fix minimal api json options not being respected

README.md

@@ -115,6 +115,20 @@ In versions of Swashbuckle.AspNetCore prior to `5.0.0`, Swashbuckle would genera
 on the behavior of the [Newtonsoft.Json serializer][newtonsoft-json]. This made sense because that was the serializer that shipped with ASP.NET Core
 at the time. However, since ASP.NET Core 3.0, ASP.NET Core introduces a new serializer, [System.Text.Json (STJ)][system-text-json] out-of-the-box.
 
+If you find that the *STJ* options/attributes are not being honored, this may be because you are using a combination of Minimal APIs and MVC, which have separate JSON options.
+To force the OpenAPI document generation to use either set of JSON options you can use one of the following methods:
+
+```csharp
+services.AddSwaggerGen(c =>
+{
+    c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
+});
+// Then either:
+services.AddSwaggerGenMinimalApisJsonOptions();
+// or ...
+services.AddSwaggerGenMvcJsonOptions();
+```
+
 If you want to use Newtonsoft.Json instead, you need to install a separate package and explicitly opt-in. By default Swashbuckle.AspNetCore will assume
 you're using the System.Text.Json serializer and generate Schemas based on its behavior. If you're using Newtonsoft.Json then you'll need to install a
 separate Swashbuckle package, [Swashbuckle.AspNetCore.Newtonsoft][swashbuckle-aspnetcore-newtonsoft] to explicitly opt-in.

src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureMinimalApiSwaggerGenJsonOptions.cs

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.Http.Json;
+using Microsoft.Extensions.Options;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
+
+internal sealed class ConfigureMinimalApiSwaggerGenJsonOptions(IOptions<JsonOptions> jsonOptions) : IConfigureOptions<SwaggerGenJsonOptions>
+{
+    public void Configure(SwaggerGenJsonOptions options)
+    {
+        options.SerializerOptions = jsonOptions.Value.SerializerOptions;
+    }
+}

src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureMvcSwaggerGenJsonOptions.cs

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Options;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
+
+internal sealed class ConfigureMvcSwaggerGenJsonOptions(IOptions<JsonOptions> jsonOptions) : IConfigureOptions<SwaggerGenJsonOptions>
+{
+    public void Configure(SwaggerGenJsonOptions options)
+    {
+        options.SerializerOptions = jsonOptions.Value.JsonSerializerOptions;
+    }
+}

src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/ConfigureSwaggerGenJsonOptions.cs

@@ -0,0 +1,53 @@
+using System.Text.Json;
+using Microsoft.Extensions.Options;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
+
+internal sealed class ConfigureSwaggerGenJsonOptions : IPostConfigureOptions<SwaggerGenJsonOptions>
+{
+    private readonly IEnumerable<IConfigureOptions<Microsoft.AspNetCore.Http.Json.JsonOptions>> _minimalApiConfigureOptions;
+    private readonly IEnumerable<IPostConfigureOptions<Microsoft.AspNetCore.Http.Json.JsonOptions>> _minimalApiPostConfigureOptions;
+    private readonly Microsoft.AspNetCore.Http.Json.JsonOptions _minimalApiJsonOptions;
+    private readonly Microsoft.AspNetCore.Mvc.JsonOptions _mvcJsonOptions;
+
+    public ConfigureSwaggerGenJsonOptions(
+        IEnumerable<IConfigureOptions<Microsoft.AspNetCore.Http.Json.JsonOptions>> minimalApiConfigureOptions,
+        IEnumerable<IPostConfigureOptions<Microsoft.AspNetCore.Http.Json.JsonOptions>> minimalApiPostConfigureOptions,
+        IOptions<Microsoft.AspNetCore.Http.Json.JsonOptions> minimalApiJsonOptions,
+        IOptions<Microsoft.AspNetCore.Mvc.JsonOptions> mvcJsonOptions)
+    {
+        _minimalApiConfigureOptions = minimalApiConfigureOptions;
+        _minimalApiPostConfigureOptions = minimalApiPostConfigureOptions;
+        _minimalApiJsonOptions = minimalApiJsonOptions.Value;
+        _mvcJsonOptions = mvcJsonOptions.Value;
+    }
+
+    public void PostConfigure(string name, SwaggerGenJsonOptions options)
+    {
+        if (options.SerializerOptions != null)
+        {
+            return;
+        }
+
+        /*
+         * There is no surefire way to do this.
+         * However, both JsonOptions are defaulted in the same way.
+         * If neither is configured it makes no difference which one is chosen.
+         * If both are configured, then we just need to make a choice.
+         * As Minimal APIs are newer if someone is configuring them
+         * it's probably more likely that is what they're using.
+         * 
+         * If either JsonOptions is null we will try to create a new instance as
+         * a last resort as this is an expensive operation.
+         */
+
+        var serializerOptions = _mvcJsonOptions.JsonSerializerOptions;
+
+        if (_minimalApiConfigureOptions.Any() || _minimalApiPostConfigureOptions.Any())
+        {
+            serializerOptions = _minimalApiJsonOptions.SerializerOptions;
+        }
+
+        options.SerializerOptions = serializerOptions;
+    }
+}

src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/SwaggerGenJsonOptions.cs

