Refactor SerializerOptions property to dynamically access JsonOptions from service provider

Co-authored-by: captainsafia <[email protected]>

Author: Copilot

src/Http/Http.Abstractions/src/Validation/ValidateContext.cs

@@ -63,10 +63,40 @@ public sealed class ValidateContext
 
     /// <summary>
     /// Gets or sets the JSON serializer options to use for property name formatting.
-    /// When set, property names in validation errors will be formatted according to the
+    /// When available, property names in validation errors will be formatted according to the
     /// PropertyNamingPolicy and JsonPropertyName attributes.
     /// </summary>
-    internal JsonSerializerOptions? SerializerOptions { get; set; }
+    internal JsonSerializerOptions? SerializerOptions 
+    { 
+        get
+        {
+            // If explicit options have been set, use those (primarily for testing)
+            if (_serializerOptions is not null)
+            {
+                return _serializerOptions;
+            }
+            
+            // Otherwise try to get them from DI
+            var jsonOptionsType = Type.GetType("Microsoft.AspNetCore.Http.Json.JsonOptions, Microsoft.AspNetCore.Http.Extensions");
+            if (jsonOptionsType is null)
+            {
+                return null;
+            }
+            
+            var jsonOptionsService = ValidationContext.GetService(jsonOptionsType);
+            if (jsonOptionsService is null)
+            {
+                return null;
+            }
+            
+            // Get the SerializerOptions property via reflection
+            var serializerOptionsProperty = jsonOptionsType.GetProperty("SerializerOptions");
+            return serializerOptionsProperty?.GetValue(jsonOptionsService) as JsonSerializerOptions;
+        }
+        set => _serializerOptions = value;
+    }
+    
+    private JsonSerializerOptions? _serializerOptions;
 
     internal void AddValidationError(string key, string[] error)
     {

src/Http/Routing/src/ValidationEndpointFilterFactory.cs

@@ -6,7 +6,6 @@
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Reflection;
-using Microsoft.AspNetCore.Http.Json;
 using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
@@ -56,9 +55,7 @@ public static EndpointFilterDelegate Create(EndpointFilterFactoryContext context
         {
             ValidateContext? validateContext = null;
 
-            // Get JsonOptions from DI if available
-            var jsonOptions = context.HttpContext.RequestServices.GetService<IOptions<JsonOptions>>();
-            var jsonSerializerOptions = jsonOptions?.Value?.SerializerOptions;
+            // JsonOptions will be retrieved directly by ValidateContext.SerializerOptions property
 
             for (var i = 0; i < context.Arguments.Count; i++)
             {
@@ -80,13 +77,6 @@ public static EndpointFilterDelegate Create(EndpointFilterFactoryContext context
                         ValidationOptions = options,
                         ValidationContext = validationContext
                     };
-                    
-                    // Set the serializer options via reflection as it's internal
-                    if (jsonSerializerOptions is not null)
-                    {
-                        var serializerOptionsProp = typeof(ValidateContext).GetProperty("SerializerOptions", BindingFlags.NonPublic | BindingFlags.Instance);
-                        serializerOptionsProp?.SetValue(validateContext, jsonSerializerOptions);
-                    }
                 }
                 else
                 {