[http-server-csharp]: Fix routing issues with MFD requests (microsoft#5505)

Author: markcowl

.chronus/changes/mfd-01-2025-0-7-2-3-57.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/http-server-csharp"
+---
+
+[http-server-csharp]: Fix routing issues with MFD requests

packages/http-server-csharp/src/service.ts

@@ -661,7 +661,7 @@ export async function $onEmit(context: EmitContext<CSharpServiceEmitterOptions>)
       const multipart: boolean = this.#isMultipartRequest(httpOperation);
       const declParams = !multipart
         ? this.#emitHttpOperationParameters(httpOperation)
-        : this.#emitHttpOperationParameters(httpOperation, "HttpRequest request, Stream body");
+        : this.#emitHttpOperationParameters(httpOperation, true);
 
       if (multipart) {
         const context = this.emitter.getContext();
@@ -720,14 +720,14 @@ export async function $onEmit(context: EmitContext<CSharpServiceEmitterOptions>)
         ${this.emitter.emitOperationReturnType(operation)}
         public virtual async Task<IActionResult> ${operationName}(${declParams})
         {
-          var boundary = request.GetMultipartBoundary();
+          var boundary = Request.GetMultipartBoundary();
           if (boundary == null)
           {
              return BadRequest("Request missing multipart boundary");
           }
 
 
-          var reader = new MultipartReader(boundary, body);
+          var reader = new MultipartReader(boundary, Request.Body);
           ${
             hasResponseValue
               ? `var result = await ${this.emitter.getContext().resourceName}Impl.${operationName}Async(${this.#emitOperationCallParameters(httpOperation, "reader")});
@@ -912,7 +912,7 @@ export async function $onEmit(context: EmitContext<CSharpServiceEmitterOptions>)
 
     #emitHttpOperationParameters(
       operation: HttpOperation,
-      bodyParameter?: string,
+      bodyParameter?: boolean,
     ): EmitterOutput<string> {
       const signature = new StringBuilder();
       const bodyParam = operation.parameters.body;
@@ -930,10 +930,16 @@ export async function $onEmit(context: EmitContext<CSharpServiceEmitterOptions>)
       for (const parameter of requiredParams) {
         signature.push(
           code`${this.#emitOperationSignatureParameter(operation, parameter)}${
-            ++i < requiredParams.length || bodyParam !== undefined ? ", " : ""
+            ++i < requiredParams.length ? ", " : ""
           }`,
         );
       }
+      if (
+        requiredParams.length > 0 &&
+        (optionalParams.length > 0 || (bodyParameter === undefined && bodyParam !== undefined))
+      ) {
+        signature.push(code`, `);
+      }
       if (bodyParameter === undefined) {
         if (bodyParam !== undefined) {
           signature.push(
@@ -942,11 +948,9 @@ export async function $onEmit(context: EmitContext<CSharpServiceEmitterOptions>)
                 bodyParam.type,
                 Visibility.Create || Visibility.Update,
               ),
-            )} body${optionalParams.length > 0 ? ", " : ""}`,
+            )} body${requiredParams.length > 0 && optionalParams.length > 0 ? ", " : ""}`,
           );
         }
-      } else {
-        signature.push(code`${bodyParameter}${optionalParams.length > 0 ? ", " : ""}`);
       }
       i = 0;
       for (const parameter of optionalParams) {

packages/http-server-csharp/test/generation.test.ts

@@ -1123,17 +1123,19 @@ it("handles multipartBody requests and shared routes", async () => {
       }
 
       @sharedRoute
-      @route("/foo") 
+      @route("/foo/{id}") 
       @post 
       op fooBinary(
+        @path id: string,
         @header("content-type") contentType: "multipart/form-data", 
         @multipartBody body: FooRequest
       ): void;
 
       @sharedRoute
-      @route("/foo") 
+      @route("/foo/{id}") 
       @post 
       op fooJson(
+        @path id: string,
         @header("content-type") contentType: "application/json", 
         @body body: FooJsonRequest
       ): void;
@@ -1154,18 +1156,18 @@ it("handles multipartBody requests and shared routes", async () => {
           "using Microsoft.AspNetCore.WebUtilities;",
           "using Microsoft.AspNetCore.Http.Extensions;",
           `[Consumes("multipart/form-data")]`,
-          "public virtual async Task<IActionResult> FooBinary(HttpRequest request, Stream body)",
-          ".FooBinaryAsync(reader)",
-          "public virtual async Task<IActionResult> FooJson(FooJsonRequest body)",
-          ".FooJsonAsync(body)",
+          "public virtual async Task<IActionResult> FooBinary(string id)",
+          ".FooBinaryAsync(id, reader)",
+          "public virtual async Task<IActionResult> FooJson(string id, FooJsonRequest body)",
+          ".FooJsonAsync(id, body)",
         ],
       ],
       [
         "IContosoOperations.cs",
         [
           "using Microsoft.AspNetCore.WebUtilities;",
-          "Task FooBinaryAsync( MultipartReader reader);",
-          "Task FooJsonAsync( FooJsonRequest body);",
+          "Task FooBinaryAsync( string id, MultipartReader reader);",
+          "Task FooJsonAsync( string id, FooJsonRequest body);",
         ],
       ],
       [