Fix the media type issue with .NET 7 #1969

Author: alexeyzimarev

src/RestSharp/Parameters/Parameter.cs

@@ -21,7 +21,7 @@ public abstract record Parameter(string? Name, object? Value, ParameterType Type
     /// <summary>
     /// MIME content type of the parameter
     /// </summary>
-    public string? ContentType { get; protected init; }
+    public string ContentType { get; protected init; } = "text/plain";
 
     /// <summary>
     /// Return a human-readable representation of this parameter

src/RestSharp/Request/BodyExtensions.cs

@@ -15,6 +15,8 @@
 
 namespace RestSharp; 
 
+using System.Diagnostics.CodeAnalysis;
+
 static class BodyExtensions {
     public static bool TryGetBodyParameter(this RestRequest request, out BodyParameter? bodyParameter) {
         bodyParameter = request.Parameters.FirstOrDefault(p => p.Type == ParameterType.RequestBody) as BodyParameter;
@@ -23,5 +25,5 @@ public static bool TryGetBodyParameter(this RestRequest request, out BodyParamet
 
     public static bool HasFiles(this RestRequest request) => request.Files.Count > 0;
 
-    public static bool IsEmpty(this ParametersCollection? parameters) => parameters == null || parameters.Count == 0;
-}
+    public static bool IsEmpty([NotNullWhen(false)]this ParametersCollection? parameters) => parameters == null || parameters.Count == 0;
+}

src/RestSharp/Request/RequestContent.cs

@@ -151,11 +151,11 @@ void AddPostParameters(ParametersCollection? postParameters) {
 
         if (Content is MultipartFormDataContent mpContent) {
             // we got the multipart form already instantiated, just add parameters to it
-            foreach (var postParameter in postParameters!) {
+            foreach (var postParameter in postParameters) {
                 var parameterName = postParameter.Name!;
 
                 mpContent.Add(
-                    new StringContent(postParameter.Value!.ToString()!, _client.Options.Encoding, postParameter.ContentType),
+                    new StringContent(postParameter.Value?.ToString() ?? "", _client.Options.Encoding, postParameter.ContentType),
                     _request.MultipartFormQuoteParameters ? $"\"{parameterName}\"" : parameterName
                 );
             }

src/RestSharp/RestSharp.csproj

@@ -1,12 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">
     <ItemGroup Condition="$(TargetFramework) != 'net6.0' And $(TargetFramework) != 'net7.0'">
-        <PackageReference Include="System.Text.Json" Version="5.0.1" />
+        <PackageReference Include="System.Text.Json" Version="5.0.1"/>
     </ItemGroup>
     <ItemGroup>
-        <None Remove="RestSharp.csproj.DotSettings" />
+        <None Remove="RestSharp.csproj.DotSettings"/>
     </ItemGroup>
     <ItemGroup Condition="'$(TargetFramework)' == 'net471'">
-        <Reference Include="System.Net.Http" />
-        <Reference Include="System.Web" />
+        <Reference Include="System.Net.Http"/>
+        <Reference Include="System.Web"/>
+        <PackageReference Include="Nullable" Version="1.3.1" PrivateAssets="All"/>
+    </ItemGroup>
+    <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+        <PackageReference Include="Nullable" Version="1.3.1" PrivateAssets="All"/>
     </ItemGroup>
 </Project>

test/Directory.Build.props

@@ -3,7 +3,7 @@
     <PropertyGroup>
         <IsTestProject>true</IsTestProject>
         <IsPackable>false</IsPackable>
-        <TargetFrameworks>net472;net6.0</TargetFrameworks>
+        <TargetFrameworks>net472;net6.0;net7.0</TargetFrameworks>
         <Nullable>disable</Nullable>
     </PropertyGroup>
 

test/RestSharp.Tests.Integrated/RestSharp.Tests.Integrated.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <Nullable>disable</Nullable>
-        <TargetFrameworks>net6</TargetFrameworks>
+        <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
     </PropertyGroup>
     <ItemGroup>
         <ProjectReference Include="..\..\src\RestSharp.Serializers.Xml\RestSharp.Serializers.Xml.csproj"/>