This localhost page can’t be found, possible configuration problem

Question

Whatever page I try to load after running my api, I get the "This localhost page can't be found" 404 error, even if I try to run a method that only has an "Ok" return. I'm thinking the issue might lie in the way I configured my app. That, or I made some errors while routing.

I've tried messing around with app configuration, looking at examples, but most of them have additional NuGet packages installed. I tried using the .AddControllers() method in the ConfigureServices method, which resulted in a syntax error, I tried using .UseRouting() in my Configure function, and again, I was met with a syntax error.

Startup class:

public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IRepositoryWrapper, RepositoryWrapper>();
            services.AddDbContext<ArtGalleriesContext>(
                options=>options.UseSqlServer(
                    Configuration.GetConnectionString("Database")));
            //services.AddScoped<IArtItemRepository1, ArtItemRepository1>();
            services.AddMvc();
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });

Program class:

public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();

I am trying to call this function

 [Route("api/[controller]")]
    [ApiController]
    public class AdminController : ControllerBase
 [HttpGet("/user/add/{num1}/")]
        public IActionResult SumActionResult(int num1)
        {
            return Ok(num1 );
        }

like this: api/admin/users/add/1 and have it display 1 in my web page to confirm functionality. I am getting the "This localhost page can't be found" error instead.

Answer 1

You need something like this

 [HttpGet("user/add/{num1}")]
 public IActionResult SumActionResult(int num1)
 {
     return Ok(num1 );
 }

Also note that in route your have user not 'users'. For further details you can read https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-2.2

Answer 2

Your problem is here.

[HttpGet("/user/add/{num1}/")]

Because of the preceding slash ( / ), the route is just /user/add/{num1} , not /api/admin/user/add/{num1} . Remove the preceding slash:

[HttpGet("user/add/{num1}/")]