public class FaRequestCultureProvider : RequestCultureProvider
    {
        public override Task<ProviderCultureResult> DetermineProviderCultureResult(HttpContext httpContext)
        {
            return Task.FromResult(new ProviderCultureResult("fa-IR"));
        }
    }

        public void Configure(IApplicationBuilder app)
        {
            var requestLocalizationOptions = new RequestLocalizationOptions
            {
                DefaultRequestCulture = new RequestCulture(new CultureInfo("fa-IR")),
                SupportedCultures = new[]
                {
                    new CultureInfo("en-US"),
                    new CultureInfo("fa-IR")
                },
                SupportedUICultures = new[]
                {
                    new CultureInfo("en-US"),
                    new CultureInfo("fa-IR")
                }
            };
            requestLocalizationOptions.RequestCultureProviders.Insert(0, new FaRequestCultureProvider());
            app.UseRequestLocalization(requestLocalizationOptions);

    public class FaLanguageActionFilterAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            CultureInfo.CurrentCulture = new CultureInfo("fa-IR");
            CultureInfo.CurrentUICulture = new CultureInfo("fa-IR");
            base.OnActionExecuting(context);
        }
    }

    public abstract class MyCustomBaseView<TModel> : RazorPage<TModel>
    {
        protected MyCustomBaseView()
        {
            CultureInfo.CurrentCulture = new CultureInfo("fa-IR");
            CultureInfo.CurrentUICulture = new CultureInfo("fa-IR");
        }

@{
    Layout = "_Layout";
}

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc.Localization;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Razor.Internal;

namespace Core1RtmTestResources.StartupCustomizations
{
    public abstract class MyCustomBaseView<TModel> : RazorPage<TModel>
    {
        //روش خاص تزریق وابستگی‌ها در فایل ویژه‌ی جاری
        [RazorInject]
        public IHtmlLocalizerFactory MyHtmlLocalizerFactory { get; set; }

        public IHtmlLocalizer MySharedLocalizer => MyHtmlLocalizerFactory.Create(
            baseName: "SharedResource" /*مشخصات*/,
            location: "Core1RtmTestResources.ExternalResources" /*نام اسمبلی ثالث*/);

        public bool IsAuthenticated()
        {
            return Context.User.Identity.IsAuthenticated;
        }

#pragma warning disable 1998
        public override async Task ExecuteAsync()
        {
        }
#pragma warning restore 1998
    }
}

{
    "dependencies": {
        //same as before
        "Microsoft.AspNetCore.Mvc.Razor": "1.0.0"
    }
}

@using Core1RtmTestResources
@using Microsoft.AspNetCore.Mvc.Localization
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

@inherits Core1RtmTestResources.StartupCustomizations.MyCustomBaseView<TModel>

public void ConfigureServices(IServiceCollection services)
{
  services.AddLocalization(options =>
  {
   options.ResourcesPath = "Resources";
  });
 
  services.AddMvc()
    .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix)
    .AddDataAnnotationsLocalization(options=>
    {
      options.DataAnnotationLocalizerProvider = (type, factory) =>
      {
       return factory.Create(
        baseName: type.FullName /* بر این اساس نام فایل منبع متناظر باید به همراه ذکر فضای نام پایه آن هم باشد */,
        location: "Core1RtmTestResources.ExternalResources" /*نام اسمبلی ثالث*/);
      };
    });

public TestLocalController(
            IStringLocalizer<TestLocalController> stringLocalizer,
            IHtmlLocalizer<TestLocalController> htmlLocalizer)

private readonly IStringLocalizer _stringLocalizer;
private readonly IHtmlLocalizer _htmlLocalizer;
 
public TestLocalController(
    IStringLocalizerFactory stringLocalizerFactory,
    IHtmlLocalizerFactory htmlLocalizerFactory)
{
    _stringLocalizer = stringLocalizerFactory.Create(
        baseName: "Controllers.TestLocalController" /*مشخصات کنترلر جاری*/,
        location: "Core1RtmTestResources.ExternalResources" /*نام اسمبلی ثالث*/);
    _htmlLocalizer = htmlLocalizerFactory.Create(
        baseName: "Controllers.TestLocalController" /*مشخصات کنترلر جاری*/,
        location: "Core1RtmTestResources.ExternalResources" /*نام اسمبلی ثالث*/);
}