-trips. |
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📊 Code Coverage Report
Diff CoverageDiff: main...HEAD, staged and unstaged changes
Summary
📋 Files Needing Attention📉 Files with overall lowest coverage (click to expand)mssql_python.pybind.logger_bridge.cpp: 59.2%
mssql_python.pybind.ddbc_bindings.h: 59.7%
mssql_python.pybind.logger_bridge.hpp: 70.8%
mssql_python.pybind.ddbc_bindings.cpp: 76.1%
mssql_python.row.py: 76.9%
mssql_python.__init__.py: 77.3%
mssql_python.pybind.connection.connection.cpp: 77.3%
mssql_python.ddbc_bindings.py: 79.6%
mssql_python.logging.py: 85.5%
mssql_python.connection.py: 85.6%🔗 Quick Links
|
… jahnvi/fix-exception-pickle-587
sumitmsft
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Jun 4, 2026
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gargsaumya
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Jun 12, 2026
[AB#45750](https://sqlclientdrivers.visualstudio.com/c6d89619-62de-46a0-8b46-70b92a84d85e/_workitems/edit/45750) Release mssql-python v1.9.0. Bumps `__version__`, `setup.py` version, and updates `PyPI_Description.md` with this release's customer-facing changes. ### Summary #### Enhancements - **Row Objects in Bulk Copy** - `bulkcopy` now accepts `Row` objects (and lists) directly, converting each row to a tuple automatically (#615). - **Cached Parameter Type Resolution for NULLs** - `SQLDescribeParam` results are cached per statement when binding `NULL` parameters, removing redundant server round-trips and fixing incorrect type fallbacks for all-NULL columns and VARBINARY types (#614). #### Bug Fixes - **macOS / Linux Import Failure** - simdutf is now always statically linked via FetchContent, fixing import/symbol failures on machines without simdutf at the CI build path (#608). Resolves #607, #628. - **executemany Large Decimal Handling** - Fixed a `SQL_C_NUMERIC` type mismatch when inserting `Decimal` values outside the SQL Server `MONEY` range via `executemany` (#611). Resolves #609. - **Exception Pickling** - DB-API exception subclasses and `ConnectionStringParseError` now implement `__reduce__` for correct pickle/unpickle round-trips (#616). Resolves #587. - **PRINT Messages in nextset()** - Diagnostic messages from subsequent result sets are captured on `SQL_SUCCESS_WITH_INFO` during `nextset()` (#618). Resolves #612. - **Row Objects in executemany DAE Path** - `executemany` converts `Row` objects to tuples in the DAE fallback path, fixing `varchar(max)` writes (#630). Resolves #629. - **Static Type-Checking of Fetch Methods** - `fetchone`/`fetchmany`/`fetchall` are no longer reassigned as instance attributes, fixing type-checking under `ty` (#631). Resolves #620. #### Version bump - `mssql_python/__init__.py`: `__version__` 1.8.0 → 1.9.0 - `setup.py`: version 1.8.0 → 1.9.0 - `PyPI_Description.md`: updated "What's new" section to v1.9.0 Bundled `mssql_py_core` version unchanged (0.1.4).
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Work Item / Issue Reference
Summary
This pull request improves the serialization support for custom exception classes in the codebase, specifically ensuring that all DB-API exception subclasses can be pickled and unpickled (serialized and deserialized) correctly. It does so by implementing the
__reduce__method for relevant exception classes and by adding comprehensive tests to verify this behavior.Serialization support for exceptions:
__reduce__method toConnectionStringParseErrorand all DB-API exception subclasses to enable correct pickling and unpickling, preserving all relevant attributesTesting improvements:
tests/test_006_exceptions.pyto verify that all DB-API exception subclasses andConnectionStringParseErrorsurvive a pickle/unpickle round-trip, including cases with empty attributes and deep copies.