Thread.CurrentThread.CurrentUICulture = new CultureInfo("fa-IR");
Thread.CurrentThread.CurrentUICulture = CultureInfo.CreateSpecificCulture("fa-IR");

[Required(ErrorMessageResourceName = "ResourceKeyName", ErrorMessageResourceType = typeof(<SolutionName>.Resources.<ResourceClassName>))]

public class LocalizationDisplayNameAttribute : DisplayNameAttribute
  {
    private readonly DisplayAttribute _display;
    public LocalizationDisplayNameAttribute(string resourceName, Type resourceType)
    {
      _display = new DisplayAttribute { ResourceType = resourceType, Name = resourceName };
    }
    public override string DisplayName
    {
      get
      {
        try
        {
          return _display.GetName();
        }
        catch (Exception)
        {
          return _display.Name;
        }
      }
    }
  }

public class LocalizationDisplayNameAttribute : DisplayNameAttribute
{
    private readonly PropertyInfo nameProperty;
    public LocalizationDisplayNameAttribute(string displayNameKey, Type resourceType = null)
        : base(displayNameKey)
    {
        if (resourceType != null)
            nameProperty = resourceType.GetProperty(base.DisplayName, BindingFlags.Static | BindingFlags.Public);
    }
    public override string DisplayName
    {
        get
        {
            if (nameProperty == null) base.DisplayName;
            return (string)nameProperty.GetValue(nameProperty.DeclaringType, null);
        }
    }
}

[LocalizationDisplayName("ResourceKeyName", typeof(<SolutionName>.Resources.<ResourceClassName>))]

public class BaseController : Controller
  {
    private const string LanguageCookieName = "MyLanguageCookieName";
    protected override void ExecuteCore()
    {
      var cookie = HttpContext.Request.Cookies[LanguageCookieName];
      string lang;
      if (cookie != null)
      {
        lang = cookie.Value;
      }
      else
      {
        lang = ConfigurationManager.AppSettings["DefaultCulture"] ?? "fa-IR";
        var httpCookie = new HttpCookie(LanguageCookieName, lang) { Expires = DateTime.Now.AddYears(1) };
        HttpContext.Response.SetCookie(httpCookie);
      }
      Thread.CurrentThread.CurrentUICulture = CultureInfo.CreateSpecificCulture(lang);
      base.ExecuteCore();
    }
  }

public class LocalizationActionFilterAttribute : ActionFilterAttribute
  {
    private const string LanguageCookieName = "MyLanguageCookieName";
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
      var cookie = filterContext.HttpContext.Request.Cookies[LanguageCookieName];
      string lang;
      if (cookie != null)
      {
        lang = cookie.Value;
      }
      else
      {
        lang = ConfigurationManager.AppSettings["DefaultCulture"] ?? "fa-IR";
        var httpCookie = new HttpCookie(LanguageCookieName, lang) { Expires = DateTime.Now.AddYears(1) };
        filterContext.HttpContext.Response.SetCookie(httpCookie);
      }
      Thread.CurrentThread.CurrentUICulture = CultureInfo.CreateSpecificCulture(lang);
      base.OnActionExecuting(filterContext);
    }
  }

<select id="langs" onchange="languageChanged()">
  <option value="fa-IR">فارسی</option>
  <option value="en-US">انگلیسی</option>
</select>
<script type="text/javascript">
  function languageChanged() {
    setCookie("MyLanguageCookieName", $('#langs').val(), 365);
    window.location.reload();
  }
  document.ready = function () {
    $('#langs').val(getCookie("MyLanguageCookieName"));
  };
  function setCookie(name, value, exdays, path) {
    var exdate = new Date();
    exdate.setDate(exdate.getDate() + exdays);
    var newValue = escape(value) + ((exdays == null) ? "" : "; expires=" + exdate.toUTCString()) + ((path == null) ? "" : "; path=" + path) ;
    document.cookie = name + "=" + newValue;
  }
  function getCookie(name) {
    var i, x, y, cookies = document.cookie.split(";");
    for (i = 0; i < cookies.length; i++) {
      x = cookies[i].substr(0, cookies[i].indexOf("="));
      y = cookies[i].substr(cookies[i].indexOf("=") + 1);
      x = x.replace(/^\s+|\s+$/g, "");
      if (x == name) {
        return unescape(y);
      }
    }
  }
</script> 

GET https://www.dntips.ir HTTP/1.1
...
Accept-Language: fa-IR,en-US;q=0.5
...

