Add SystemTextJsonSerializer to Cosmos client or else Cosmos SDK will use JSON.Net by default. (#90)

Author: StephenMolloy

src/CosmosDBSessionStateProviderAsync/CosmosDBSessionStateProviderAsync.cs

@@ -13,6 +13,8 @@ namespace Microsoft.AspNet.SessionState
     using System.Globalization;
     using System.IO;
     using System.IO.Compression;
+    using System.Text.Json.Serialization;
+    using System.Text.Json;
     using System.Threading;
     using System.Threading.Tasks;
     using System.Web;
@@ -859,6 +861,7 @@ internal static CosmosClientOptions ParseCosmosDBClientSettings(NameValueCollect
 
             var clientOptions = new CosmosClientOptions
             {
+                Serializer = new SystemTextJsonSerializer(null),
                 ConnectionMode = conMode,
                 RequestTimeout = new TimeSpan(0, 0, requestTimeout),
                 GatewayModeMaxConnectionLimit = maxConnectionLimit,

src/CosmosDBSessionStateProviderAsync/Microsoft.AspNet.SessionState.CosmosDBSessionStateProviderAsync.csproj

@@ -66,6 +66,7 @@
   <ItemGroup>
     <Compile Include="CosmosDBSessionStateProviderAsync.cs" />
     <Compile Include="SessionStateActionsConverter.cs" />
+    <Compile Include="SystemTextJsonSerializer.cs" />
     <Compile Include="TimeSpanConverter.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Resources\SR.Designer.cs">

src/CosmosDBSessionStateProviderAsync/SystemTextJsonSerializer.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See the License.txt file in the project root for full license information.
+
+namespace Microsoft.AspNet.SessionState
+{
+    using Microsoft.Azure.Cosmos;
+    using System.IO;
+    using System.Text.Json;
+
+    internal class SystemTextJsonSerializer : CosmosSerializer
+    {
+        private JsonSerializerOptions _opts;
+
+        public SystemTextJsonSerializer(JsonSerializerOptions jsonSerializerOptions)
+        {
+            _opts = jsonSerializerOptions ?? default(JsonSerializerOptions);
+        }
+
+        public override T FromStream<T>(Stream stream)
+        {
+            using (stream)
+            {
+                if (stream.CanSeek
+                       && stream.Length == 0)
+                {
+                    return default;
+                }
+
+                if (typeof(Stream).IsAssignableFrom(typeof(T)))
+                {
+                    return (T)(object)stream;
+                }
+
+                return JsonSerializer.Deserialize<T>(stream, _opts);
+            }
+        }
+
+        public override Stream ToStream<T>(T input)
+        {
+            MemoryStream ms = new MemoryStream();
+            JsonSerializer.Serialize(ms, input, input.GetType(), _opts);
+            ms.Position = 0;
+            return ms;
+        }
+    }
+}