Add requestbody references as parameter references in v2 serialization

Author: millicentachieng

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -160,7 +160,7 @@ public void SerializeAsV2(IOpenApiWriter writer)
             // paths
             writer.WriteRequiredObject(OpenApiConstants.Paths, Paths, (w, p) => p.SerializeAsV2(w));
 
-            // If references have been inlined we don't need the to render the components section
+            // If references have been inlined we don't need to render the components section
             // however if they have cycles, then we will need a component rendered
             if (writer.GetSettings().InlineLocalReferences)
             {
@@ -208,9 +208,17 @@ public void SerializeAsV2(IOpenApiWriter writer)
                     });
             }
             // parameters
+            IDictionary<string, OpenApiParameter> parameters =  Components?.Parameters;
+            if (Components?.RequestBodies != null)
+            {
+                foreach (var requestBody in Components.RequestBodies)
+                {
+                    parameters.Add(requestBody.Key, requestBody.Value.ConvertToBodyParameter());
+                }
+            }
             writer.WriteOptionalMap(
                 OpenApiConstants.Parameters,
-                Components?.Parameters,
+                parameters,
                 (w, key, component) =>
                 {
                     if (component.Reference != null &&

src/Microsoft.OpenApi/Models/OpenApiOperation.cs

@@ -275,28 +275,18 @@ public void SerializeAsV2(IOpenApiWriter writer)
                     }
                     else
                     {
-                        var content = RequestBody.Content.Values.FirstOrDefault();
-
-                        var bodyParameter = new OpenApiBodyParameter
-                        {
-                            Description = RequestBody.Description,
-                            // V2 spec actually allows the body to have custom name.
-                            // To allow round-tripping we use an extension to hold the name
-                            Name = "body",
-                            Schema = content?.Schema ?? new OpenApiSchema(),
-                            Required = RequestBody.Required,
-                            Extensions = RequestBody.Extensions.ToDictionary(k => k.Key, v => v.Value)  // Clone extensions so we can remove the x-bodyName extensions from the output V2 model.
-                        };
-
-                        if (bodyParameter.Extensions.ContainsKey(OpenApiConstants.BodyName))
-                        {
-                            bodyParameter.Name = (RequestBody.Extensions[OpenApiConstants.BodyName] as OpenApiString)?.Value ?? "body";
-                            bodyParameter.Extensions.Remove(OpenApiConstants.BodyName);
-                        }
-
-                        parameters.Add(bodyParameter);
+                        parameters.Add(RequestBody.ConvertToBodyParameter());
                     }
                 }
+                else if (RequestBody.Reference != null)
+                {
+                    parameters.Add(
+                        new OpenApiParameter 
+                        { 
+                            UnresolvedReference = true,
+                            Reference = RequestBody.Reference
+                        });
+                }
             }
 
             if (Responses != null)

src/Microsoft.OpenApi/Models/OpenApiReference.cs

@@ -214,31 +214,17 @@ private string GetExternalReferenceV2()
 
         private string GetReferenceTypeNameAsV2(ReferenceType type)
         {
-            switch (type)
+            return type switch
             {
-                case ReferenceType.Schema:
-                    return OpenApiConstants.Definitions;
-
-                case ReferenceType.Parameter:
-                    return OpenApiConstants.Parameters;
-
-                case ReferenceType.Response:
-                    return OpenApiConstants.Responses;
-
-                case ReferenceType.Header:
-                    return OpenApiConstants.Headers;
-
-                case ReferenceType.Tag:
-                    return OpenApiConstants.Tags;
-
-                case ReferenceType.SecurityScheme:
-                    return OpenApiConstants.SecurityDefinitions;
-
-                default:
-                    // If the reference type is not supported in V2, simply return null
-                    // to indicate that the reference is not pointing to any object.
-                    return null;
-            }
+                ReferenceType.Schema => OpenApiConstants.Definitions,
+                ReferenceType.Parameter or ReferenceType.RequestBody => OpenApiConstants.Parameters,
+                ReferenceType.Response => OpenApiConstants.Responses,
+                ReferenceType.Header => OpenApiConstants.Headers,
+                ReferenceType.Tag => OpenApiConstants.Tags,
+                ReferenceType.SecurityScheme => OpenApiConstants.SecurityDefinitions,
+                _ => null,// If the reference type is not supported in V2, simply return null
+                          // to indicate that the reference is not pointing to any object.
+            };
         }
     }
 }

src/Microsoft.OpenApi/Models/OpenApiRequestBody.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. 
 
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.OpenApi.Any;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Writers;
@@ -144,5 +145,25 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
         {
             // RequestBody object does not exist in V2.
         }
+
+        internal OpenApiBodyParameter ConvertToBodyParameter()
+        {
+            var bodyParameter = new OpenApiBodyParameter
+            {
+                Description = Description,
+                // V2 spec actually allows the body to have custom name.
+                // To allow round-tripping we use an extension to hold the name
+                Name = "body",
+                Schema = Content.Values.FirstOrDefault()?.Schema ?? new OpenApiSchema(),
+                Required = Required,
+                Extensions = Extensions.ToDictionary(k => k.Key, v => v.Value)  // Clone extensions so we can remove the x-bodyName extensions from the output V2 model.
+            };
+            if (bodyParameter.Extensions.ContainsKey(OpenApiConstants.BodyName))
+            {
+                bodyParameter.Name = (Extensions[OpenApiConstants.BodyName] as OpenApiString)?.Value ?? "body";
+                bodyParameter.Extensions.Remove(OpenApiConstants.BodyName);
+            }
+            return bodyParameter;
+        }
     }
 }