.Net: Handle missing operation id in OpenApi spec

dotnet/src/Functions/Functions.OpenApi/OpenApiKernelPluginFactory.cs

@@ -7,6 +7,7 @@
 using System.IO;
 using System.Linq;
 using System.Net.Http;
+using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
@@ -274,7 +275,7 @@ async Task<RestApiOperationResponse> ExecuteAsync(Kernel kernel, KernelFunction
             method: ExecuteAsync,
             new KernelFunctionFromMethodOptions
             {
-                FunctionName = ConvertOperationIdToValidFunctionName(operation.Id, logger),
+                FunctionName = ConvertOperationToValidFunctionName(operation, logger),
                 Description = operation.Description,
                 Parameters = parameters,
                 ReturnParameter = returnParameter,
@@ -291,6 +292,37 @@ async Task<RestApiOperationResponse> ExecuteAsync(Kernel kernel, KernelFunction
     /// <summary>The metadata property bag key to use for the list of extension values provided in the swagger file at the operation level.</summary>
     private const string OperationExtensionsMetadataKey = "operation-extensions";
 
+    /// <summary>
+    /// Converts operation id to valid <see cref="KernelFunction"/> name.
+    /// A function name can contain only ASCII letters, digits, and underscores.
+    /// </summary>
+    /// <param name="operation">The REST API operation.</param>
+    /// <param name="logger">The logger.</param>
+    /// <returns>Valid KernelFunction name.</returns>
+    private static string ConvertOperationToValidFunctionName(RestApiOperation operation, ILogger logger)
+    {
+        if (!string.IsNullOrWhiteSpace(operation.Id))
+        {
+            return ConvertOperationIdToValidFunctionName(operationId: operation.Id, logger: logger);
+        }
+
+        // Tokenize operation path on forward and back slashes
+        string[] tokens = operation.Path.Split('/', '\\');
+        StringBuilder result = new();
+        result.Append(CultureInfo.CurrentCulture.TextInfo.ToTitleCase(operation.Method.ToString()));
+
+        foreach (string token in tokens)
+        {
+            // Removes all characters that are not ASCII letters, digits, and underscores.
+            string formattedToken = RemoveInvalidCharsRegex().Replace(token, "");
+            result.Append(CultureInfo.CurrentCulture.TextInfo.ToTitleCase(formattedToken.ToLower(CultureInfo.CurrentCulture)));
+        }
+
+        logger.LogInformation("""Operation method "{0}" with path "{1}" converted to "{2}" to comply with SK Function name requirements. Use "{2}" when invoking function.""", operation.Method, operation.Path, result, result);
+
+        return result.ToString();
+    }
+
     /// <summary>
     /// Converts operation id to valid <see cref="KernelFunction"/> name.
     /// A function name can contain only ASCII letters, digits, and underscores.
@@ -336,7 +368,7 @@ private static string ConvertOperationIdToValidFunctionName(string operationId,
     private static partial Regex RemoveInvalidCharsRegex();
 #else
     private static Regex RemoveInvalidCharsRegex() => s_removeInvalidCharsRegex;
-    private static readonly Regex s_removeInvalidCharsRegex = new("[^0-9A-Za-z_]", RegexOptions.Compiled);
+    private static readonly Regex s_removeInvalidCharsRegex = new("[^0-9A-Za-z_./-/{/}]", RegexOptions.Compiled);
 #endif
 
     #endregion

dotnet/src/Functions/Functions.UnitTests/OpenApi/OpenApiKernelPluginFactoryTests.cs

@@ -297,6 +297,44 @@ public async Task ItShouldReplicateMetadataToOperationAsync(string documentFileN
         Assert.Contains("x-object-extension", nonNullOperationExtensions.Keys);
     }
 
+    [Fact]
+    public async Task ItShouldHandleEmptyOperationNameAsync()
+    {
+        // Arrange
+        var openApiDocument = ResourcePluginsProvider.LoadFromResource("documentV3_0.json");
+
+        using var content = OpenApiTestHelper.ModifyOpenApiDocument(openApiDocument, (doc) =>
+        {
+            doc["paths"]!["/secrets/{secret-name}"]!["get"]!["operationId"] = "";
+        });
+
+        // Act
+        var plugin = await OpenApiKernelPluginFactory.CreateFromOpenApiAsync("fakePlugin", content, this._executionParameters);
+
+        // Assert
+        Assert.Equal(5, plugin.Count());
+        Assert.True(plugin.TryGetFunction("GetSecretsSecretname", out var _));
+    }
+
+    [Fact]
+    public async Task ItShouldHandleNullOperationNameAsync()
+    {
+        // Arrange
+        var openApiDocument = ResourcePluginsProvider.LoadFromResource("documentV3_0.json");
+
+        using var content = OpenApiTestHelper.ModifyOpenApiDocument(openApiDocument, (doc) =>
+        {
+            doc["paths"]!["/secrets/{secret-name}"]!["get"]!.AsObject().Remove("operationId");
+        });
+
+        // Act
+        var plugin = await OpenApiKernelPluginFactory.CreateFromOpenApiAsync("fakePlugin", content, this._executionParameters);
+
+        // Assert
+        Assert.Equal(5, plugin.Count());
+        Assert.True(plugin.TryGetFunction("GetSecretsSecretname", out var _));
+    }
+
     [Fact]
     public void Dispose()
     {