feat: increment version to 0.0.16; enhance GROUP BY handling in SQL to MongoDB conversion to support aliases and complex expressions

Author: theboringhumane

internal/converter/converter_test.go

@@ -292,6 +292,39 @@ func TestConverter_ConvertSQLToMongo(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "SELECT with CAST and GROUP BY aliases",
+			sql:  "SELECT CAST(strftime(created_at, '%Y') AS INTEGER) as year, COUNT(*) as count FROM orders GROUP BY year",
+			expected: []map[string]interface{}{
+				{
+					"$group": map[string]interface{}{
+						"_id": map[string]interface{}{
+							"group_0": map[string]interface{}{
+								"$dateToString": map[string]interface{}{
+									"date":   "$created_at",
+									"format": "%Y",
+								},
+							},
+						},
+						"count": map[string]interface{}{
+							"$sum": 1,
+						},
+					},
+				},
+				{
+					"$project": map[string]interface{}{
+						"_id":   0,
+						"count": "$count",
+						"year": map[string]interface{}{
+							"$dateToString": map[string]interface{}{
+								"date":   "$created_at",
+								"format": "%Y",
+							},
+						},
+					},
+				},
+			},
+		},
 		{
 			name:    "Invalid SQL",
 			sql:     "INVALID SQL QUERY",

internal/converter/parser.go

@@ -1226,6 +1226,14 @@ func (c *Converter) BuildGroupStage(groupBy sqlparser.GroupBy, selectExprs sqlpa
 		"_id": make(map[string]interface{}),
 	}
 
+	// Build a map of aliases to their expressions from SELECT clause
+	aliasMap := make(map[string]sqlparser.Expr)
+	for _, selExpr := range selectExprs {
+		if aliasedExpr, ok := selExpr.(*sqlparser.AliasedExpr); ok && !aliasedExpr.As.IsEmpty() {
+			aliasMap[aliasedExpr.As.String()] = aliasedExpr.Expr
+		}
+	}
+
 	// Handle GROUP BY columns
 	idGroup := group["_id"].(map[string]interface{})
 	for i, expr := range groupBy {
@@ -1234,7 +1242,20 @@ func (c *Converter) BuildGroupStage(groupBy sqlparser.GroupBy, selectExprs sqlpa
 		case *sqlparser.ColName:
 			colName := c.getFullColumnName(groupExpr)
 			fieldName := groupExpr.Name.String()
-			idGroup[fieldName] = "$" + colName
+
+			// Check if this is an alias from the SELECT clause
+			if aliasedExpr, isAlias := aliasMap[fieldName]; isAlias {
+				// Use the original expression instead of the alias
+				fieldName = fmt.Sprintf("group_%d", i)
+				aliasExpr, err := c.buildFunctionExpression(aliasedExpr.(*sqlparser.FuncExpr))
+				if err != nil {
+					return nil, fmt.Errorf("failed to build GROUP BY alias expression: %w", err)
+				}
+				idGroup[fieldName] = aliasExpr
+			} else {
+				// Regular column reference
+				idGroup[fieldName] = "$" + colName
+			}
 		case *sqlparser.FuncExpr:
 			// Handle function expressions in GROUP BY (like CAST(strftime(...)))
 			// Use generic field name for complex expressions

version.go

@@ -1,3 +1,3 @@
 package main
 
-var Version = "0.0.15"
+var Version = "0.0.16"