[backend/asp] Improve validation error handling

Iceshrimp.Backend/Core/Extensions/MvcBuilderExtensions.cs

@@ -9,7 +9,6 @@ using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.Extensions.ObjectPool;
 using Microsoft.Extensions.Options;
 using Newtonsoft.Json;
-using JsonSerializer = System.Text.Json.JsonSerializer;
 
 namespace Iceshrimp.Backend.Core.Extensions;
 
@@ -82,9 +81,8 @@ public static class MvcBuilderExtensions
 				var message = details.Title ?? "One or more validation errors occurred.";
 				if (details.Detail != null)
 					message += $" - {details.Detail}";
-				var errors = JsonSerializer.Serialize(details.Errors);
 
-				throw new GracefulException(status, status.ToString(), message, errors);
+				throw new ValidationException(status, status.ToString(), message, details.Errors);
 			};
 		});
 

Iceshrimp.Backend/Core/Middleware/ErrorHandlerMiddleware.cs

@@ -76,37 +76,25 @@ public class ErrorHandlerMiddleware(
 				ctx.Response.StatusCode        = (int)ce.StatusCode;
 				ctx.Response.Headers.RequestId = ctx.TraceIdentifier;
 
+				// @formatter:off
 				if (isMastodon)
 					await ctx.Response.WriteAsJsonAsync(new MastodonErrorResponse
 					{
-						Error = verbosity >= ExceptionVerbosity.Basic
+						Error       = verbosity >= ExceptionVerbosity.Basic ? ce.Message : ce.StatusCode.ToString(),
-							? ce.Message
+						Description = verbosity >= ExceptionVerbosity.Basic ? ce.Details : null
-							: ce.StatusCode.ToString(),
-						Description = verbosity >= ExceptionVerbosity.Basic
-							? ce.Details
-							: null
 					});
 				else
 					await ctx.Response.WriteAsJsonAsync(new ErrorResponse
 					{
 						StatusCode = ctx.Response.StatusCode,
-						Error =
+						Error      = verbosity >= ExceptionVerbosity.Basic ? ce.Error : ce.StatusCode.ToString(),
-							verbosity >= ExceptionVerbosity.Basic
+						Message    = verbosity >= ExceptionVerbosity.Basic ? ce.Message : null,
-								? ce.Error
+						Details    = verbosity == ExceptionVerbosity.Full  ? ce.Details : null,
-								: ce.StatusCode.ToString(),
+						Errors     = verbosity == ExceptionVerbosity.Full  ? (ce as ValidationException)?.Errors : null,
-						Message =
+						Source     = verbosity == ExceptionVerbosity.Full  ? type : null,
-							verbosity >= ExceptionVerbosity.Basic
+						RequestId  = ctx.TraceIdentifier
-								? ce.Message
-								: null,
-						Details =
-							verbosity == ExceptionVerbosity.Full
-								? ce.Details
-								: null,
-						Source = verbosity == ExceptionVerbosity.Full
-							? type
-							: null,
-						RequestId = ctx.TraceIdentifier
 					});
+				// @formatter:on
 
 				var level = ce.SuppressLog ? LogLevel.Trace : LogLevel.Debug;
 
@@ -225,6 +213,16 @@ public class InstanceBlockedException(string uri, string? host = null)
 	public string Uri => uri;
 }
 
+public class ValidationException(
+	HttpStatusCode statusCode,
+	string error,
+	string message,
+	IDictionary<string, string[]> errors
+) : GracefulException(statusCode, error, message)
+{
+	public IDictionary<string, string[]> Errors => errors;
+}
+
 public enum ExceptionVerbosity
 {
 	[SuppressMessage("ReSharper", "UnusedMember.Global")]

Iceshrimp.Shared/Schemas/Web/ErrorResponse.cs

@@ -14,6 +14,9 @@ public class ErrorResponse
 	[JI(Condition = JsonIgnoreCondition.WhenWritingNull)]
 	public string? Details { get; set; }
 
+	[JI(Condition = JsonIgnoreCondition.WhenWritingNull)]
+	public IDictionary<string, string[]>? Errors { get; set; }
+
 	[JI(Condition = JsonIgnoreCondition.WhenWritingNull)]
 	public string? Source { get; set; }