Accept-Language: fa-IR,fa;q=0.8,en-US;q=0.5,ar-BH;q=0.3

<system.web>
    <globalization enableClientBasedCulture="true" uiCulture="auto" culture="auto"></globalization>
</system.web>

var langs = filterContext.HttpContext.Request.UserLanguages;

routes.MapRoute(
    "Localization", // Route name
    "{lang}/{controller}/{action}/{id}", // URL with parameters
    new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
);

public class BaseController : Controller
{
  protected override void ExecuteCore()
  {
    var lang = RouteData.Values["lang"];
    if (lang != null && !string.IsNullOrWhiteSpace(lang.ToString()))
    {
      Thread.CurrentThread.CurrentUICulture = CultureInfo.CreateSpecificCulture(lang.ToString());
    }
    base.ExecuteCore();
  }
}

public class BaseController : Controller
{
  protected override void OnActionExecuted(ActionExecutedContext context)
  {
    var view = context.Result as ViewResultBase;
    if (view == null) return; // not a view
    var viewName = view.ViewName;
    view.ViewName = GetGlobalizationViewName(viewName, context);
    base.OnActionExecuted(context);
  }
  private static string GetGlobalizationViewName(string viewName, ControllerContext context)
  {
    var cultureName = Thread.CurrentThread.CurrentUICulture.Name;
    if (cultureName == "en-US") return viewName; // default culture
    if (string.IsNullOrEmpty(viewName))
      return context.RouteData.Values["action"] + "." + cultureName; // "Index.fa"
    int i;
    if ((i = viewName.IndexOf('.')) > 0) // ex: Index.cshtml
      return viewName.Substring(0, i + 1) + cultureName + viewName.Substring(i); // "Index.fa.cshtml"
    return viewName + "." + cultureName; // "Index" ==> "Index.fa"
  }
}

public sealed class RazorGlobalizationViewEngine : RazorViewEngine
  {
    protected override IView CreatePartialView(ControllerContext controllerContext, string partialPath)
    {
      return base.CreatePartialView(controllerContext, GetGlobalizationViewPath(controllerContext, partialPath));
    }
    protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)
    {
      return base.CreateView(controllerContext, GetGlobalizationViewPath(controllerContext, viewPath), masterPath);
    }
    private static string GetGlobalizationViewPath(ControllerContext controllerContext, string viewPath)
    {
      //var controllerName = controllerContext.RouteData.GetRequiredString("controller");
      var request = controllerContext.HttpContext.Request;
      var lang = request.Cookies["MyLanguageCookie"];
      if (lang != null && !string.IsNullOrEmpty(lang.Value) && lang.Value != "en-US")
      {
        var localizedViewPath = Regex.Replace(viewPath, "^~/Views/", string.Format("~/Views/Globalization/{0}/", lang.Value));
        if (File.Exists(request.MapPath(localizedViewPath))) viewPath = localizedViewPath;
      }
      return viewPath;
    }

protected void Application_Start()
{
  ViewEngines.Engines.Clear();
  ViewEngines.Engines.Add(new RazorGlobalizationViewEngine());
}

var result = 
    from product in dbContext.Products
    where product.Category.Name == "Toys"
    where product.Price >= 2.50
    select product.Name;

var result = dbContext.Products
    .Where(p => p.Category.Name == "Toys" && p.Price >= 250)
    .Select(p => p.Name);

در پرس و چو‌های بالا فیلد‌های مورد نیاز در قسمت Select در زمان Compile شناخته شده هستند . اما گاهی ممکن است فیلد‌های مورد نیاز در زمان اجرا مشخص شوند.

