Repro for issue 1224: Validate

src/Examples/JsonApiDotNetCoreExample/Controllers/PostItsController.cs

@@ -0,0 +1,11 @@
+using JsonApiDotNetCore.Controllers.Annotations;
+using Microsoft.AspNetCore.Mvc;
+
+namespace JsonApiDotNetCoreExample.Controllers;
+
+[ApiController]
+[DisableRoutingConvention]
+[Route("api/v1/postIts")]
+public partial class PostItsController
+{
+}

src/Examples/JsonApiDotNetCoreExample/Data/AppDbContext.cs

@@ -10,6 +10,7 @@ namespace JsonApiDotNetCoreExample.Data;
 public sealed class AppDbContext : DbContext
 {
     public DbSet<TodoItem> TodoItems => Set<TodoItem>();
+    public DbSet<PostIt> PostIts => Set<PostIt>();
 
     public AppDbContext(DbContextOptions<AppDbContext> options)
         : base(options)

src/Examples/JsonApiDotNetCoreExample/Models/PostIt.cs

@@ -0,0 +1,29 @@
+using System.ComponentModel.DataAnnotations;
+using JsonApiDotNetCore.Resources;
+using JsonApiDotNetCore.Resources.Annotations;
+
+namespace JsonApiDotNetCoreExample.Models;
+
+[Resource]
+public class PostIt : Identifiable<int>
+{
+    [Attr]
+    [Required]
+    public bool Actif { get; set; }
+
+    [Attr]
+    [Required]
+    public DateTime Date { get; set; }
+
+    [Attr]
+    [MaxLength(2, ErrorMessage = "Error")]
+    public string Message { get; set; }
+
+    [Attr]
+    [MaxLength(2)]
+    public string OtherMessage { get; set; }
+
+    [Attr]
+    [Required]
+    public string RefOperateur { get; set; }
+}

src/Examples/JsonApiDotNetCoreExample/Program.cs

@@ -3,6 +3,7 @@
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Diagnostics;
 using JsonApiDotNetCoreExample.Data;
+using JsonApiDotNetCoreExample.Models;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection.Extensions;
@@ -98,5 +99,21 @@ static async Task CreateDatabaseAsync(IServiceProvider serviceProvider)
     await using AsyncServiceScope scope = serviceProvider.CreateAsyncScope();
 
     var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+
+    await dbContext.Database.EnsureDeletedAsync();
     await dbContext.Database.EnsureCreatedAsync();
+
+    var postIt = new PostIt
+    {
+        Id = 835405,
+        Actif = true,
+        Date = DateTime.UtcNow,
+        Message = "ab",
+        OtherMessage = "cd",
+        RefOperateur = "some-ref"
+    };
+
+    dbContext.PostIts.Add(postIt);
+
+    await dbContext.SaveChangesAsync();
 }

src/JsonApiDotNetCore/Errors/UnsuccessfulActionResultException.cs

@@ -1,6 +1,7 @@
 using System.Net;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.Serialization.Objects;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 
 namespace JsonApiDotNetCore.Errors;
@@ -20,20 +21,35 @@ public UnsuccessfulActionResultException(HttpStatusCode status)
     }
 
     public UnsuccessfulActionResultException(ProblemDetails problemDetails)
-        : base(ToError(problemDetails))
+        : base(ToErrorObjects(problemDetails))
     {
     }
 
-    private static ErrorObject ToError(ProblemDetails problemDetails)
+    private static IEnumerable<ErrorObject> ToErrorObjects(ProblemDetails problemDetails)
     {
         ArgumentGuard.NotNull(problemDetails);
 
         HttpStatusCode status = problemDetails.Status != null ? (HttpStatusCode)problemDetails.Status.Value : HttpStatusCode.InternalServerError;
 
+        if (problemDetails is HttpValidationProblemDetails validationProblemDetails && validationProblemDetails.Errors.Any())
+        {
+            foreach (string errorMessage in validationProblemDetails.Errors.SelectMany(pair => pair.Value))
+            {
+                yield return ToErrorObject(status, validationProblemDetails, errorMessage);
+            }
+        }
+        else
+        {
+            yield return ToErrorObject(status, problemDetails, problemDetails.Detail);
+        }
+    }
+
+    private static ErrorObject ToErrorObject(HttpStatusCode status, ProblemDetails problemDetails, string detail)
+    {
         var error = new ErrorObject(status)
         {
             Title = problemDetails.Title,
-            Detail = problemDetails.Detail
+            Detail = detail
         };
 
         if (!string.IsNullOrWhiteSpace(problemDetails.Instance))