Fix array circular references.

The fix is done by registering components before going deep into the recursion tree (where the leaves would be registered first).

Fixing this revealed an issue for default values for "local" attributes. Local attributes/parameter info should not apply to componetized schemas.

Author: desjoerd

src/OpenApi/src/Extensions/JsonNodeSchemaExtensions.cs

@@ -175,13 +175,16 @@ internal static void ApplyDefaultValue(this JsonNode schema, object? defaultValu
             return;
         }
 
+        var isReferencedSchema = schema[OpenApiConstants.SchemaId] is null;
+        var schemaAttribute = isReferencedSchema ? OpenApiConstants.RefDefaultAnnotation : OpenApiSchemaKeywords.DefaultKeyword;
+
         if (defaultValue is null)
         {
-            schema[OpenApiSchemaKeywords.DefaultKeyword] = null;
+            schema[schemaAttribute] = null;
         }
         else
         {
-            schema[OpenApiSchemaKeywords.DefaultKeyword] = JsonSerializer.SerializeToNode(defaultValue, jsonTypeInfo);
+            schema[schemaAttribute] = JsonSerializer.SerializeToNode(defaultValue, jsonTypeInfo);
         }
     }
 

src/OpenApi/src/Extensions/OpenApiDocumentExtensions.cs

@@ -17,25 +17,27 @@ internal static class OpenApiDocumentExtensions
     /// <returns>An <see cref="IOpenApiSchema"/> with a reference to the stored schema.</returns>
     public static IOpenApiSchema AddOpenApiSchemaByReference(this OpenApiDocument document, string schemaId, IOpenApiSchema schema)
     {
-        document.Components ??= new();
-        document.Components.Schemas ??= new Dictionary<string, IOpenApiSchema>();
-        document.Components.Schemas[schemaId] = schema;
+        // Make sure the document has a workspace,
+        // AddComponent will add it to the workspace when adding the component.
         document.Workspace ??= new();
-        var location = document.BaseUri + "/components/schemas/" + schemaId;
-        document.Workspace.RegisterComponentForDocument(document, schema, location);
+        // AddComponent will only add the schema if it doesn't already exist.
+        document.AddComponent(schemaId, schema);
 
         object? description = null;
         object? example = null;
+        object? defaultAnnotation = null;
         if (schema is OpenApiSchema actualSchema)
         {
             actualSchema.Metadata?.TryGetValue(OpenApiConstants.RefDescriptionAnnotation, out description);
             actualSchema.Metadata?.TryGetValue(OpenApiConstants.RefExampleAnnotation, out example);
+            actualSchema.Metadata?.TryGetValue(OpenApiConstants.RefDefaultAnnotation, out defaultAnnotation);
         }
 
         return new OpenApiSchemaReference(schemaId, document)
         {
             Description = description as string,
             Examples = example is JsonNode exampleJson ? [exampleJson] : null,
+            Default = defaultAnnotation as JsonNode,
         };
     }
 }

src/OpenApi/src/Schemas/OpenApiJsonSchema.Helpers.cs

@@ -355,7 +355,11 @@ public static void ReadProperty(ref Utf8JsonReader reader, string propertyName,
                 schema.Metadata ??= new Dictionary<string, object>();
                 schema.Metadata[OpenApiConstants.RefDescriptionAnnotation] = reader.GetString() ?? string.Empty;
                 break;
-
+            case OpenApiConstants.RefDefaultAnnotation:
+                reader.Read();
+                schema.Metadata ??= new Dictionary<string, object>();
+                schema.Metadata[OpenApiConstants.RefDefaultAnnotation] = ReadJsonNode(ref reader)!;
+                break;
             default:
                 reader.Skip();
                 break;

src/OpenApi/src/Services/OpenApiConstants.cs

@@ -13,6 +13,7 @@ internal static class OpenApiConstants
     internal const string DescriptionId = "x-aspnetcore-id";
     internal const string SchemaId = "x-schema-id";
     internal const string RefId = "x-ref-id";
+    internal const string RefDefaultAnnotation = "x-ref-default";
     internal const string RefDescriptionAnnotation = "x-ref-description";
     internal const string RefExampleAnnotation = "x-ref-example";
     internal const string RefKeyword = "$ref";

src/OpenApi/src/Services/Schemas/OpenApiSchemaService.cs

@@ -265,6 +265,20 @@ internal static IOpenApiSchema ResolveReferenceForSchema(OpenApiDocument documen
     {
         var schema = UnwrapOpenApiSchema(inputSchema);
 
+        if (inputSchema is OpenApiSchema && schema.Metadata is not null &&
+            !schema.Metadata.ContainsKey(OpenApiConstants.RefId) &&
+            schema.Metadata.TryGetValue(OpenApiConstants.SchemaId, out var referenceId) &&
+            referenceId is string referenceIdString)
+        {
+            var targetReferenceId = baseSchemaId is not null
+                ? $"{baseSchemaId}{referenceIdString}"
+                : referenceIdString;
+            if (!string.IsNullOrEmpty(targetReferenceId))
+            {
+                document.AddOpenApiSchemaByReference(targetReferenceId, schema);
+            }
+        }
+
         if (schema.Metadata is not null &&
             schema.Metadata.TryGetValue(OpenApiConstants.SchemaId, out var resolvedBaseSchemaId))
         {
@@ -347,14 +361,14 @@ internal static IOpenApiSchema ResolveReferenceForSchema(OpenApiDocument documen
         // we don't want to replace the top-level inline schema with a reference to itself. We want to replace
         // inline schemas to reference schemas for all schemas referenced in the top-level schema though (such as
         // `allOf`, `oneOf`, `anyOf`, `items`, `properties`, etc.) which is why `isTopLevel` is only set once.
-        if (schema is OpenApiSchema && schema.Metadata is not null &&
+        if (inputSchema is OpenApiSchema && schema.Metadata is not null &&
             !schema.Metadata.ContainsKey(OpenApiConstants.RefId) &&
-            schema.Metadata.TryGetValue(OpenApiConstants.SchemaId, out var referenceId) &&
-            referenceId is string referenceIdString)
+            schema.Metadata.TryGetValue(OpenApiConstants.SchemaId, out var referenceId2) &&
+            referenceId2 is string referenceIdString2)
         {
             var targetReferenceId = baseSchemaId is not null
-                ? $"{baseSchemaId}{referenceIdString}"
-                : referenceIdString;
+                ? $"{baseSchemaId}{referenceIdString2}"
+                : referenceIdString2;
             if (!string.IsNullOrEmpty(targetReferenceId))
             {
                 return document.AddOpenApiSchemaByReference(targetReferenceId, schema);

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiSchemaService/OpenApiSchemaService.RequestBodySchemas.cs

@@ -984,8 +984,9 @@ private void VerifyOptionalEnum(OpenApiDocument document)
         var property = properties["status"];
 
         Assert.NotNull(property);
-        Assert.Equal(3, property.Enum.Count);
-        Assert.Equal("Approved", property.Default.GetValue<string>());
+        var statusReference = Assert.IsType<OpenApiSchemaReference>(property);
+        Assert.Equal(3, statusReference.RecursiveTarget.Enum.Count);
+        Assert.Equal("Approved", statusReference.Default.GetValue<string>());
     }
 
     [ApiController]