fix(winston-transport): Add attribute serialization

packages/winston-transport/src/utils.ts

@@ -15,6 +15,7 @@
  */
 
 import {
+  AnyValue,
   LogAttributes,
   LogRecord,
   Logger,
@@ -67,7 +68,7 @@
   const attributes: LogAttributes = {};
   for (const key in splat) {
     if (Object.prototype.hasOwnProperty.call(splat, key)) {
-      attributes[key] = splat[key];
+      attributes[key] = serializeAttribute(splat[key]);
     }
   }
   const logRecord: LogRecord = {
@@ -78,3 +79,37 @@
   };
   logger.emit(logRecord);
 }
+
+// Serialize objects and errors
+function serializeAttribute(value: any): AnyValue {
+  if (typeof value === 'object') {
+    if (value instanceof Error) {
+      return `[object Error] { message: "${value.message}", name: "${value.name}", stack: "${value.stack}"}`;
+    }
+    // TypedArrays
+    else if (
+      value instanceof Int8Array ||
+      value instanceof Uint8Array ||
+      value instanceof Uint8ClampedArray ||
+      value instanceof Int16Array ||
+      value instanceof Uint16Array ||
+      value instanceof Int32Array ||
+      value instanceof Uint32Array ||
+      value instanceof Float32Array ||
+      value instanceof Float64Array ||
+      value instanceof BigInt64Array ||
+      value instanceof BigUint64Array
+    ) {
+      return value as any; // TODO: Remove as any, when AnyValue type is updated to support TypedArrays
+    } else {
+      try {
+        return JSON.stringify(value);
+      } catch (err: unknown) {
+        // Failed to serialize, return string cast
+        return String(value);
+      }
+    }
+  }
+  // Return scalar and undefined values without serialization
+  return value;
+}

packages/winston-transport/test/openTelemetryTransport.test.ts

@@ -143,4 +143,71 @@ describe('OpenTelemetryTransportV3', () => {
       assert.strictEqual(logRecords[7].severityNumber, SeverityNumber.DEBUG);
     });
   });
+
+  it('serialized attibutes', () => {
+    const transport = new OpenTelemetryTransportV3();
+    transport.log(
+      {
+        message: 'test',
+        level: 'error',
+        someObject: { test: 'value' },
+        someArray: [{ test: 'value' }],
+        someError: new Error('testError'),
+        someInt8Array: new Int8Array(1),
+        someUint8Array: new Uint8Array(1),
+        someUint8ClampedArray: new Uint8ClampedArray(1),
+        someInt16Array: new Int16Array(1),
+        someUint16Array: new Uint16Array(1),
+        someInt32Array: new Int32Array(1),
+        someUint32Array: new Uint32Array(1),
+        someFloat32Array: new Float32Array(1),
+        someFloat64Array: new Float64Array(1),
+        someBigInt64Array: new BigInt64Array(1),
+        someBigUint64Array: new BigUint64Array(1),
+      },
+      () => {}
+    );
+    const logRecords = memoryLogExporter.getFinishedLogRecords();
+    assert.strictEqual(logRecords.length, 1);
+    assert.strictEqual(
+      logRecords[0].attributes['someObject'],
+      '{"test":"value"}'
+    );
+    assert.strictEqual(
+      logRecords[0].attributes['someArray'],
+      '[{"test":"value"}]'
+    );
+    assert.ok(
+      (logRecords[0].attributes['someError'] as string).startsWith(
+        '[object Error] { message: "testError", name: "Error", stack: "Error: testError'
+      ),
+      'Wrong error serialization'
+    );
+    assert.ok(logRecords[0].attributes['someInt8Array'] instanceof Int8Array);
+    assert.ok(logRecords[0].attributes['someUint8Array'] instanceof Uint8Array);
+    assert.ok(
+      logRecords[0].attributes['someUint8ClampedArray'] instanceof
+        Uint8ClampedArray
+    );
+    assert.ok(logRecords[0].attributes['someInt16Array'] instanceof Int16Array);
+    assert.ok(
+      logRecords[0].attributes['someUint16Array'] instanceof Uint16Array
+    );
+    assert.ok(logRecords[0].attributes['someInt32Array'] instanceof Int32Array);
+    assert.ok(
+      logRecords[0].attributes['someUint32Array'] instanceof Uint32Array
+    );
+    assert.ok(
+      logRecords[0].attributes['someFloat32Array'] instanceof Float32Array
+    );
+    assert.ok(
+      logRecords[0].attributes['someFloat64Array'] instanceof Float64Array
+    );
+    assert.ok(
+      logRecords[0].attributes['someBigInt64Array'] instanceof BigInt64Array
+    );
+    assert.ok(
+      logRecords[0].attributes['someBigUint64Array'] instanceof BigUint64Array
+    );
+  });
 });