Address PR comments.

src/AutoRest.CSharp.V3/Generation/Writers/ClientWriter.cs

@@ -265,38 +265,19 @@ namespace AutoRest.CSharp.V3.Generation.Writers
                         ObjectSerialization serialization = objectResponseBody.Serialization;
                         using (writer.Scope($"({responseVariable:D}, cancellationToken) =>", "{", "},"))
                         {
-                            switch (serialization)
-                            {
-                                case JsonSerialization jsonSerialization:
-                                    writer.WriteMethodDeserialization(jsonSerialization, async: false, ref valueVariable, responseVariable);
-                                    break;
-                                case XmlElementSerialization xmlSerialization:
-                                    writer.WriteMethodDeserialization(xmlSerialization, ref valueVariable, responseVariable);
-                                    break;
-                                default:
-                                    throw new NotSupportedException();
-                            }
+                            writer.WriteDeserializationForMethods(objectResponseBody.Serialization, async: false, ref valueVariable, responseVariable);
                             writer.Line($"return {valueVariable};");
                         }
 
                         using (writer.Scope($"async ({responseVariable:D}, cancellationToken) =>", newLine: false))
                         {
-                            switch (serialization)
-                            {
-                                case JsonSerialization jsonSerialization:
-                                    writer.WriteMethodDeserialization(jsonSerialization, async: true, ref valueVariable, responseVariable);
-                                    break;
-                                case XmlElementSerialization xmlSerialization:
-                                    writer.WriteMethodDeserialization(xmlSerialization, ref valueVariable, responseVariable);
-                                    break;
-                                default:
-                                    throw new NotSupportedException();
-                            }
+                            writer.WriteDeserializationForMethods(objectResponseBody.Serialization, async: true, ref valueVariable, responseVariable);
                             writer.Line($"return {valueVariable};");
                         }
                     }
                     else if (lroMethod.OriginalResponse.ResponseBody is StreamResponseBody)
                     {
+                        //TODO: https://github.com/Azure/autorest.csharp/issues/523
                         throw new NotSupportedException("Binary is not supported as message (not response) is required for ExtractResponseContent() call.");
                     }
                 }

src/AutoRest.CSharp.V3/Generation/Writers/CodeWriterExtensions.cs

@@ -5,6 +5,9 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using AutoRest.CSharp.V3.Generation.Types;
+using AutoRest.CSharp.V3.Output.Models.Serialization;
+using AutoRest.CSharp.V3.Output.Models.Serialization.Json;
+using AutoRest.CSharp.V3.Output.Models.Serialization.Xml;
 using AutoRest.CSharp.V3.Output.Models.Shared;
 
 namespace AutoRest.CSharp.V3.Generation.Writers
@@ -51,5 +54,19 @@ namespace AutoRest.CSharp.V3.Generation.Writers
                 writer.Line();
             }
         }
+
+        public static void WriteDeserializationForMethods(this CodeWriter writer, ObjectSerialization serialization, bool async,
+            ref string valueVariable, string responseVariable, string document = "document")
+        {
+            switch (serialization)
+            {
+                case JsonSerialization jsonSerialization:
+                    writer.WriteDeserializationForMethods(jsonSerialization, async, ref valueVariable, responseVariable);
+                    break;
+                case XmlElementSerialization xmlSerialization:
+                    writer.WriteDeserializationForMethods(xmlSerialization, ref valueVariable, responseVariable);
+                    break;
+            }
+        }
     }
 }

src/AutoRest.CSharp.V3/Generation/Writers/JsonCodeWriterExtensions.cs

@@ -384,22 +384,22 @@ namespace AutoRest.CSharp.V3.Generation.Writers
             _ => null
         };
 
-        public static void WriteMethodDeserialization(this CodeWriter writer, JsonSerialization serialization, bool async,
+        public static void WriteDeserializationForMethods(this CodeWriter writer, JsonSerialization serialization, bool async,
             ref string destination, string response, string document = "document")
         {
             writer.Append($"using var {document:D} = ");
             if (async)
             {
-                writer.Line($"await {typeof(JsonDocument)}.ParseAsync({response:D}.ContentStream, default, cancellationToken).ConfigureAwait(false);");
+                writer.Line($"await {typeof(JsonDocument)}.ParseAsync({response}.ContentStream, default, cancellationToken).ConfigureAwait(false);");
             }
             else
             {
-                writer.Line($"{typeof(JsonDocument)}.Parse({response:D}.ContentStream);");
+                writer.Line($"{typeof(JsonDocument)}.Parse({response}.ContentStream);");
             }
 
