Add default rules for setting operation ID

src/OpenApi/src/Services/OpenApiDocumentService.cs

@@ -12,6 +12,7 @@
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
@@ -140,6 +141,7 @@ private OpenApiOperation GetOperation(ApiDescription description, HashSet<OpenAp
         }
         var operation = new OpenApiOperation
         {
+            OperationId = GetOperationId(description),
             Summary = GetSummary(description),
             Description = GetDescription(description),
             Responses = GetResponses(description),
@@ -156,6 +158,10 @@ private OpenApiOperation GetOperation(ApiDescription description, HashSet<OpenAp
     private static string? GetDescription(ApiDescription description)
         => description.ActionDescriptor.EndpointMetadata.OfType<IEndpointDescriptionMetadata>().LastOrDefault()?.Description;
 
+    private static string? GetOperationId(ApiDescription description)
+        => description.ActionDescriptor.AttributeRouteInfo?.Name ??
+            description.ActionDescriptor.EndpointMetadata.OfType<IEndpointNameMetadata>().LastOrDefault()?.EndpointName;
+
     private static List<OpenApiTag>? GetTags(ApiDescription description)
     {
         var actionDescriptor = description.ActionDescriptor;

src/OpenApi/test/Services/OpenApiDocumentService/OpenApiDocumentServiceTests.Operations.cs

@@ -3,6 +3,8 @@
 
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Routing;
 using Microsoft.OpenApi.Models;
 
 public partial class OpenApiDocumentServiceTests
@@ -178,4 +180,58 @@ await VerifyOpenApiDocument(builder, document =>
             });
         });
     }
+
+    [Fact]
+    public async Task GetOpenApiOperation_CapturesEndpointNameAsOperationId()
+    {
+        // Arrange
+        var builder = CreateBuilder();
+
+        // Act
+        builder.MapGet("/api/todos", () => { }).WithName("GetTodos");
+
+        // Assert
+        await VerifyOpenApiDocument(builder, document =>
+        {
+            var operation = document.Paths["/api/todos"].Operations[OperationType.Get];
+            Assert.Equal("GetTodos", operation.OperationId);
+
+        });
+    }
+
+    [Fact]
+    public async Task GetOpenApiOperation_CapturesEndpointNameAttributeAsOperationId()
+    {
+        // Arrange
+        var builder = CreateBuilder();
+
+        // Act
+        builder.MapGet("/api/todos", [EndpointName("GetTodos")] () => { });
+
+        // Assert
+        await VerifyOpenApiDocument(builder, document =>
+        {
+            var operation = document.Paths["/api/todos"].Operations[OperationType.Get];
+            Assert.Equal("GetTodos", operation.OperationId);
+
+        });
+    }
+
+    [Fact]
+    public async Task GetOpenApiOperation_CapturesRouteAttributeAsOperationId()
+    {
+        // Act
+        var action = CreateActionDescriptor(nameof(ActionWithRouteAttributeName));
+
+        // Assert
+        await VerifyOpenApiDocument(action, document =>
+        {
+            var operation = document.Paths["/api/todos"].Operations[OperationType.Get];
+            Assert.Equal("GetTodos", operation.OperationId);
+
+        });
+    }
+
+    [Route("/api/todos", Name = "GetTodos")]
+    private void ActionWithRouteAttributeName() { }
 }

src/OpenApi/test/Services/OpenApiDocumentServiceTestsBase.cs

@@ -189,7 +189,9 @@ public ControllerActionDescriptor CreateActionDescriptor(string methodName = nul
 
         action.AttributeRouteInfo = new()
         {
-            Template = action.MethodInfo.GetCustomAttribute<RouteAttribute>()?.Template
+            Template = action.MethodInfo.GetCustomAttribute<RouteAttribute>()?.Template,
+            Name = action.MethodInfo.GetCustomAttribute<RouteAttribute>()?.Name,
+            Order = action.MethodInfo.GetCustomAttribute<RouteAttribute>()?.Order ?? 0,
         };
         action.RouteValues.Add("controller", "Test");
         action.RouteValues.Add("action", action.MethodInfo.Name);