Backport JsonSchemaExporter bugfix. (#5671)

* Backport JsonSchemaExporter bugfix.

* Address feedback.

Author: eiriktsarpalis

src/Shared/JsonSchemaExporter/JsonSchemaExporter.JsonSchema.cs

@@ -17,8 +17,8 @@ internal static partial class JsonSchemaExporter
     // https://github.com/dotnet/runtime/blob/50d6cad649aad2bfa4069268eddd16fd51ec5cf3/src/libraries/System.Text.Json/src/System/Text/Json/Schema/JsonSchema.cs
     private sealed class JsonSchema
     {
-        public static JsonSchema False { get; } = new(false);
-        public static JsonSchema True { get; } = new(true);
+        public static JsonSchema CreateFalseSchema() => new(false);
+        public static JsonSchema CreateTrueSchema() => new(true);
 
         public JsonSchema()
         {
@@ -467,7 +467,7 @@ public static void EnsureMutable(ref JsonSchema schema)
             switch (schema._trueOrFalse)
             {
                 case false:
-                    schema = new JsonSchema { Not = JsonSchema.True };
+                    schema = new JsonSchema { Not = JsonSchema.CreateTrueSchema() };
                     break;
                 case true:
                     schema = new JsonSchema();

src/Shared/JsonSchemaExporter/JsonSchemaExporter.cs

@@ -119,7 +119,7 @@ private static JsonSchema MapJsonSchemaCore(
         if (!ReflectionHelpers.IsBuiltInConverter(effectiveConverter))
         {
             // Return a `true` schema for types with user-defined converters.
-            return CompleteSchema(ref state, JsonSchema.True);
+            return CompleteSchema(ref state, JsonSchema.CreateTrueSchema());
         }
 
         if (parentPolymorphicTypeInfo is null && typeInfo.PolymorphismOptions is { DerivedTypes.Count: > 0 } polyOptions)
@@ -245,7 +245,7 @@ private static JsonSchema MapJsonSchemaCore(
                 if (effectiveUnmappedMemberHandling is JsonUnmappedMemberHandling.Disallow)
                 {
                     // Disallow unspecified properties.
-                    additionalProperties = JsonSchema.False;
+                    additionalProperties = JsonSchema.CreateFalseSchema();
                 }
 
                 if (typeDiscriminator is { } typeDiscriminatorPair)
@@ -435,7 +435,7 @@ private static JsonSchema MapJsonSchemaCore(
                 }
                 else
                 {
-                    schema = JsonSchema.True;
+                    schema = JsonSchema.CreateTrueSchema();
                 }
 
                 return CompleteSchema(ref state, schema);
@@ -578,7 +578,7 @@ private static string FormatJsonPointer(ReadOnlySpan<string> path)
 
     private static readonly Dictionary<Type, Func<JsonNumberHandling, JsonSchema>> _simpleTypeSchemaFactories = new()
     {
-        [typeof(object)] = _ => JsonSchema.True,
+        [typeof(object)] = _ => JsonSchema.CreateTrueSchema(),
         [typeof(bool)] = _ => new JsonSchema { Type = JsonSchemaType.Boolean },
         [typeof(byte)] = numberHandling => GetSchemaForNumericType(JsonSchemaType.Integer, numberHandling),
         [typeof(ushort)] = numberHandling => GetSchemaForNumericType(JsonSchemaType.Integer, numberHandling),
@@ -625,10 +625,10 @@ private static string FormatJsonPointer(ReadOnlySpan<string> path)
             Pattern = @"^\d+(\.\d+){1,3}$",
         },
 
-        [typeof(JsonDocument)] = _ => JsonSchema.True,
-        [typeof(JsonElement)] = _ => JsonSchema.True,
-        [typeof(JsonNode)] = _ => JsonSchema.True,
-        [typeof(JsonValue)] = _ => JsonSchema.True,
+        [typeof(JsonDocument)] = _ => JsonSchema.CreateTrueSchema(),
+        [typeof(JsonElement)] = _ => JsonSchema.CreateTrueSchema(),
+        [typeof(JsonNode)] = _ => JsonSchema.CreateTrueSchema(),
+        [typeof(JsonValue)] = _ => JsonSchema.CreateTrueSchema(),
         [typeof(JsonObject)] = _ => new JsonSchema { Type = JsonSchemaType.Object },
         [typeof(JsonArray)] = _ => new JsonSchema { Type = JsonSchemaType.Array },
     };

test/Shared/JsonSchemaExporter/JsonSchemaExporterTests.cs

@@ -13,6 +13,7 @@
 using System.Xml.Linq;
 #endif
 using Xunit;
+using static Microsoft.Extensions.AI.JsonSchemaExporter.TestTypes;
 