@@ -0,0 +1,14 @@
+using System.Text.Json;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
+
+/// <summary>
+/// Configures the <see cref="JsonSerializerOptions"/> to be used by <see cref="JsonSerializerDataContractResolver"/>.
+/// </summary>
+public class SwaggerGenJsonOptions
+{
+    /// <summary>
+    /// Gets or sets the JSON serializer options to use.
+    /// </summary>
+    public JsonSerializerOptions SerializerOptions { get; set; }
+}

src/Swashbuckle.AspNetCore.SwaggerGen/DependencyInjection/SwaggerGenServiceCollectionExtensions.cs

@@ -1,9 +1,9 @@
-using System.Text.Json;
-using Microsoft.Extensions.ApiDescriptions;
+using Microsoft.Extensions.ApiDescriptions;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
 using Swashbuckle.AspNetCore.Swagger;
 using Swashbuckle.AspNetCore.SwaggerGen;
+using Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
 
 namespace Microsoft.Extensions.DependencyInjection;
 
@@ -29,10 +29,10 @@ public static IServiceCollection AddSwaggerGen(
         services.TryAddTransient(s => s.GetRequiredService<IOptions<SwaggerGeneratorOptions>>().Value);
         services.TryAddTransient<ISchemaGenerator, SchemaGenerator>();
         services.TryAddTransient(s => s.GetRequiredService<IOptions<SchemaGeneratorOptions>>().Value);
-        services.AddSingleton<JsonSerializerOptionsProvider>();
+        services.ConfigureOptions<ConfigureSwaggerGenJsonOptions>();
         services.TryAddSingleton<ISerializerDataContractResolver>(s =>
         {
-            var serializerOptions = s.GetRequiredService<JsonSerializerOptionsProvider>().Options;
+            var serializerOptions = s.GetRequiredService<IOptions<SwaggerGenJsonOptions>>().Value.SerializerOptions;
             return new JsonSerializerDataContractResolver(serializerOptions);
         });
 
@@ -44,41 +44,20 @@ public static IServiceCollection AddSwaggerGen(
         return services;
     }
 
-    public static void ConfigureSwaggerGen(
-        this IServiceCollection services,
-        Action<SwaggerGenOptions> setupAction)
+    public static IServiceCollection AddSwaggerGenMinimalApisJsonOptions(this IServiceCollection services)
     {
-        services.Configure(setupAction);
+        return services.ConfigureOptions<ConfigureMinimalApiSwaggerGenJsonOptions>();
     }
 
-    private sealed class JsonSerializerOptionsProvider
+    public static IServiceCollection AddSwaggerGenMvcJsonOptions(this IServiceCollection services)
     {
-        private JsonSerializerOptions _options;
-        private readonly IServiceProvider _serviceProvider;
-
-        public JsonSerializerOptionsProvider(IServiceProvider serviceProvider)
-        {
-            _serviceProvider = serviceProvider;
-        }
-
-        public JsonSerializerOptions Options => _options ??= ResolveOptions();
-
-        private JsonSerializerOptions ResolveOptions()
-        {
-            JsonSerializerOptions serializerOptions;
-
-            /*
-             * First try to get the options configured for MVC,
-             * then try to get the options configured for Minimal APIs if available,
-             * then try the default JsonSerializerOptions if available,
-             * otherwise create a new instance as a last resort as this is an expensive operation.
-             */
-            serializerOptions =
-                _serviceProvider.GetService<IOptions<AspNetCore.Mvc.JsonOptions>>()?.Value?.JsonSerializerOptions
-                ?? _serviceProvider.GetService<IOptions<AspNetCore.Http.Json.JsonOptions>>()?.Value?.SerializerOptions
-                ?? JsonSerializerOptions.Default;
+        return services.ConfigureOptions<ConfigureMvcSwaggerGenJsonOptions>();
+    }
 
-            return serializerOptions;
-        }
+    public static void ConfigureSwaggerGen(
+        this IServiceCollection services,
+        Action<SwaggerGenOptions> setupAction)
+    {
+        services.Configure(setupAction);
     }
 }

src/Swashbuckle.AspNetCore.SwaggerGen/PublicAPI/PublicAPI.Unshipped.txt

@@ -0,0 +1,4 @@
+Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection.SwaggerGenJsonOptions
+Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection.SwaggerGenJsonOptions.SerializerOptions.get -> System.Text.Json.JsonSerializerOptions
+Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection.SwaggerGenJsonOptions.SerializerOptions.set -> void
+Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection.SwaggerGenJsonOptions.SwaggerGenJsonOptions() -> void

src/Swashbuckle.AspNetCore.SwaggerGen/PublicAPI/net8.0/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
-
+static Microsoft.Extensions.DependencyInjection.SwaggerGenServiceCollectionExtensions.AddSwaggerGenMinimalApisJsonOptions(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
+static Microsoft.Extensions.DependencyInjection.SwaggerGenServiceCollectionExtensions.AddSwaggerGenMvcJsonOptions(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection

src/Swashbuckle.AspNetCore.SwaggerGen/PublicAPI/net9.0/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
-
+static Microsoft.Extensions.DependencyInjection.SwaggerGenServiceCollectionExtensions.AddSwaggerGenMinimalApisJsonOptions(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection
+static Microsoft.Extensions.DependencyInjection.SwaggerGenServiceCollectionExtensions.AddSwaggerGenMvcJsonOptions(this Microsoft.Extensions.DependencyInjection.IServiceCollection services) -> Microsoft.Extensions.DependencyInjection.IServiceCollection

test/Swashbuckle.AspNetCore.IntegrationTests/snapshots/VerifyTests.Swagger_IsValidJson_No_Startup_entryPointType=WebApi.Program_swaggerRequestUri=v1.DotNet8_0.verified.txt

@@ -988,12 +988,11 @@
       },
       "DateTimeKind": {
         "enum": [
-          0,
-          1,
-          2
+          "Unspecified",
+          "Utc",
+          "Local"
         ],
-        "type": "integer",
-        "format": "int32"
+        "type": "string"
       },
       "Fruit": {
         "type": "object",

test/Swashbuckle.AspNetCore.IntegrationTests/snapshots/VerifyTests.Swagger_IsValidJson_No_Startup_entryPointType=WebApi.Program_swaggerRequestUri=v1.DotNet9_0.verified.txt

@@ -988,12 +988,11 @@
       },
       "DateTimeKind": {
         "enum": [
-          0,
-          1,
-          2
+          "Unspecified",
+          "Utc",
+          "Local"
         ],
-        "type": "integer",
-        "format": "int32"
+        "type": "string"
       },
       "Fruit": {
         "type": "object",

test/Swashbuckle.AspNetCore.IntegrationTests/snapshots/VerifyTests.TypesAreRenderedCorrectly.DotNet8_0.verified.txt

@@ -988,12 +988,11 @@
       },
       "DateTimeKind": {
         "enum": [
-          0,
-          1,
-          2
+          "Unspecified",
+          "Utc",
+          "Local"
         ],
-        "type": "integer",
-        "format": "int32"
+        "type": "string"
       },
       "Fruit": {
         "type": "object",

test/Swashbuckle.AspNetCore.IntegrationTests/snapshots/VerifyTests.TypesAreRenderedCorrectly.DotNet9_0.verified.txt

@@ -988,12 +988,11 @@
       },
       "DateTimeKind": {
         "enum": [
-          0,
-          1,
-          2
+          "Unspecified",
+          "Utc",
+          "Local"
         ],
-        "type": "integer",
-        "format": "int32"
+        "type": "string"
       },
       "Fruit": {
         "type": "object",

test/Swashbuckle.AspNetCore.SwaggerGen.Test/Fixtures/DummyHostEnvironment.cs

@@ -0,0 +1,14 @@
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.FileProviders;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.Test.Fixtures;
+
+internal sealed class DummyHostEnvironment : IWebHostEnvironment
+{
+    public string WebRootPath { get; set; }
+    public IFileProvider WebRootFileProvider { get; set; }
+    public string ApplicationName { get; set; }
+    public IFileProvider ContentRootFileProvider { get; set; }
+    public string ContentRootPath { get; set; }
+    public string EnvironmentName { get; set; }
+}

test/Swashbuckle.AspNetCore.SwaggerGen.Test/SwaggerGenJsonOptionsTests.cs

@@ -0,0 +1,78 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using Swashbuckle.AspNetCore.SwaggerGen.DependencyInjection;
+using Swashbuckle.AspNetCore.SwaggerGen.Test.Fixtures;
+
+using MinimalApiJsonOptions = Microsoft.AspNetCore.Http.Json.JsonOptions;
+using MvcJsonOptions = Microsoft.AspNetCore.Mvc.JsonOptions;
+
+namespace Swashbuckle.AspNetCore.SwaggerGen.Test;
+
+public class SwaggerGenJsonOptionsTests
+{
+    [Fact]
+    public static void Ensure_SwaggerGenJsonOptions_Uses_MinimalApi_JsonOptions_When_Overridden()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<IWebHostEnvironment, DummyHostEnvironment>();
+        services.AddSwaggerGen();
+        services.AddMvcCore().AddJsonOptions(o => o.JsonSerializerOptions.AllowTrailingCommas = true);
+        services.AddSwaggerGenMinimalApisJsonOptions();
+
+        using var provider = services.BuildServiceProvider();
+
+        var minimalApiJsonOptions = provider.GetService<IOptions<MinimalApiJsonOptions>>().Value.SerializerOptions;
+        var swaggerGenSerializerOptions = provider.GetService<IOptions<SwaggerGenJsonOptions>>().Value.SerializerOptions;
+        Assert.Equal(minimalApiJsonOptions, swaggerGenSerializerOptions);
+    }
+
+    [Fact]
+    public static void Ensure_SwaggerGenJsonOptions_Uses_Mvc_JsonOptions_When_Overridden()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<IWebHostEnvironment, DummyHostEnvironment>();
+        services.AddSwaggerGen();
+        services.ConfigureHttpJsonOptions(o => o.SerializerOptions.AllowTrailingCommas = true);
+        services.AddSwaggerGenMvcJsonOptions();
+
+        using var provider = services.BuildServiceProvider();
+
+        var mvcJsonOptions = provider.GetService<IOptions<MvcJsonOptions>>().Value.JsonSerializerOptions;
+        var swaggerGenSerializerOptions = provider.GetService<IOptions<SwaggerGenJsonOptions>>().Value.SerializerOptions;
+        Assert.Equal(mvcJsonOptions, swaggerGenSerializerOptions);
+    }
+
+    [Fact]
+    public static void Ensure_SwaggerGenJsonOptions_Uses_Mvc_JsonOptions_When_Not_Using_Minimal_Apis()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<IWebHostEnvironment, DummyHostEnvironment>();
+        services.AddSwaggerGen();
+        services.AddMvcCore().AddJsonOptions(o => o.JsonSerializerOptions.AllowTrailingCommas = true);
+
+        using var provider = services.BuildServiceProvider();
+
+        var mvcJsonOptions = provider.GetService<IOptions<MvcJsonOptions>>().Value.JsonSerializerOptions;
+        var swaggerGenSerializerOptions = provider.GetService<IOptions<SwaggerGenJsonOptions>>().Value.SerializerOptions;
+        Assert.Equal(mvcJsonOptions, swaggerGenSerializerOptions);
+    }
+
+    [Fact]
+    public static void Ensure_SwaggerGenJsonOptions_Uses_MinimalApi_JsonOptions_When_Configured()
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton<IWebHostEnvironment, DummyHostEnvironment>();
+        services.AddSwaggerGen();
+        services.ConfigureHttpJsonOptions(o => o.SerializerOptions.AllowTrailingCommas = true);
+        services.AddMvcCore().AddJsonOptions(o => o.JsonSerializerOptions.AllowTrailingCommas = true);
+
+        using var provider = services.BuildServiceProvider();
+
+        var minimalApiJsonOptions = provider.GetService<IOptions<MinimalApiJsonOptions>>().Value.SerializerOptions;
+        var swaggerGenSerializerOptions = provider.GetService<IOptions<SwaggerGenJsonOptions>>().Value.SerializerOptions;
+        Assert.Equal(minimalApiJsonOptions, swaggerGenSerializerOptions);
+    }
+}

test/Swashbuckle.AspNetCore.SwaggerGen.Test/XmlComments/XmlCommentsDocumentFilterTests.cs

@@ -4,8 +4,8 @@
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.FileProviders;
 using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.SwaggerGen.Test.Fixtures;
 
 namespace Swashbuckle.AspNetCore.SwaggerGen.Test;
 
@@ -179,14 +179,4 @@ public void Ensure_IncludeXmlComments_Adds_Filter_To_Options()
         Assert.NotNull(options);
         Assert.Contains(options.DocumentFilters, x => x is XmlCommentsDocumentFilter);
     }
-
-    private sealed class DummyHostEnvironment : IWebHostEnvironment
-    {
-        public string WebRootPath { get; set; }
-        public IFileProvider WebRootFileProvider { get; set; }
-        public string ApplicationName { get; set; }
-        public IFileProvider ContentRootFileProvider { get; set; }
-        public string ContentRootPath { get; set; }
-        public string EnvironmentName { get; set; }
-    }
 }