Implementation Plan for JavaScript Property Access in SQL

• Analyze current test341.js structure and requirements
• Understand parser grammar for Expressions and Columns
• Build project and run tests to verify baseline
• Fix test 4 expected result (should be 1, not [6, 6, 7])
• Implement property access detection in compileSelect1 (src/424select.js)
• Add property access code generation for Column patterns
• Implement property access in Column.toJS (src/50expression.js)
• Test implementation with test 4 (SET with property access)
• Test implementation with test 5 (SELECT COLUMN with property access)
• Enable tests by removing .skip
• Run full test suite to verify no regressions (2086 tests passing)
• Code review and final validation
• Add test for table.column.length syntax

Implementation Summary

Successfully implemented JavaScript property access using dot notation in SQL queries. The implementation enables seamless JavaScript integration by allowing developers to access object properties directly within SQL statements.

Features Implemented ✅

1. String Literal Property Access:"hello".length → 5
2. SET Variable with Property:SET @a = "who".length →@A = 3
3. Column Property Access:SELECT COLUMN name.length FROM persons → [6, 6, 7]
4. Table.Column.Property Access:SELECT COLUMN persons.name.length FROM persons → [6, 6, 7]
5. WHERE Clause Property Access:WHERE name.length > 6 → Works correctly
6. Arrow Operator Compatibility:name->length → Still works as before
7. Traditional Syntax:table.column → Unchanged behavior

Changes Made

1. Property Access Detection (src/424select.js):

   • Added logic incompileSelect1 to detect when a Column'stableid is actually a column name (not a table)
   • Checksquery.defcols to determine if we're dealing with property access pattern (e.g.,name.length)
   • Generates appropriate JavaScript code for property access:((p['table']['column'] || {})['property'])

2. Column.toJS Enhancement (src/50expression.js):

   • Added property access detection inColumn.toJS method
   • Whentableid exists in defcols, treats it as property access pattern
   • Falls back to normal table.column behavior for traditional syntax

3. Test Fixes (test/test341.js):

   • Enabled test 4: "JavaScript way" for SET with property access
   • Fixed test 4 assertion (was expecting [6,6,7], now correctly expects 1 with@A=3)
   • Enabled test 5: "JavaScript way" for SELECT COLUMN with property access
   • Added test 6: "JavaScript way with table.column.length" for three-level dot notation
   • All tests now pass successfully

Test Results

• Total Tests: 2086 passing, 367 pending
• New Tests Enabled: 3 (from test341.js - tests 4, 5, and 6)
• Regressions: 0
• Test Coverage: All use cases verified including three-level dot notation

Implementation Details

The solution detects when a Column reference patternA.B represents property access (column A, property B) rather than table.column access by checking ifA exists in thequery.defcols dictionary, which maps column names to their source tables. IfA is a column, we generate safe JavaScript code with null-checking:((p['table']['column'] || {})['property']). Otherwise, we use the traditional table.column interpretation.

The implementation also supports three-level dot notation liketable.column.property which works seamlessly with the existing logic.

Security Considerations

• Property access uses safe object navigation with|| {} fallback
• No arbitrary code execution introduced
• Limited to property access only (methods require-> operator)
• Maintains existing security boundaries

Status: ✅ Complete and ready for merge

// Test 4: JavaScript way (line 38)it.skip('4. JavaScript way',function(done){varres=alasql('SET @a = "who".length');assert.deepEqual(res,[6,6,7]);done();});// Test 5: JavaScript way (line 44)it.skip('5. JavaScript way',function(done){varres=alasql('SELECT COLUMN name.length FROM persons');assert.deepEqual(res,[6,6,7]);done();});

// Test 4: JavaScript wayit('4. JavaScript way',function(done){varres=alasql('SET @a = "who".length');// Should return the length of the string "who"assert.deepEqual(res,[3]);// Note: Expected result may need clarificationdone();});// Test 5: JavaScript wayit('5. JavaScript way',function(done){// Setup test dataalasql('CREATE TABLE persons (name STRING)');alasql('INSERT INTO persons VALUES ("Andrey"), ("Valery"), ("Michael")');varres=alasql('SELECT COLUMN name.length FROM persons');assert.deepEqual(res,[6,6,7]);// Lengths of the namesdone();});

• FixesJavaScript Property Access in SQL - Object Property Navigation #2357

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