Read some System.Text.Json options

src/NSwag.Commands/Commands/Generation/OpenApiGeneratorCommandBase.cs

@@ -229,7 +229,7 @@ public async Task<TSettings> CreateSettingsAsync(AssemblyLoader.AssemblyLoader a
             }
             catch
             {
-                serializerSettings = AspNetCoreOpenApiDocumentGenerator.GetSystemTextJsonSettings();
+                serializerSettings = AspNetCoreOpenApiDocumentGenerator.GetSystemTextJsonSettings(serviceProvider);
             }
 #else
             var mvcJsonOptions = serviceProvider?.GetRequiredService<IOptions<MvcJsonOptions>>();

src/NSwag.Generation.AspNetCore/AspNetCoreOpenApiDocumentGenerator.cs

@@ -47,7 +47,7 @@ public async Task<OpenApiDocument> GenerateAsync(object serviceProvider)
             var typedServiceProvider = (IServiceProvider)serviceProvider;
 
             var mvcOptions = typedServiceProvider.GetRequiredService<IOptions<MvcOptions>>();
-            var settings = GetJsonSerializerSettings(typedServiceProvider) ?? GetSystemTextJsonSettings();
+            var settings = GetJsonSerializerSettings(typedServiceProvider) ?? GetSystemTextJsonSettings(typedServiceProvider);
 
             Settings.ApplySettings(settings, mvcOptions.Value);
 
@@ -127,15 +127,51 @@ public async Task<OpenApiDocument> GenerateAsync(ApiDescriptionGroupCollection a
 
         /// <summary>Gets the default serializer settings representing System.Text.Json.</summary>
         /// <returns>The settings.</returns>
-        public static JsonSerializerSettings GetSystemTextJsonSettings()
+        public static JsonSerializerSettings GetSystemTextJsonSettings(IServiceProvider serviceProvider)
         {
             // If the ASP.NET Core website does not use Newtonsoft.JSON we need to provide a 
             // contract resolver which reflects best the System.Text.Json behavior.
             // See https://github.com/RicoSuter/NSwag/issues/2243
-            return new JsonSerializerSettings
+            JsonSerializerSettings settings = new JsonSerializerSettings
             {
                 ContractResolver = new CamelCasePropertyNamesContractResolver()
             };
+
+#if NETSTANDARD2_0
+            if (serviceProvider == null)
+            {
+                return settings;
+            }
+
+            dynamic options = null;
+            try
+            {
+                var optionsAssembly = Assembly.Load(new AssemblyName("Microsoft.AspNetCore.Mvc.Core"));
+                var optionsType = typeof(IOptions<>).MakeGenericType(optionsAssembly.GetType("Microsoft.AspNetCore.Mvc.JsonOptions", true));
+                options = serviceProvider?.GetService(optionsType) as dynamic;
+            }
+            catch
+            {
+            }
+
+            if (!(options?.Value?.JsonSerializerOptions is System.Text.Json.JsonSerializerOptions jsonOptions))
+            {
+                return settings;
+            }
+
+            // StringEnumConverter
+            if (jsonOptions.Converters.Any(c => c is System.Text.Json.Serialization.JsonStringEnumConverter))
+            {
+                settings.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
+            }
+
+            if (jsonOptions.PropertyNamingPolicy == null)
+            {
+                // PocoCase
+                settings.ContractResolver = new DefaultContractResolver();
+            }
+#endif
+            return settings;
         }
 
         private List<Type> GenerateForControllers(

src/NSwag.Generation.AspNetCore/NSwag.Generation.AspNetCore.csproj

@@ -31,6 +31,9 @@
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Core" Version="1.0.3" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Formatters.Json" Version="1.0.3" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.Text.Json" Version="4.6.0"/>
+  </ItemGroup>
   <!--<ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp3.0' ">
     <PackageReference Include="Microsoft.AspNetCore.App" Version="3.0.0" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
@@ -42,4 +45,5 @@
   <ItemGroup>
     <ProjectReference Include="..\NSwag.Generation\NSwag.Generation.csproj" />
   </ItemGroup>
+
 </Project>

src/NSwag.Generation.AspNetCore3.Tests/NSwag.Generation.AspNetCore3.Tests.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="xunit" Version="2.3.0" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\NSwag.Generation.AspNetCore\NSwag.Generation.AspNetCore.csproj" />
+    <ProjectReference Include="..\NSwag.AspNetCore\NSwag.AspNetCore.csproj" />
+  </ItemGroup>
+</Project>

