Swagger is not generating api documentation correctly

Question

I have an asp.net core web api project and I am using version 3.1. I installed the swagger package and configured it, everything is normal, but the API of the swagger page is not seen, why is this, this is the configuration information of my reference document.

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<TodoContext>(opt =>
        opt.UseInMemoryDatabase("TodoList"));
    services.AddControllers();

    // Register the Swagger generator, defining 1 or more Swagger documents
    services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new OpenApiInfo
        {
            Version = "v1",
            Title = "ToDo API",
            Description = "A simple example ASP.NET Core Web API",
            TermsOfService = new Uri("https://example.com/terms"),
            Contact = new OpenApiContact
            {
                Name = "Shayne Boyer",
                Email = string.Empty,
                Url = new Uri("https://twitter.com/spboyer"),
            },
            License = new OpenApiLicense
            {
                Name = "Use under LICX",
                Url = new Uri("https://example.com/license"),
            }
        });

        // Set the comments path for the Swagger JSON and UI.
        var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
        var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
        c.IncludeXmlComments(xmlPath);
    });
}

public void Configure(IApplicationBuilder app)
{
    // Enable middleware to serve generated Swagger as a JSON endpoint.
    app.UseSwagger(c =>
    {
        c.SerializeAsV2 = true;
    });

    // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
    // specifying the Swagger JSON endpoint.
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
    });

    app.UseRouting();
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

Answer 1

I reproduced the problem according to your code. I created a Controller myself, but since the routing address was not added, the first time I opened it was like this:

There is only one default route, but in my project I have added a HomeController which also doesn't show up in that API.

 public class HomeController : Controller
    {

        [HttpGet]
     
        public string Index()
        {
            return "test";
        }
    }

This is because I did not add the routing address and it did not display.

[Route("api/[controller]")]
public class HomeController : Controller
{

    [HttpGet]
    [Route("test")]
    public string Index()
    {
        return "test";
    }
}

After adding：

I don't know if you are for this reason, if not, can you explain your steps in detail? Or provide an interface where your swagger does not display the API.

Reference documentation:

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