             writer.ToDeserializeCall(
                 serialization,
-                w => w.Append($"{document:D}.RootElement"),
+                w => w.Append($"{document}.RootElement"),
                 ref destination
             );
         }

src/AutoRest.CSharp.V3/Generation/Writers/RestClientWriter.cs

@@ -136,7 +136,7 @@ namespace AutoRest.CSharp.V3.Generation.Writers
                     WriteHeader(writer, header);
                 }
 
-                if (operation.Request.Body is RequestBody body)
+                if (operation.Request.Body is SchemaRequestBody body)
                 {
                     ParameterOrConstant value = body.Value;
                     switch (body.Serialization)
@@ -157,11 +157,12 @@ namespace AutoRest.CSharp.V3.Generation.Writers
                                 writerName: w => w.Append($"content.{nameof(XmlWriterContent.XmlWriter)}"));
                             writer.Line($"request.Content = content;");
                             break;
-                        case BinarySerialization _:
-                            writer.Line($"request.Content = {typeof(RequestContent)}.Create({WriteConstantOrParameter(value, ignoreNullability: true)});");
-                            break;
                     }
                 }
+                else if (operation.Request.Body is BinaryRequestBody binaryBody)
+                {
+                    writer.Line($"request.Content = {typeof(RequestContent)}.Create({WriteConstantOrParameter(binaryBody.Value, ignoreNullability: true)});");
+                }
 
                 writer.Line($"return message;");
             }
@@ -419,28 +420,20 @@ namespace AutoRest.CSharp.V3.Generation.Writers
                     string responseVariable = $"{messageVariable}.Response";
                     if (responseBody is ObjectResponseBody objectResponseBody)
                     {
-                        switch (objectResponseBody.Serialization)
-                        {
-                            case JsonSerialization jsonSerialization:
-                                writer.WriteMethodDeserialization(jsonSerialization, async, ref valueVariable, responseVariable);
-                                break;
-                            case XmlElementSerialization xmlSerialization:
-                                writer.WriteMethodDeserialization(xmlSerialization, ref valueVariable, responseVariable);
-                                break;
-                        }
+                        writer.WriteDeserializationForMethods(objectResponseBody.Serialization, async, ref valueVariable, responseVariable);
                     }
                     else if (responseBody is StreamResponseBody _)
                     {
-                        writer.Line($"var {valueVariable:D} = {messageVariable:D}.ExtractResponseContent();");
-                        using (writer.Scope($"if ({valueVariable:D} == null)"))
+                        writer.Line($"var {valueVariable:D} = {messageVariable}.ExtractResponseContent();");
+                        using (writer.Scope($"if ({valueVariable} == null)"))
                         {
                             if (async)
                             {
-                                writer.Line($"throw await clientDiagnostics.CreateRequestFailedExceptionAsync({responseVariable:D}).ConfigureAwait(false);");
+                                writer.Line($"throw await clientDiagnostics.CreateRequestFailedExceptionAsync({responseVariable}).ConfigureAwait(false);");
                             }
                             else
                             {
-                                writer.Line($"throw clientDiagnostics.CreateRequestFailedException({responseVariable:D});");
+                                writer.Line($"throw clientDiagnostics.CreateRequestFailedException({responseVariable});");
                             }
                         }
                     }

src/AutoRest.CSharp.V3/Generation/Writers/XmlCodeWriterExtensions.cs

@@ -180,8 +180,7 @@ namespace AutoRest.CSharp.V3.Generation.Writers
 
             string s = destination;
 
-            writer
-                .Line($"{type} {destination:D} = default;");
+            writer.Line($"{type} {destination:D} = default;");
 
             if (isElement)
             {
@@ -377,13 +376,13 @@ namespace AutoRest.CSharp.V3.Generation.Writers
             }
         }
 
