Swagger "The method 'get' on path '../api/' is registered multiple times" error

Question

I use OpenAPI / Swagger in an Angular app based on .NET Core and I encounter "The method 'get' on path '../api/' is registered multiple times" error when generating frontend code as TypeScript using NSwag Studio. As far as I see on Github pages, etc. the problem is related to using the same route even if the method names in the API or Controller are not same as shown below:

[HttpGet]
public async Task<IEnumerable<DemoDto>> Get()
{
    return await Mediator.Send(new GetDemoQuery()); // GetDemoQuery()
}

[HttpGet("{id}")]
public async Task<DemoDto> GetById(int id)
{
    return await Mediator.Send(new GetGetDemoByIdQuery { Id = id }); // GetGetDemoByIdQuery()
}

So, is there any fix to solve the problem except? I already use different names as the method names, but encounter this problem.

Update: Here is my route definition in Startup.cs (I use .NET MVC before, and I think route definitions for .NET Core is set in Startup.cs as something like on ASP.NET Core - Routing. But in my app, the only route setting in Startuo.cs is the following:

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller}/{action=Index}/{id?}");
        endpoints.MapRazorPages();
});

Is there anything to apply extra? So, is there anything

Answer 1

I fixed the problem by adding [Route("Demo/Get/{id?}")] annotation. I hope the usage is correct and there is not a short or smarter way for this usage.

[HttpGet]
[Route("mycontroller")]
public async Task<IEnumerable<DemoDto>> Get()
{
    return await Mediator.Send(new GetDemoQuery()); // GetDemoQuery()
}

[HttpGet("{id}")]
[Route("mycontroller/{id?}")]
public async Task<DemoDto> GetById(int id)
{
    return await Mediator.Send(new GetGetDemoByIdQuery { Id = id }); // GetGetDemoByIdQuery()
}