به عنوان مثال یک گزارش ساز پویا که کاربر مشخص می‌کند چه ستون هایی در خروجی نمایش داده شوند یا یک جستجوی پیشرفته که ستون‌های خروجی به اختیار کاربر در زمان اجرا مشخص می‌شوند. 

این مدل را در نظر داشته باشید :

    public class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Field1 { get; set; }
        public string Field2 { get; set; }
        public string Field3 { get; set; }


        public static IEnumerable<Student> GetStudentSource()
        {
            for (int i = 0; i < 10; i++)
            {
                yield return new Student
                                 {
                                     Id = i,
                                     Name = "Name " + i,
                                     Field1 = "Field1 " + i,
                                     Field2 = "Field2 " + i,
                                     Field3 = "Field3 " + i
                                 };
            }
        }
    }

ستون‌های کلاس Student  را در رابط کاربری برنامه جهت انتخاب به کاربر نمایش می‌دهیم. سپس کاربر یک یا چند ستون را انتخاب می‌کند که قسمت Select  کوئری برنامه باید  بر اساس فیلد‌های مورد نظر کاربر مشخص شود.

یکی از روش هایی که می‌توان از آن بهره برد استفاده از کتاب خانه Dynamic LINQ معرفی شده در اینجا می باشد.

این کتابخانه جهت سهولت در نصب به کمک NuGet در این آدرس قرار دارد.

فرض بر این است که فیلد‌های انتخاب شده توسط کاربر با "," از یکدیگر جدا شده اند. 

    public class Program
    {
        private static void Main(string[] args)
        {
            System.Console.WriteLine("Specify the desired fields : ");
            string fields = System.Console.ReadLine();
            IEnumerable<Student> students = Student.GetStudentSource();
            IQueryable output = students.AsQueryable().Select(string.Format("new({0})", fields));
            foreach (object item in output)
            {
                System.Console.WriteLine(item);
            }
          
            System.Console.ReadKey();
        }
  
    }

همانطور که در عکس ذیل مشاهده می‌کنید پس از اجرای برنامه ، فیلد‌های انتخاب شده توسط کاربر از منبع داده‌ی دریافت شده و در خروجی نمایش داده شده اند.

این روش مزایا و معایب خودش را دارد ، به عنوان مثال خروجی یک لیست از شیء Student  نیست یا این Select  فقط برای روی یک شیء IQueryable  قابل انجام است.

روش دیگری که می‌توان از آن بهره جست استفاده از یک متد کمکی جهت تولید پویای عبارت Lambda  ورودی Select  می باشد :  

    public  class SelectBuilder <T>
    {
        public static Func<T, T> CreateNewStatement(string fields)
        {
            // input parameter "o"
            var xParameter = Expression.Parameter(typeof(T), "o");


            // new statement "new T()"
            var xNew = Expression.New(typeof(T));

            // create initializers
            var bindings = fields.Split(',').Select(o => o.Trim())
                .Select(o =>
                {

                    // property "Field1"
                    var property = typeof(T).GetProperty(o);

                    // original value "o.Field1"
                    var xOriginal = Expression.Property(xParameter, property);

                    // set value "Field1 = o.Field1"
                    return Expression.Bind(property, xOriginal);
                }
            ).ToList();

            // initialization "new T { Field1 = o.Field1, Field2 = o.Field2 }"
            var xInit = Expression.MemberInit(xNew, bindings);

            // expression "o => new T { Field1 = o.Field1, Field2 = o.Field2 }"
            var lambda = Expression.Lambda<Func<T, T>>(xInit, xParameter);

            // compile to Func<T, T>
            return lambda.Compile();
        }
    }

o=>new Student()

var property = typeof(T).GetProperty(o);

