Custom serialization for ValidationProblemDetails to allign paths in custom and mvc error messages (#19111)

* Rowrked #18771 with a more brute force solution

* Fixes class name. Adds unit test verifying behaviour.

* Corrected test name.

---------

Co-authored-by: Kenn Jacobsen <kja@umbraco.dk>
Co-authored-by: Andy Butland <abutland73@gmail.com>

src/Umbraco.Cms.Api.Management/Serialization/ConfigureUmbracoBackofficeJsonOptions.cs

@@ -33,6 +33,7 @@ public class ConfigureUmbracoBackofficeJsonOptions : IConfigureNamedOptions<Json
         options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
         options.JsonSerializerOptions.Converters.Add(new JsonUdiConverter());
         options.JsonSerializerOptions.Converters.Add(new JsonUdiRangeConverter());
+        options.JsonSerializerOptions.Converters.Add(new ValidationProblemDetailsConverter());
         options.JsonSerializerOptions.Converters.Add(new JsonObjectConverter());
 
         options.JsonSerializerOptions.TypeInfoResolver = _umbracoJsonTypeInfoResolver;

src/Umbraco.Cms.Api.Management/Serialization/ValidationProblemDetailsConverter.cs

@@ -0,0 +1,70 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Microsoft.AspNetCore.Mvc;
+using Umbraco.Cms.Core;
+using Umbraco.Extensions;
+
+namespace Umbraco.Cms.Api.Management.Serialization;
+
+/// <summary>
+/// Custom JSON converter registered via <see cref="ConfigureUmbracoBackofficeJsonOptions"/> to serialize <see cref="ValidationProblemDetails" /> to JSON.
+/// </summary>
+public sealed class ValidationProblemDetailsConverter : JsonConverter<ValidationProblemDetails>
+{
+    /// <inheritdoc />
+    public override ValidationProblemDetails? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        => null;
+
+    /// <inheritdoc />
+    public override void Write(Utf8JsonWriter writer, ValidationProblemDetails value, JsonSerializerOptions options)
+    {
+        writer.WriteStartObject();
+        writer.WriteString("type", value.Type);
+        writer.WriteString("title", value.Title);
+
+        if (value.Status.HasValue)
+        {
+            writer.WriteNumber("status", value.Status.Value);
+        }
+
+        if (value.Detail is not null)
+        {
+            writer.WriteString("detail", value.Detail);
+        }
+
+        if (value.Instance is not null)
+        {
+            writer.WriteString("instance", value.Instance);
+        }
+
+        if (value.Errors.Any())
+        {
+            writer.WritePropertyName("errors");
+            writer.WriteStartArray();
+
+            foreach (KeyValuePair<string, string[]> error in value.Errors)
+            {
+                writer.WriteStartObject();
+                writer.WritePropertyName($"$.{string.Join(".", error.Key.Split(Constants.CharArrays.Period).Select(s => s.ToFirstLowerInvariant()))}");
+                writer.WriteStartArray();
+
+                foreach (var errorDetails in error.Value)
+                {
+                    writer.WriteStringValue(errorDetails);
+                }
+
+                writer.WriteEndArray();
+                writer.WriteEndObject();
+            }
+
+            writer.WriteEndArray();
+        }
+
+        if (value.Extensions.TryGetValue("traceId", out var traceId) && traceId is string traceIdValue)
+        {
+            writer.WriteString("traceId", traceIdValue);
+        }
+
+        writer.WriteEndObject();
+    }
+}

tests/Umbraco.Tests.UnitTests/Umbraco.Cms.Api.Management/Serialization/BackOfficeSerializationTests.cs

@@ -52,6 +52,17 @@ public class BackOfficeSerializationTests
         }
     }
 
+    [Test]
+    public void Will_Serialize_ValidationProblemDetails_To_Casing_Aligned_With_Mvc()
+    {
+        var objectToSerialize = new TestValueWithValidationProblemDetail();
+
+        var json = JsonSerializer.Serialize(objectToSerialize, jsonOptions.JsonSerializerOptions);
+
+        var expectedJson = "{\"problemDetails\":{\"type\":\"Test type\",\"title\":\"Test title\",\"status\":400,\"detail\":\"Test detail\",\"instance\":\"Test instance\",\"errors\":[{\"$.testError1\":[\"Test error 1a\",\"Test error 1b\"]},{\"$.testError2\":[\"Test error 2a\"]},{\"$.testError3.testError3a\":[\"Test error 3b\"]}],\"traceId\":\"traceValue\"}}";
+        Assert.AreEqual(expectedJson, json);
+    }
+
     private static NestedJsonTestValue CreateNestedObject(int levels)
     {
         var root = new NestedJsonTestValue { Level = 1 };
@@ -77,4 +88,27 @@ public class BackOfficeSerializationTests
 
         public NestedJsonTestValue? Inner { get; set; }
     }
+
+    private class TestValueWithValidationProblemDetail
+    {
+        public ValidationProblemDetails ProblemDetails { get; set; } = new()
+        {
+            Title = "Test title",
+            Detail = "Test detail",
+            Status = 400,
+            Type = "Test type",
+            Instance = "Test instance",
+            Extensions =
+            {
+                ["traceId"] = "traceValue",
+                ["someOtherExtension"] = "someOtherExtensionValue",
+            },
+            Errors =
+            {
+                ["TestError1"] = ["Test error 1a", "Test error 1b"],
+                ["TestError2"] = ["Test error 2a"],
+                ["TestError3.TestError3a"] = ["Test error 3b"],
+            }
+        };
+    }
 }