Better way to get product elements (#264)

* Better way to get product elements

Signed-off-by: Hongxin Liang <[email protected]>

* More comment

Signed-off-by: Hongxin Liang <[email protected]>

---------

Signed-off-by: Hongxin Liang <[email protected]>

Author: honnix

flytekit-scala_2.13/src/main/scala/org/flyte/flytekitscala/SdkLiteralTypes.scala

@@ -229,11 +229,7 @@ object SdkLiteralTypes {
 
   private def toStruct(product: Product): Struct = {
     def productToMap(product: Product): Map[String, Any] = {
-      // by spec getDeclaredFields is not ordered but in practice it works fine
-      // it's a lot better since Scala 2.13 because productElementNames was introduced
-      //   (product.productElementNames zip product.productIterator).toMap
-      product.getClass.getDeclaredFields
-        .map(_.getName)
+      productElementNames(product)
         .zip(product.productIterator.toList)
         .toMap
     }

flytekit-scala_2.13/src/main/scala/org/flyte/flytekitscala/SdkScalaType.scala

@@ -165,8 +165,7 @@ object SdkScalaType {
       ): ju.Map[String, SdkBindingData[_]] = {
         value match {
           case product: Product =>
-            value.getClass.getDeclaredFields
-              .map(_.getName)
+            productElementNames(product)
               .zip(product.productIterator.toSeq)
               .toMap
               .mapValues {

flytekit-scala_2.13/src/main/scala/org/flyte/flytekitscala/package.scala

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2023 Flyte Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.flyte
+
+package object flytekitscala {
+  private[flytekitscala] def productElementNames(
+      product: Product
+  ): List[String] = {
+    try {
+      // scala 2.13
+      product.getClass
+        .getMethod("productElementNames")
+        .invoke(product)
+        .asInstanceOf[Iterator[String]]
+        .toList
+    } catch {
+      case _: Throwable =>
+        // fall back to java's way, less reliable and with limitations
+        product.getClass.getDeclaredFields.map(_.getName).toList
+    }
+  }
+}