Resolve external document dereference to OpenApiDocument using $ref to $id

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -24,7 +24,7 @@
     public class OpenApiDocument : IOpenApiSerializable, IOpenApiExtensible
     {
         /// <summary>
-        /// Related workspace containing OpenApiDocuments that are referenced in this document
+        /// Related workspace containing components that are referenced in a document
         /// </summary>
         public OpenApiWorkspace Workspace { get; set; }
 
@@ -128,7 +128,7 @@
 
             writer.WriteStartObject();
 
             // openApi;
             writer.WriteProperty(OpenApiConstants.OpenApi, "3.1.0");
 
             // jsonSchemaDialect

src/Microsoft.OpenApi/Reader/Services/OpenApiWorkspaceLoader.cs

@@ -28,7 +28,7 @@ internal async Task<OpenApiDiagnostic> LoadAsync(OpenApiReference reference,
         {
             _workspace.AddDocumentId(reference.ExternalResource, document.BaseUri);
             var version = diagnostic?.SpecificationVersion ?? OpenApiSpecVersion.OpenApi3_0;
-            _workspace.RegisterComponents(document, version);
+            _workspace.RegisterComponents(document);
             document.Workspace = _workspace;
 
             // Collect remote references by walking document

src/Microsoft.OpenApi/Reader/V2/OpenApiDocumentDeserializer.cs

@@ -252,7 +252,7 @@ public static OpenApiDocument LoadOpenApi(RootNode rootNode)
             FixRequestBodyReferences(openApiDoc);
 
             // Register components
-            openApiDoc.Workspace.RegisterComponents(openApiDoc, OpenApiSpecVersion.OpenApi2_0);
+            openApiDoc.Workspace.RegisterComponents(openApiDoc);
 
             return openApiDoc;
         }

src/Microsoft.OpenApi/Reader/V3/OpenApiDocumentDeserializer.cs

@@ -54,7 +54,7 @@ public static OpenApiDocument LoadOpenApi(RootNode rootNode)
             ParseMap(openApiNode, openApiDoc, _openApiFixedFields, _openApiPatternFields, openApiDoc);
 
             // Register components
-            openApiDoc.Workspace.RegisterComponents(openApiDoc, OpenApiSpecVersion.OpenApi3_0);
+            openApiDoc.Workspace.RegisterComponents(openApiDoc);
 
             return openApiDoc;
         }

src/Microsoft.OpenApi/Reader/V31/OpenApiDocumentDeserializer.cs

@@ -53,7 +53,7 @@ public static OpenApiDocument LoadOpenApi(RootNode rootNode)
             ParseMap(openApiNode, openApiDoc, _openApiFixedFields, _openApiPatternFields, openApiDoc);
 
             // Register components
-            openApiDoc.Workspace.RegisterComponents(openApiDoc, OpenApiSpecVersion.OpenApi3_1);
+            openApiDoc.Workspace.RegisterComponents(openApiDoc);
 
             return openApiDoc;
         }

src/Microsoft.OpenApi/Reader/V31/OpenApiV31Deserializer.cs

@@ -157,9 +157,11 @@ private static (string, string) GetReferenceIdAndExternalResource(string pointer
             string refId = !pointer.Contains('#') ? pointer : refSegments.Last();
 
             var isExternalResource = !refSegments.First().StartsWith("#");
-            string externalResource = isExternalResource
-                ? $"{refSegments.First()}/{refSegments[1].TrimEnd('#')}"
-                : null;
+            string externalResource = null;
+            if (isExternalResource && pointer.Contains('#'))
+            {
+                externalResource = $"{refSegments.First()}/{refSegments[1].TrimEnd('#')}";
+            }
 
             return (refId, externalResource);
         }

src/Microsoft.OpenApi/Services/OpenApiWorkspace.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using Microsoft.OpenApi.Extensions;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
 
@@ -54,6 +55,90 @@ public int ComponentsCount()
             return _IOpenApiReferenceableRegistry.Count + _artifactsRegistry.Count;
         }
 
+        /// <summary>
+        /// Registers a document's components into the workspace
+        /// </summary>
+        /// <param name="document"></param>
+        public void RegisterComponents(OpenApiDocument document)
+        {
+            if (document?.Components == null) return;
+
+            string baseUri = document.BaseUri + OpenApiConstants.ComponentsSegment;
+            string location;
+
+            // Register Schema
+            foreach (var item in document.Components.Schemas)
+            {
+                location = item.Value.Id ?? baseUri + ReferenceType.Schema.GetDisplayName() + "/" + item.Key;
+
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Parameters
+            foreach (var item in document.Components.Parameters)
+            {
+                location = baseUri + ReferenceType.Parameter.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Responses
+            foreach (var item in document.Components.Responses)
+            {
+                location = baseUri + ReferenceType.Response.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register RequestBodies
+            foreach (var item in document.Components.RequestBodies)
+            {
+                location = baseUri + ReferenceType.RequestBody.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Links
+            foreach (var item in document.Components.Links)
+            {
+                location = baseUri + ReferenceType.Link.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Callbacks
+            foreach (var item in document.Components.Callbacks)
+            {
+                location = baseUri + ReferenceType.Callback.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register PathItems
+            foreach (var item in document.Components.PathItems)
+            {
+                location = baseUri + ReferenceType.PathItem.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Examples
+            foreach (var item in document.Components.Examples)
+            {
+                location = baseUri + ReferenceType.Example.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register Headers
+            foreach (var item in document.Components.Headers)
+            {
+                location = baseUri + ReferenceType.Header.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+
+            // Register SecuritySchemes
+            foreach (var item in document.Components.SecuritySchemes)
+            {
+                location = baseUri + ReferenceType.SecurityScheme.GetDisplayName() + "/" + item.Key;
+                RegisterComponent(location, item.Value);
+            }
+        }
+
+
         /// <summary>
         /// Registers a component in the component registry.
         /// </summary>

