Error: AmbiguousMatchException when loading multi-table swashbuckle definition

[adrianhall]

Describe the bug

When loading /swagger or /swagger/v1/swagger.json set up with Swashbuckle, I receive the following error:

Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Conflicting method/path combination "DELETE {id}" for actions - Sample.TodoApi.Controllers.ItemsController.DeleteAsync (Sample.TodoApi),Sample.TodoApi.Controllers.ListsController.DeleteAsync (Sample.TodoApi). Actions require a unique method/path combination for Swagger/OpenAPI 3.0. Use ConflictingActionsResolver as a workaround
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.PrepareGenerateOperation(IGrouping`2 group)
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperationsAsync(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePathsAsync(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository, Func`3 operationsGenerator)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePathsAsync(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerAsync(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

Microsoft.AspNetCore.Routing.Matching.AmbiguousMatchException: The request matched multiple endpoints. Matches: 

Sample.TodoApi.Controllers.ItemsController.ReadAsync (Sample.TodoApi)
Sample.TodoApi.Controllers.ListsController.ReadAsync (Sample.TodoApi)
   at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ReportAmbiguity(Span`1 candidateState)
   at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.ProcessFinalCandidates(HttpContext httpContext, Span`1 candidateState)
   at Microsoft.AspNetCore.Routing.Matching.DefaultEndpointSelector.Select(HttpContext httpContext, Span`1 candidateState)
   at Microsoft.AspNetCore.Routing.Matching.DfaMatcher.MatchAsync(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

To Reproduce

• Create an AppDbContext with two datasets.
• Create two controllers, each of which have an attribute [Route("tables/[controller]")] on them. See https://communitytoolkit.github.io/Datasync/in-depth/server/index.html#create-a-table-controller
• Program.cs looks like this:

using CommunityToolkit.Datasync.Server;
using CommunityToolkit.Datasync.Server.Swashbuckle;
using Microsoft.EntityFrameworkCore;
using Sample.TodoApi.Database;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddDbContext<AppDbContext>(options =>
{
    options.UseSqlServer(builder.Configuration.GetConnectionString("Database"), sqlOptions =>
    {
        sqlOptions.EnableRetryOnFailure();
    });

    if (builder.Environment.IsDevelopment())
    {
        options.EnableDetailedErrors();
        options.EnableSensitiveDataLogging();
        options.EnableThreadSafetyChecks();
    }
});

builder.Services.AddHttpContextAccessor();
builder.Services.AddDatasyncServices();
builder.Services.AddControllers();

builder.Services
    .AddEndpointsApiExplorer()
    .AddSwaggerGen(options => options.AddDatasyncControllers())
    .AddSwaggerGenNewtonsoftSupport();

var app = builder.Build();

await using (var scope = app.Services.CreateAsyncScope())
{
    var context = scope.ServiceProvider.GetRequiredService<AppDbContext>();
    await context.InitializeAsync(app.Environment);
}

app.UseHttpsRedirection();

app.UseSwagger();
app.UseSwaggerUI(options =>
{
    options.SwaggerEndpoint("/swagger/v1/swagger.json", "v1");
    options.RoutePrefix = string.Empty;
});

app.UseAuthorization();
app.MapControllers();
app.Run();

Expected behavior

No error - OpenAPI.yaml / swagger.json is created.

What platforms?

• Server:
  • Version of dotnet being used to compile? dotnet 8.0.420
  • Library versions? 8.0.2, EF Core 8.0.8, ASP.NET Core 8.0.8
  • What database are you using? SQL LocalDB
  • Where are you running the server? Localhost