Asp.net core default route

Question

Simplified Startup code:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseMvc(routes =>
    {
        routes.MapRoute(
        name: "default",
        template: "",
        defaults: new { controller = "Main", action = "Index" });
    });
}

After running application in Visual Studio 2015 I see in browser "localhost:xxx", but I don't see result of MainController.Index(). Just blank page. What did I miss?

Update:

Web.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <handlers>
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
    </handlers>
    <aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false"/>
  </system.webServer>
</configuration>

Update 2:

The problem comes from exception in dependency injected service to controller and because I forget to use developer exception page site just returned blank page to me. So I'm sorry for incorrect question, but routing is fine in my case.

Answer 1

routes.MapRoute(
    name: "default",
    template: "{controller}/{action}/{id?}",
    defaults: new { controller = "Main", action = "Index" });

routes.MapRoute(
    name: "default",
    template: "{controller=Main}/{action=Index}/{id?}");

These are the two ways of defining default route. You are mixing them. You need always to define a template. In the second way you can write the defaults directly in the template.

Answer 2

The easiest way for me (and without using MVC) was to set the controller to default route using empty [Route("")] custum attribute like so:

[ApiController]
[Route("")]
[Route("[controller]")]
public class MainController : ControllerBase
{ ... }

with Startup.Configure

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

Answer 3

For all of you who get blank page set PreserveCompilationContext to true:

  <PropertyGroup>
    <TargetFramework>netcoreapp1.1</TargetFramework>
    <PreserveCompilationContext>true</PreserveCompilationContext>
  </PropertyGroup>

in csproj in vs 2017 or

"buildOptions": {   "preserveCompilationContext": true }

in project.json

Answer 4

In Startup.cs class, use a convenient Method: UseMvcWithDefaultRoute():

public void Configure(IApplicationBuilder app, IHostingEnvironment 
{
   app.UseMvcWithDefaultRoute();
}

Can be used to change:

public void Configure(IApplicationBuilder app, IHostingEnvironment 
{
   app.UseMvc(routes =>
   {
      routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}");
   });
}

More info in Microsoft documentation

Answer 5

Another solution would be to redirect "/" to another url

 app.UseEndpoints(endpoints =>
        {
            endpoints.MapDefaultControllerRoute();

            endpoints.MapGet("/", context =>
            {
                return Task.Run(() => context.Response.Redirect("/Account/Login"));
            });
        });