test/Microsoft.OpenApi.Readers.Tests/V31Tests/OpenApiDocumentTests.cs

@@ -1,15 +1,17 @@
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
+using System.Threading.Tasks;
 using FluentAssertions;
 using Microsoft.OpenApi.Extensions;
-using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Models.References;
 using Microsoft.OpenApi.Reader;
 using Microsoft.OpenApi.Tests;
 using Microsoft.OpenApi.Writers;
+using Microsoft.OpenApi.Services;
 using Xunit;
+using System.Linq;
 
 namespace Microsoft.OpenApi.Readers.Tests.V31Tests
 {
@@ -392,7 +394,7 @@ public void ParseDocumentsWithReusablePathItemInWebhooksSucceeds()
     new OpenApiDiagnostic() { SpecificationVersion = OpenApiSpecVersion.OpenApi3_1 });
 
             var outputWriter = new StringWriter(CultureInfo.InvariantCulture);
-            var writer = new OpenApiJsonWriter(outputWriter, new() { InlineLocalReferences = true } );
+            var writer = new OpenApiJsonWriter(outputWriter, new() { InlineLocalReferences = true });
             actual.OpenApiDocument.SerializeAsV31(writer);
             var serialized = outputWriter.ToString();
         }
@@ -445,7 +447,7 @@ public void ParseDocumentWithPatternPropertiesInSchemaWorks()
                     }
                 }
             };
-            
+
             // Serialization
             var mediaType = result.OpenApiDocument.Paths["/example"].Operations[OperationType.Get].Responses["200"].Content["application/json"];
 
@@ -461,7 +463,7 @@ public void ParseDocumentWithPatternPropertiesInSchemaWorks()
       type: string
     prop3:
       type: string";
-            
+
             var actualMediaType = mediaType.SerializeAsYaml(OpenApiSpecVersion.OpenApi3_1);
 
             // Assert
@@ -484,5 +486,49 @@ public void ParseDocumentWithReferenceByIdGetsResolved()
             Assert.Equal("object", requestBodySchema.Type);
             Assert.Equal("string", parameterSchema.Type);
         }
+
+        [Fact]
+        public async Task ExternalDocumentDereferenceToOpenApiDocumentUsingJsonPointerWorks()
+        {
+            // Arrange
+            var path = Path.Combine(Directory.GetCurrentDirectory(), SampleFolderPath);
+
+            var settings = new OpenApiReaderSettings
+            {
+                LoadExternalRefs = true,
+                BaseUrl = new(path),
+            };
+
+            // Act
+            var result = await OpenApiDocument.LoadAsync(Path.Combine(SampleFolderPath, "externalRefByJsonPointer.yaml"), settings);
+            var responseSchema = result.OpenApiDocument.Paths["/resource"].Operations[OperationType.Get].Responses["200"].Content["application/json"].Schema;
+
+            // Assert
+            result.OpenApiDocument.Workspace.Contains("./externalResource.yaml");
+            responseSchema.Properties.Count.Should().Be(2); // reference has been resolved
+        }
+
+        [Fact]
+        public async Task ParseExternalDocumentDereferenceToOpenApiDocumentByIdWorks()
+        {
+            // Arrange
+            var path = Path.Combine(Directory.GetCurrentDirectory(), SampleFolderPath);
+
+            var settings = new OpenApiReaderSettings
+            {
+                LoadExternalRefs = true,
+                BaseUrl = new(path),
+            };
+
+            // Act
+            var result = await OpenApiDocument.LoadAsync(Path.Combine(SampleFolderPath, "externalRefById.yaml"), settings);
+            var doc2 = OpenApiDocument.Load(Path.Combine(SampleFolderPath, "externalResource.yaml")).OpenApiDocument;
+
+            var requestBodySchema = result.OpenApiDocument.Paths["/resource"].Operations[OperationType.Get].Parameters.First().Schema;
+            result.OpenApiDocument.Workspace.RegisterComponents(doc2);
+
+            // Assert
+            requestBodySchema.Properties.Count.Should().Be(2); // reference has been resolved
+        }
     }
 }

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiDocument/externalRefById.yaml

@@ -0,0 +1,14 @@
+openapi: 3.1.0
+info:
+  title: ReferenceById
+  version: 1.0.0
+paths:
+  /resource:
+    get:
+      parameters:
+        - name: id
+          in: query
+          required: true
+          schema:
+            $ref: 'https://example.com/schemas/user.json'
+components: {}

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiDocument/externalRefByJsonPointer.yaml

@@ -0,0 +1,15 @@
+openapi: 3.1.0
+info:
+  title: ReferenceById
+  version: 1.0.0
+paths:
+  /resource:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: './externalResource.yaml#/components/schemas/todo'
+components: {}