fix(mysql): render TINYINT(1) columns as boolean in SQL Lab and charts #35297
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Fixes MySQL TINYINT(1)/BOOLEAN columns displaying as numeric icons with 0/1 values instead of boolean representation with True/False in SQL Lab and Explore views. ## Changes ### Schema Mapping (mysql.py) - Add precise column_type_mappings for TINYINT(1), BOOLEAN, and BOOL patterns - Map to GenericDataType.BOOLEAN for proper metadata inspection - Ensures dataset schemas show boolean icons for actual boolean types only ### Runtime Conversion (mysql.py) - Implement fetch_data override with ultra-precise boolean detection - Convert 0/1 integers to True/False for TINYINT(1) columns - Use multiple reliable markers: FIELD_TYPE.TINY + display_size=1 OR SQLAlchemy type string - Extract _is_boolean_column helper method for clean detection logic - Enables pandas boolean dtype inference via extract_dataframe_dtypes ### Testing (test_mysql.py) - Add boolean type test cases to existing parametrized tests - Test TINYINT(1), BOOLEAN, BOOL → boolean mapping - Test TINYINT, TINYINT(2+) → numeric mapping (preserved behavior) ## Technical Details MySQL stores BOOLEAN as TINYINT(1) but returns 0/1 integers instead of Python booleans. This two-layer solution: 1. Maps TINYINT(1) metadata to GenericDataType.BOOLEAN for schema inspection 2. Converts query result values 0/1 → True/False for proper pandas inference The detection uses explicit width 1 or positive SQLAlchemy type string markers to avoid mis-converting broader TINYINT columns. Fixes: #35166 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <[email protected]>
…ersion
- Fix critical bug where bool('0') and bool(b'0') returned True instead of False
- Add proper type normalization for strings, bytes, and Decimal values
- Convert string/bytes/Decimal to int before applying bool() for accurate MySQL boolean conversion
- Maintains existing behavior for integer values while fixing edge cases
- Addresses feedback on conversion logic in mysql.py:323-330
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <[email protected]>
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Review by Korbit AI
Korbit automatically attempts to detect when you fix issues in new commits.
| Category | Issue | Status |
|---|---|---|
 |
Unreliable boolean column detection across drivers ▹ view | 🧠 Not in standard |
Files scanned
| File Path | Reviewed |
|---|---|
| superset/db_engine_specs/mysql.py | ✅ |
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| # Check SQLAlchemy type string (some drivers provide it at index 4) | ||
| if len(col_desc) > 4 and isinstance(col_desc[4], str): | ||
| sqla_type_str = col_desc[4].lower() | ||
| return any(marker in sqla_type_str for marker in ["bool", "tinyint(1)"]) |
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sadpandajoe
changed the title
| value = int(value) | ||
| elif isinstance(value, Decimal): | ||
| value = int(value) | ||
| new_row[col_idx] = bool(value) |
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I think this is a perfect case for column_type_mutators, see https://github.com/apache/superset/blob/master/superset/db_engine_specs/base.py#L342-L344 and https://github.com/apache/superset/blob/master/superset/db_engine_specs/base.py#L993-L998
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Unless @betodealmeida can think of a better way
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SUMMARY
Root Cause
MySQL boolean fields were incorrectly displaying as numeric icons with raw 0/1 values instead of readable True/False text in SQL Lab and Explore views. The issue had two layers:
Solution
Two-layer fix targeting MySQL's TINYINT(1) boolean representation:
Changes
BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF
TESTING INSTRUCTIONS
ADDITIONAL INFORMATION