From 2481fb6a8812f940f98199ea5e6b93707847ec4d Mon Sep 17 00:00:00 2001
From: Ruben Bartelink <ruben@bartelink.com>
Date: Mon, 3 Jan 2022 10:27:02 +0000
Subject: [PATCH] Fix UnionConverter

---
 CHANGELOG.md                                 | 3 +++
 src/FsCodec.SystemTextJson/UnionConverter.fs | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b7eabe..4cdc65f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,9 @@ The `Unreleased` section name is replaced by the expected version of next releas
 ## [Unreleased]
 
 ### Added
+
+- `SystemTextJson.UnionConverter`: Complete port of equivalent functionality in `NewtonsoftJson` equivalent [#59](https://github.com/jet/FsCodec/pull/59)
+
 ### Changed
 
 - `SystemTextJson`: Target `System.Text.Json` v `6.0.1` [#59](https://github.com/jet/FsCodec/pull/59)
diff --git a/src/FsCodec.SystemTextJson/UnionConverter.fs b/src/FsCodec.SystemTextJson/UnionConverter.fs
index d068ad1..f693910 100755
--- a/src/FsCodec.SystemTextJson/UnionConverter.fs
+++ b/src/FsCodec.SystemTextJson/UnionConverter.fs
@@ -131,7 +131,8 @@ type UnionConverter<'T>() =
             for fieldInfo, fieldValue in Seq.zip fieldInfos fieldValues do
                 if fieldValue <> null || options.DefaultIgnoreCondition <> Serialization.JsonIgnoreCondition.Always  then
                     writer.WritePropertyName(fieldInfo.Name)
-                    JsonSerializer.Serialize(writer, fieldValue, options)
+                    let element = JsonSerializer.SerializeToElement(fieldValue, fieldInfo.PropertyType, options)
+                    element.WriteTo writer
 
         writer.WriteEndObject()