 #pragma warning disable SA1402 // File may only contain a single type
 
@@ -86,6 +87,38 @@ public void CanGenerateXElementSchema()
     }
 #endif
 
+#if !NET9_0 // Disable until https://github.com/dotnet/runtime/pull/109954 gets backported
+    [Fact]
+    public void TransformSchemaNode_PropertiesWithCustomConverters()
+    {
+        // Regression test for https://github.com/dotnet/runtime/issues/109868
+        List<(Type? parentType, string? propertyName, Type type)> visitedNodes = new();
+        JsonSchemaExporterOptions exporterOptions = new()
+        {
+            TransformSchemaNode = (ctx, schema) =>
+            {
+#if NET9_0_OR_GREATER
+                visitedNodes.Add((ctx.PropertyInfo?.DeclaringType, ctx.PropertyInfo?.Name, ctx.TypeInfo.Type));
+#else
+                visitedNodes.Add((ctx.DeclaringType, ctx.PropertyInfo?.Name, ctx.TypeInfo.Type));
+#endif
+                return schema;
+            }
+        };
+
+        List<(Type? parentType, string? propertyName, Type type)> expectedNodes =
+        [
+            (typeof(ClassWithPropertiesUsingCustomConverters), "Prop1", typeof(ClassWithPropertiesUsingCustomConverters.ClassWithCustomConverter1)),
+                (typeof(ClassWithPropertiesUsingCustomConverters), "Prop2", typeof(ClassWithPropertiesUsingCustomConverters.ClassWithCustomConverter2)),
+                (null, null, typeof(ClassWithPropertiesUsingCustomConverters)),
+            ];
+
+        Options.GetJsonSchemaAsNode(typeof(ClassWithPropertiesUsingCustomConverters), exporterOptions);
+
+        Assert.Equal(expectedNodes, visitedNodes);
+    }
+#endif
+
     [Fact]
     public void TreatNullObliviousAsNonNullable_True_DoesNotImpactObjectType()
     {

test/Shared/JsonSchemaExporter/TestTypes.cs

@@ -1164,6 +1164,29 @@ public readonly struct StructDictionary<TKey, TValue>(IEnumerable<KeyValuePair<T
         IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable)_dictionary).GetEnumerator();
     }
 
+    public class ClassWithPropertiesUsingCustomConverters
+    {
+        [JsonPropertyOrder(0)]
+        public ClassWithCustomConverter1? Prop1 { get; set; }
+        [JsonPropertyOrder(1)]
+        public ClassWithCustomConverter2? Prop2 { get; set; }
+
+        [JsonConverter(typeof(CustomConverter<ClassWithCustomConverter1>))]
+        public class ClassWithCustomConverter1;
+
+        [JsonConverter(typeof(CustomConverter<ClassWithCustomConverter2>))]
+        public class ClassWithCustomConverter2;
+
+        public sealed class CustomConverter<T> : JsonConverter<T>
+        {
+            public override T? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+                => default;
+
+            public override void Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
+                => writer.WriteNullValue();
+        }
+    }
+
     [JsonSerializable(typeof(object))]
     [JsonSerializable(typeof(bool))]
     [JsonSerializable(typeof(byte))]
@@ -1248,6 +1271,7 @@ public readonly struct StructDictionary<TKey, TValue>(IEnumerable<KeyValuePair<T
     [JsonSerializable(typeof(PocoCombiningPolymorphicTypeAndDerivedTypes))]
     [JsonSerializable(typeof(ClassWithComponentModelAttributes))]
     [JsonSerializable(typeof(ClassWithOptionalObjectParameter))]
+    [JsonSerializable(typeof(ClassWithPropertiesUsingCustomConverters))]
     // Collection types
     [JsonSerializable(typeof(int[]))]
     [JsonSerializable(typeof(List<bool>))]