FIX: Setinputsizes() SQL_DECIMAL crash

[jahnvi480]

Work Item / Issue Reference

AB#53990

GitHub Issue: #503

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Summary

This pull request improves the handling of Python Decimal values when binding to SQL DECIMAL and NUMERIC types, especially when using setinputsizes and executemany. It fixes a runtime error by ensuring Decimal objects are converted to strings for proper binding, and adds comprehensive tests to verify this behavior.

Decimal binding and conversion improvements:

• Changed the mapping for SQL DECIMAL and NUMERIC types to use SQL_C_CHAR instead of SQL_C_NUMERIC in _get_c_type_for_sql_type, enabling string-based binding for decimals.
• Updated parameter handling in _create_parameter_types_list and executemany to convert Python Decimal objects to strings when binding to SQL DECIMAL or NUMERIC columns.

Testing enhancements:

• Added new tests in test_004_cursor.py to verify that setinputsizes with SQL_DECIMAL and SQL_NUMERIC accepts Python Decimal values, works with both executemany and execute, and correctly handles NULL values.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR fixes a crash when binding Python Decimal values to SQL DECIMAL/NUMERIC using setinputsizes() (notably with executemany) by switching to string-based binding and adding regression tests.

Changes:

• Map SQL DECIMAL/NUMERIC to SQL_C_CHAR for C-type binding and convert Python Decimal values to strings during parameter processing.
• Update executemany preprocessing to convert Decimal values when SQL type is DECIMAL/NUMERIC.
• Add new cursor tests covering setinputsizes() + SQL_DECIMAL/SQL_NUMERIC with executemany, execute, and NULL.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
mssql_python/cursor.py	Switches DECIMAL/NUMERIC binding to SQL_C_CHAR and adds Decimal-to-string conversions in parameter handling paths.
tests/test_004_cursor.py	Adds regression tests validating Decimal binding via setinputsizes() for execute/executemany and NULL handling.

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[github-actions]

📊 Code Coverage Report

🔥 Diff Coverage 77%

🎯 Overall Coverage 79%

📈 Total Lines Covered: 6663 out of 8408 📁 Project: mssql-python

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Diff Coverage

Diff: main...HEAD, staged and unstaged changes

• mssql_python/cursor.py (77.8%): Missing lines 2327-2328

Summary

• Total: 9 lines
• Missing: 2 lines
• Coverage: 77%

mssql_python/cursor.py

Lines 2323-2332

  2323                         processed_row[i] = format(val, "f")
  2324                     else:
  2325                         try:
  2326                             processed_row[i] = format(decimal.Decimal(str(val)), "f")
! 2327                         except Exception as e:  # pylint: disable=broad-exception-caught
! 2328                             raise ValueError(
  2329                                 f"Failed to convert parameter at row {row}, column {i} to Decimal: {e}"
  2330                             ) from e
  2331             processed_parameters.append(processed_row)

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📋 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: 67.8%
mssql_python.row.py: 70.5%
mssql_python.pybind.logger_bridge.hpp: 70.8%
mssql_python.pybind.ddbc_bindings.cpp: 74.5%
mssql_python.pybind.connection.connection.cpp: 75.3%
mssql_python.__init__.py: 77.3%
mssql_python.ddbc_bindings.py: 79.6%
mssql_python.pybind.connection.connection_pool.cpp: 79.6%
mssql_python.connection.py: 85.2%

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