-        public static void WriteMethodDeserialization(this CodeWriter writer, XmlElementSerialization serialization,
+        public static void WriteDeserializationForMethods(this CodeWriter writer, XmlElementSerialization serialization,
             ref string destination, string response, string document = "document")
         {
-            writer.Line($"var {document:D} = {typeof(XDocument)}.Load({response:D}.ContentStream, LoadOptions.PreserveWhitespace);");
+            writer.Line($"var {document:D} = {typeof(XDocument)}.Load({response}.ContentStream, LoadOptions.PreserveWhitespace);");
             writer.ToDeserializeCall(
                 serialization,
-                w => w.Append($"{document:D}"),
+                w => w.Append($"{document}"),
                 ref destination
             );
         }

src/AutoRest.CSharp.V3/Output/Builders/ClientBuilder.cs

@@ -268,8 +268,15 @@ namespace AutoRest.CSharp.V3.Output.Builders
                             break;
                         case ParameterLocation.Body:
                             Debug.Assert(httpRequestWithBody != null);
-                            var serialization = _serializationBuilder.Build(httpRequestWithBody.KnownMediaType, requestParameter.Schema, requestParameter.IsNullable());
-                            body = new RequestBody(constantOrParameter, serialization);
+                            if (httpRequestWithBody.KnownMediaType == KnownMediaType.Binary)
+                            {
+                                body = new BinaryRequestBody(constantOrParameter);
+                            }
+                            else
+                            {
+                                var serialization = _serializationBuilder.Build(httpRequestWithBody.KnownMediaType, requestParameter.Schema, requestParameter.IsNullable());
+                                body = new SchemaRequestBody(constantOrParameter, serialization);
+                            }
                             break;
                         case ParameterLocation.Uri:
                             if (defaultName == "$host")

src/AutoRest.CSharp.V3/Output/Builders/SerializationBuilder.cs

@@ -30,8 +30,6 @@ namespace AutoRest.CSharp.V3.Output.Builders
                     return BuildJsonObjectSerialization(objectSchema, type);
                 case KnownMediaType.Xml:
                     return BuildXmlObjectSerialization(objectSchema, type);
-                case KnownMediaType.Binary:
-                    return new BinarySerialization();
                 default:
                     throw new NotImplementedException(mediaType.ToString());
             }
@@ -45,8 +43,6 @@ namespace AutoRest.CSharp.V3.Output.Builders
                     return BuildSerialization(schema, isNullable);
                 case KnownMediaType.Xml:
                     return BuildXmlElementSerialization(schema, isNullable, schema.XmlName ?? schema.Name, true);
-                case KnownMediaType.Binary:
-                    return new BinarySerialization();
                 default:
                     throw new NotImplementedException(mediaType.ToString());
             }

src/AutoRest.CSharp.V3/Output/Models/Requests/BinaryRequestBody.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+namespace AutoRest.CSharp.V3.Output.Models.Requests
+{
+    internal class BinaryRequestBody : RequestBody
+    {
+        public BinaryRequestBody(ParameterOrConstant value)
+            : base(value)
+        {
+        }
+    }
+}

src/AutoRest.CSharp.V3/Output/Models/Requests/RequestBody.cs

@@ -1,19 +1,15 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-using AutoRest.CSharp.V3.Output.Models.Serialization;
-
 namespace AutoRest.CSharp.V3.Output.Models.Requests
 {
     internal class RequestBody
     {
         public ParameterOrConstant Value { get; }
-        public ObjectSerialization Serialization { get; }
 
-        public RequestBody(ParameterOrConstant value, ObjectSerialization serialization)
+        public RequestBody(ParameterOrConstant value)
         {
             Value = value;
-            Serialization = serialization;
         }
     }
 }

src/AutoRest.CSharp.V3/Output/Models/Requests/SchemaRequestBody.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using AutoRest.CSharp.V3.Output.Models.Serialization;
+
+namespace AutoRest.CSharp.V3.Output.Models.Requests
+{
+    internal class SchemaRequestBody : RequestBody
+    {
+        public ObjectSerialization Serialization { get; }
+
+        public SchemaRequestBody(ParameterOrConstant value, ObjectSerialization serialization)
+            : base(value)
+        {
+            Serialization = serialization;
+        }
+    }
+}

src/AutoRest.CSharp.V3/Output/Models/Serialization/BinarySerialization.cs

@@ -1,12 +0,0 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
-// Licensed under the MIT License.
-
-
-using AutoRest.CSharp.V3.Generation.Types;
-
-namespace AutoRest.CSharp.V3.Output.Models.Serialization.Xml
-{
-    internal class BinarySerialization : ObjectSerialization
-    {
-    }
-}