services.AddControllersWithViews() vs services.AddMvc()

Question

In order to be able to add controllers in my ASP.NET Core app, I can add either

services.AddControllersWithViews()

or

services.AddMvc()

in ConfigureServices method at Startup class.

It looks like both of them are working fine for me. I would like to learn which one is better under which circumstances?

As far as I know, services.AddMvc() was the older way, but still available.

If I keep using services.AddMvc() would it be a problem in the future?

Answer 1

The source code speaks for itself

MvcServiceCollectionExtensions.AddMvc()

/// <summary>
/// Adds MVC services to the specified <see cref="IServiceCollection" />.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
/// <returns>An <see cref="IMvcBuilder"/> that can be used to further configure the MVC services.</returns>
public static IMvcBuilder AddMvc(this IServiceCollection services)
{
    if (services == null)
    {
        throw new ArgumentNullException(nameof(services));
    }

    services.AddControllersWithViews();
    return services.AddRazorPages();
}

/// <summary>
/// Adds MVC services to the specified <see cref="IServiceCollection" />.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
/// <param name="setupAction">An <see cref="Action{MvcOptions}"/> to configure the provided <see cref="MvcOptions"/>.</param>
/// <returns>An <see cref="IMvcBuilder"/> that can be used to further configure the MVC services.</returns>
public static IMvcBuilder AddMvc(this IServiceCollection services, Action<MvcOptions> setupAction)
{
    if (services == null)
    {
        throw new ArgumentNullException(nameof(services));
    }

    if (setupAction == null)
    {
        throw new ArgumentNullException(nameof(setupAction));
    }

    var builder = services.AddMvc();
    builder.Services.Configure(setupAction);

    return builder;
}

MvcServiceCollectionExtensions.AddControllersWithViews()

/// <summary>
/// Adds services for controllers to the specified <see cref="IServiceCollection"/>. This method will not
/// register services used for pages.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
/// <returns>An <see cref="IMvcBuilder"/> that can be used to further configure the MVC services.</returns>
/// <remarks>
/// <para>
/// This method configures the MVC services for the commonly used features with controllers with views. This
/// combines the effects of <see cref="MvcCoreServiceCollectionExtensions.AddMvcCore(IServiceCollection)"/>,
/// <see cref="MvcApiExplorerMvcCoreBuilderExtensions.AddApiExplorer(IMvcCoreBuilder)"/>,
/// <see cref="MvcCoreMvcCoreBuilderExtensions.AddAuthorization(IMvcCoreBuilder)"/>,
/// <see cref="MvcCorsMvcCoreBuilderExtensions.AddCors(IMvcCoreBuilder)"/>,
/// <see cref="MvcDataAnnotationsMvcCoreBuilderExtensions.AddDataAnnotations(IMvcCoreBuilder)"/>,
/// <see cref="MvcCoreMvcCoreBuilderExtensions.AddFormatterMappings(IMvcCoreBuilder)"/>,
/// <see cref="TagHelperServicesExtensions.AddCacheTagHelper(IMvcCoreBuilder)"/>,
/// <see cref="MvcViewFeaturesMvcCoreBuilderExtensions.AddViews(IMvcCoreBuilder)"/>,
/// and <see cref="MvcRazorMvcCoreBuilderExtensions.AddRazorViewEngine(IMvcCoreBuilder)"/>.
/// </para>
/// <para>
/// To add services for pages call <see cref="AddRazorPages(IServiceCollection)"/>.
/// </para>
/// </remarks>
public static IMvcBuilder AddControllersWithViews(this IServiceCollection services)
{
    if (services == null)
    {
        throw new ArgumentNullException(nameof(services));
    }

    var builder = AddControllersWithViewsCore(services);
    return new MvcBuilder(builder.Services, builder.PartManager);
}

/// <summary>
/// Adds services for controllers to the specified <see cref="IServiceCollection"/>. This method will not
/// register services used for pages.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param>
/// <param name="configure">An <see cref="Action{MvcOptions}"/> to configure the provided <see cref="MvcOptions"/>.</param>
/// <returns>An <see cref="IMvcBuilder"/> that can be used to further configure the MVC services.</returns>
/// <remarks>
/// <para>
/// This method configures the MVC services for the commonly used features with controllers with views. This
/// combines the effects of <see cref="MvcCoreServiceCollectionExtensions.AddMvcCore(IServiceCollection)"/>,
/// <see cref="MvcApiExplorerMvcCoreBuilderExtensions.AddApiExplorer(IMvcCoreBuilder)"/>,
/// <see cref="MvcCoreMvcCoreBuilderExtensions.AddAuthorization(IMvcCoreBuilder)"/>,
/// <see cref="MvcCorsMvcCoreBuilderExtensions.AddCors(IMvcCoreBuilder)"/>,
/// <see cref="MvcDataAnnotationsMvcCoreBuilderExtensions.AddDataAnnotations(IMvcCoreBuilder)"/>,
/// <see cref="MvcCoreMvcCoreBuilderExtensions.AddFormatterMappings(IMvcCoreBuilder)"/>,
/// <see cref="TagHelperServicesExtensions.AddCacheTagHelper(IMvcCoreBuilder)"/>,
/// <see cref="MvcViewFeaturesMvcCoreBuilderExtensions.AddViews(IMvcCoreBuilder)"/>,
/// and <see cref="MvcRazorMvcCoreBuilderExtensions.AddRazorViewEngine(IMvcCoreBuilder)"/>.
/// </para>
/// <para>
/// To add services for pages call <see cref="AddRazorPages(IServiceCollection)"/>.
/// </para>
/// </remarks>
public static IMvcBuilder AddControllersWithViews(this IServiceCollection services, Action<MvcOptions> configure)
{
    if (services == null)
    {
        throw new ArgumentNullException(nameof(services));
    }

    // This method excludes all of the view-related services by default.
    var builder = AddControllersWithViewsCore(services);
    if (configure != null)
    {
        builder.AddMvcOptions(configure);
    }

    return new MvcBuilder(builder.Services, builder.PartManager);
}

As you can see AddMvc is basically wrapping a call to AddControllersWithViews, with the addition of calling AddRazorPages.

If I keep using services.AddMvc() would it be a problem in the future?

There is really no way to answer that accurately.

Follow the advice provided by currently available documentation to avoid any unwanted behavior