fix: allow "length" as a column name in result rows

packages/libsql-client-wasm/src/wasm.ts

@@ -395,8 +395,6 @@ function rowFromSql(
     intMode: IntMode,
 ): Row {
     const row = {};
-    // make sure that the "length" property is not enumerable
-    Object.defineProperty(row, "length", { value: sqlRow.length });
     for (let i = 0; i < sqlRow.length; ++i) {
         const value = valueFromSql(sqlRow[i], intMode);
         Object.defineProperty(row, i, { value });
@@ -411,6 +409,11 @@ function rowFromSql(
             });
         }
     }
+    // make sure that the "length" property is not enumerable, unless a column
+    // is named "length", in which case the column value takes precedence
+    if (!Object.hasOwn(row, "length")) {
+        Object.defineProperty(row, "length", { value: sqlRow.length });
+    }
     return row as Row;
 }
 

packages/libsql-client/src/__tests__/client.test.ts

@@ -197,6 +197,24 @@ describe("execute()", () => {
         }),
     );
 
+    test(
+        'column named "length"',
+        withClient(async (c) => {
+            const rs = await c.execute("SELECT 1 AS one, 'two' AS \"length\"");
+            expect(rs.columns).toStrictEqual(["one", "length"]);
+            expect(rs.rows.length).toStrictEqual(1);
+
+            const r = rs.rows[0];
+            expect(r[0]).toStrictEqual(1);
+            expect(r[1]).toStrictEqual("two");
+            expect(r["length"]).toStrictEqual("two");
+            expect(Object.entries(r)).toStrictEqual([
+                ["one", 1],
+                ["length", "two"],
+            ]);
+        }),
+    );
+
     test(
         "statement that produces error",
         withClient(async (c) => {
@@ -994,6 +1012,16 @@ describe("ResultSet.toJSON()", () => {
         }),
     );
 
+    test(
+        'column named "length"',
+        withClient(async (c) => {
+            const rs = await c.execute("SELECT 1 AS one, 'two' AS \"length\"");
+            const json = rs.toJSON();
+            expect(json["columns"]).toStrictEqual(["one", "length"]);
+            expect(json["rows"]).toStrictEqual([[1, "two"]]);
+        }),
+    );
+
     (hasHrana2 ? test : test.skip)(
         "row values",
         withClient(async (c) => {

packages/libsql-client/src/hrana.ts

@@ -2,6 +2,7 @@ import * as hrana from "@libsql/hrana-client";
 import type {
     InStatement,
     ResultSet,
+    Row,
     Transaction,
     TransactionMode,
     InArgs,
@@ -384,7 +385,15 @@ export function stmtToHrana(stmt: InStatement | [string, InArgs?]): hrana.Stmt {
 export function resultSetFromHrana(hranaRows: hrana.RowsResult): ResultSet {
     const columns = hranaRows.columnNames.map((c) => c ?? "");
     const columnTypes = hranaRows.columnDecltypes.map((c) => c ?? "");
-    const rows = hranaRows.rows;
+    let rows: Array<Row> = hranaRows.rows;
+    if (columns.includes("length")) {
+        // Rows produced by @libsql/hrana-client have a non-configurable
+        // "length" property which hides a column named "length", so the rows
+        // are rebuilt to make the column value take precedence.
+        rows = hranaRows.rows.map((hranaRow) =>
+            rowFromHrana(hranaRow, hranaRows.columnNames),
+        );
+    }
     const rowsAffected = hranaRows.affectedRowCount;
     const lastInsertRowid =
         hranaRows.lastInsertRowid !== undefined
@@ -399,6 +408,33 @@ export function resultSetFromHrana(hranaRows: hrana.RowsResult): ResultSet {
     );
 }
 
+function rowFromHrana(
+    hranaRow: hrana.Row,
+    colNames: Array<string | undefined>,
+): Row {
+    const row = {};
+    for (let i = 0; i < colNames.length; ++i) {
+        const value = hranaRow[i];
+        Object.defineProperty(row, i, { value });
+
+        const colName = colNames[i];
+        if (colName !== undefined && !Object.hasOwn(row, colName)) {
+            Object.defineProperty(row, colName, {
+                value,
+                enumerable: true,
+                configurable: true,
+                writable: true,
+            });
+        }
+    }
+    // make sure that the "length" property is not enumerable, unless a column
+    // is named "length", in which case the column value takes precedence
+    if (!Object.hasOwn(row, "length")) {
+        Object.defineProperty(row, "length", { value: colNames.length });
+    }
+    return row as Row;
+}
+
 export function mapHranaError(e: unknown): unknown {
     if (e instanceof hrana.ClientError) {
         const code = mapHranaErrorCode(e);

packages/libsql-client/src/sqlite3.ts

@@ -724,8 +724,6 @@ function rowFromSql(
     intMode: IntMode,
 ): Row {
     const row = {};
-    // make sure that the "length" property is not enumerable
-    Object.defineProperty(row, "length", { value: sqlRow.length });
     for (let i = 0; i < sqlRow.length; ++i) {
         const value = valueFromSql(sqlRow[i], intMode);
         Object.defineProperty(row, i, { value });
@@ -740,6 +738,11 @@ function rowFromSql(
             });
         }
     }
+    // make sure that the "length" property is not enumerable, unless a column
+    // is named "length", in which case the column value takes precedence
+    if (!Object.hasOwn(row, "length")) {
+        Object.defineProperty(row, "length", { value: sqlRow.length });
+    }
     return row as Row;
 }
 

packages/libsql-core/src/util.ts

@@ -50,7 +50,7 @@ export class ResultSetImpl implements ResultSet {
         return {
             columns: this.columns,
             columnTypes: this.columnTypes,
-            rows: this.rows.map(rowToJson),
+            rows: this.rows.map((row) => rowToJson(row, this.columns.length)),
             rowsAffected: this.rowsAffected,
             lastInsertRowid:
                 this.lastInsertRowid !== undefined
@@ -60,8 +60,14 @@ export class ResultSetImpl implements ResultSet {
     }
 }
 
-function rowToJson(row: Row): unknown {
-    return Array.prototype.map.call(row, valueToJson);
+function rowToJson(row: Row, columnCount: number): unknown {
+    // a column may be named "length", in which case `row.length` is the
+    // column value rather than the number of columns
+    const values: Array<unknown> = [];
+    for (let i = 0; i < columnCount; ++i) {
+        values.push(valueToJson(row[i]));
+    }
+    return values;
 }
 
 function valueToJson(value: Value): unknown {