src/NSwag.Generation.AspNetCore3.Tests/SystemTextJsonTests.cs

@@ -0,0 +1,70 @@
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Serialization;
+using NSwag.AspNetCore;
+using NSwag.Generation.AspNetCore;
+using Xunit;
+
+namespace NSwag.Generation.AspNetCore3.Tests
+{
+    public class SystemTextJsonTests
+    {
+        [Fact]
+        public async Task SystemTextJsonEnumOptionIsRead()
+        {
+            var services = new ServiceCollection()
+                .AddLogging();
+
+            services.AddControllers()
+                .AddJsonOptions(opt => opt.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));
+            services.AddOpenApiDocument();
+            var sp = services.BuildServiceProvider();
+
+            var generator = sp.GetRequiredService<OpenApiDocumentRegistration>();
+            await generator.Generator.GenerateAsync(sp);
+            var settings =   generator.Generator.Settings;
+
+            Assert.Contains(settings.SerializerSettings.Converters,c =>  c is StringEnumConverter);
+        }
+
+        [Fact]
+        public async Task SystemTextJsonCaseOptionIsRead()
+        {
+            var services = new ServiceCollection()
+                .AddLogging();
+
+            services.AddControllers()
+                .AddJsonOptions(opt => opt.JsonSerializerOptions.PropertyNamingPolicy = null);
+            services.AddOpenApiDocument();
+            var sp = services.BuildServiceProvider();
+
+            var generator = sp.GetRequiredService<OpenApiDocumentRegistration>();
+            await generator.Generator.GenerateAsync(sp);
+            var settings =   generator.Generator.Settings;
+
+            Assert.IsType<DefaultContractResolver>(settings.SerializerSettings.ContractResolver);
+        }
+
+        [Fact]
+        public async Task SystemTextJsonOptionDefaultsWhenNotSet()
+        {
+            var services = new ServiceCollection()
+                .AddLogging();
+
+            services.AddControllers();
+            services.AddOpenApiDocument();
+            var sp = services.BuildServiceProvider();
+
+            var generator = sp.GetRequiredService<OpenApiDocumentRegistration>();
+            await generator.Generator.GenerateAsync(sp);
+            var settings =   generator.Generator.Settings;
+
+            Assert.IsType<CamelCasePropertyNamesContractResolver>(settings.SerializerSettings.ContractResolver);
+            Assert.DoesNotContain(settings.SerializerSettings.Converters,c =>  c is StringEnumConverter);
+        }
+    }
+}

src/NSwag.Min.sln

@@ -79,6 +79,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NSwag.Generation.Tests", "N
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NSwag.Sample.NETCore30", "NSwag.Sample.NETCore30\NSwag.Sample.NETCore30.csproj", "{A3A38972-E431-4EB2-92CA-F422791E2F74}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NSwag.Generation.AspNetCore3.Tests", "NSwag.Generation.AspNetCore3.Tests\NSwag.Generation.AspNetCore3.Tests.csproj", "{F9D9ADB3-B676-4332-A8B3-457A0521308A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -648,6 +650,24 @@ Global
 		{A3A38972-E431-4EB2-92CA-F422791E2F74}.ReleaseTypeScriptStrict|x64.Build.0 = Release|Any CPU
 		{A3A38972-E431-4EB2-92CA-F422791E2F74}.ReleaseTypeScriptStrict|x86.ActiveCfg = Release|Any CPU
 		{A3A38972-E431-4EB2-92CA-F422791E2F74}.ReleaseTypeScriptStrict|x86.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|x64.Build.0 = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Debug|x86.Build.0 = Debug|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|Any CPU.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|x64.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|x64.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|x86.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.Release|x86.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|Any CPU.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|Any CPU.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|x64.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|x64.Build.0 = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|x86.ActiveCfg = Release|Any CPU
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A}.ReleaseTypeScriptStrict|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -684,6 +704,7 @@ Global
 		{BBEBEC80-1E20-4C96-9A9F-2F50092E8FFC} = {A0338E8D-A4A3-4380-9FF7-1D0BDC260E31}
 		{3A6CA187-AD6F-438C-9E5B-B2771F75AF41} = {D8CC0D1C-8DAC-49FE-AA78-C028DC124DD5}
 		{A3A38972-E431-4EB2-92CA-F422791E2F74} = {A0338E8D-A4A3-4380-9FF7-1D0BDC260E31}
+		{F9D9ADB3-B676-4332-A8B3-457A0521308A} = {D8CC0D1C-8DAC-49FE-AA78-C028DC124DD5}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {98FCEEE2-A45C-41E7-B2ED-1B14755E9067}

src/NSwag.sln

@@ -164,6 +164,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NSwag.Sample.NETCore30", "N
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NSwag.Sample.NETCore31", "NSwag.Sample.NETCore31\NSwag.Sample.NETCore31.csproj", "{4BCF42CE-A289-4B6D-92DB-ED95F8ED4B19}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NSwag.Generation.AspNetCore3.Tests", "NSwag.Generation.AspNetCore3.Tests\NSwag.Generation.AspNetCore3.Tests.csproj", "{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -1052,6 +1054,24 @@ Global
 		{4BCF42CE-A289-4B6D-92DB-ED95F8ED4B19}.ReleaseTypeScriptStrict|x64.Build.0 = Release|Any CPU
 		{4BCF42CE-A289-4B6D-92DB-ED95F8ED4B19}.ReleaseTypeScriptStrict|x86.ActiveCfg = Release|Any CPU
 		{4BCF42CE-A289-4B6D-92DB-ED95F8ED4B19}.ReleaseTypeScriptStrict|x86.Build.0 = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|x64.Build.0 = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Debug|x86.Build.0 = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|x64.ActiveCfg = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|x64.Build.0 = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|x86.ActiveCfg = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.Release|x86.Build.0 = Release|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|Any CPU.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|Any CPU.Build.0 = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|x64.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|x64.Build.0 = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|x86.ActiveCfg = Debug|Any CPU
+		{9FA007B6-CBB0-4D88-B9A3-5D8AF7E02E79}.ReleaseTypeScriptStrict|x86.Build.0 = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE