Let JsonException bubble through problem details in minimal APIs

src/Http/Http.Extensions/src/RequestDelegateFactory.cs

@@ -1422,6 +1422,28 @@ private static Expression AddResponseWritingToMethodCall(Expression methodCall,
                 {
                     Log.InvalidJsonRequestBody(httpContext, parameterTypeName, parameterName, ex, throwOnBadRequest);
                     httpContext.Response.StatusCode = StatusCodes.Status400BadRequest;
+
+                    var problemDetailsService = httpContext.RequestServices.GetService<IProblemDetailsService>();
+                    if (problemDetailsService is not null)
+                    {
+                        IEnumerable<KeyValuePair<string, string[]>> errors =
+                        [
+                            new KeyValuePair<string, string[]>(ex.Path ?? string.Empty, [ex.Message]),
+                        ];
+
+                        var problemDetailsContext = new ProblemDetailsContext()
+                        {
+                            HttpContext = httpContext,
+                            Exception = ex,
+                            ProblemDetails = new HttpValidationProblemDetails(errors)
+                            {
+                                Status = StatusCodes.Status400BadRequest,
+                            },
+                        };
+
+                        _ = await problemDetailsService.TryWriteAsync(problemDetailsContext);
+                    }
+
                     return (null, false);
                 }
             }

src/Mvc/test/Mvc.FunctionalTests/SimpleWithWebApplicationBuilderTests.cs

@@ -291,4 +291,16 @@ public async Task FileUpload_Fails_WithoutAntiforgeryToken()
         // Assert
         await response.AssertStatusCodeAsync(HttpStatusCode.BadRequest);
     }
+
+    [Theory]
+    [InlineData("/post-required-minimal")]
+    [InlineData("/post-required-mvc")]
+    public async Task PostWithRequiredProperty(string endpoint)
+    {
+        var response = await Client.PostAsJsonAsync(endpoint, new { });
+        var responseString = await response.Content.ReadAsStringAsync();
+        Assert.Matches("""
+            {"type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"One or more validation errors occurred\.","status":400,"errors":{"\$":\["JSON deserialization for type 'ModelWithRequiredProperty' was missing required properties including: 'prop'\."]},"traceId":".+?"}
+            """, responseString);
+    }
 }

src/Mvc/test/WebSites/SimpleWebSiteWithWebApplicationBuilder/Program.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel.DataAnnotations;
 using Microsoft.AspNetCore.Mvc;
 
 using static Microsoft.AspNetCore.Http.Results;
@@ -9,6 +10,7 @@
 
 builder.Services.AddControllers();
 builder.Services.AddAntiforgery();
+builder.Services.AddProblemDetails();
 
 var app = builder.Build();
 
@@ -53,6 +55,8 @@
     return uploadStream.Length;
 });
 
+app.MapPost("/post-required-minimal", string (ModelWithRequiredProperty model) => $"Hello {model.Prop}");
+
 app.Run();
 
 record Person(string Name, int Age);
@@ -63,6 +67,19 @@ public class MyController : ControllerBase
     public string Greet() => $"Hello human";
 }
 
+[ApiController]
+public class MyApiController
+{
+    [HttpPost("/post-required-mvc")]
+    public string PostModel(ModelWithRequiredProperty model) => $"Hello {model.Prop}";
+}
+
+public class ModelWithRequiredProperty
+{
+    [Required]
+    public required string Prop { get; set; }
+}
+
 namespace SimpleWebSiteWithWebApplicationBuilder
 {
     public partial class Program