POST /accounts/ClientLogin HTTP/1.1
User-Agent: curl/7.15.1 (i486-pc-linux-gnu) libcurl/7.15.1
OpenSSL/0.9.8a zlib/1.2.3 libidn/0.5.18
Host: www.google.com
Accept: */*
Content-Length: 103
Content-Type: application/x-www-form-urlencoded
accountType=GOOGLE&Email=userName@google.com&Passwd=myPasswrd&source=curl-tester-1.0&service=analytics

HTTP/1.1 200 OK
Content-Type: text/plain
Cache-control: no-cache
Pragma: no-cache
Date: Mon, 02 Jun 2008 22:08:51 GMT
Content-Length: 497
SID=DQ...
LSID=DQAA...
Auth=DQAAAG8...

        string getSecurityToken()
       {
           if (string.IsNullOrEmpty(Email))
               throw new NullReferenceException("Email is required!");

           if (string.IsNullOrEmpty(Password))
               throw new NullReferenceException("Password is required!");

           WebRequest request = WebRequest.Create("https://www.google.com/accounts/ClientLogin");
           request.Method = "POST";

           string postData = "accountType=GOOGLE&Email=" + Email + "&Passwd=" + Password + "&service=analytics&source=vahid-testapp-1.0";
           byte[] byteArray = Encoding.ASCII.GetBytes(postData);

           request.ContentType = "application/x-www-form-urlencoded";
           request.ContentLength = byteArray.Length;

           using (Stream dataSt = request.GetRequestStream())
           {
               dataSt.Write(byteArray, 0, byteArray.Length);
           }

           string auth = string.Empty;
           using (WebResponse response = request.GetResponse())
           {
               using (Stream dataStream = response.GetResponseStream())
               {
                   using (StreamReader reader = new StreamReader(dataStream))
                   {
                       string responseFromServer = reader.ReadToEnd().Trim();
                       string[] tokens = responseFromServer.Split('\n');
                       foreach (string token in tokens)
                       {
                           if (token.StartsWith("SID="))
                               continue;

                           if (token.StartsWith("LSID="))
                               continue;

                           if (token.StartsWith("Auth="))
                           {
                               auth = token.Substring(5);
                           }
                           else
                           {
                               throw new AuthenticationException("Error authenticating Google user " + Email);
                           }
                       }
                   }
               }
           }

           return auth;

       }

       string getAvailableProfiles(string authToken)
       {
           return fetchPage("https://www.google.com/analytics/feeds/accounts/default", authToken);
       }

            string url = string.Format("https://www.google.com/analytics/feeds/data?ids={0}&metrics=ga:pageviews&start-date={1}&end-date={2}", id, from, to);
           return fetchPage(url, auth);

            CGoogleAnalytics cga = new CGoogleAnalytics
                                      {
                                          Email = "username@gmail.com",
                                          Password = "password",
                                          From = DateTime.Now.Subtract(TimeSpan.FromDays(1)),
                                          To = DateTime.Now.Subtract(TimeSpan.FromDays(1))
                                      };
           List<CGoogleAnalytics.SitePagePreviews> pagePreviews =
               cga.GetTotalNumberOfPageViews();

           foreach (var list in pagePreviews)
           {
               //string site = list.Site;
               //int pw = list.PagePreviews;
           }

var list = new List<int> {1,1,2,2,3,3,3,4,4,4};

var hash = new HashSet<int>();
var duplicates = list.Where(i => !hash.Add(i));

var movies = new List<Movie>
{
    new Movie("Titanic", 1998, 4.5f),
    new Movie("The Fifth Element", 1997, 4.6f),
    new Movie("Terminator 2", 1991, 4.7f),
    new Movie("Avatar", 2009, 5),
    new Movie("Platoon", 1986, 4),
    new Movie("My Neighbor Totoro", 1988, 5)
};

var distinctRatings = movies.DistinctBy(movie => movie.Rating);

// Output:
// Titanic,The Fifth Element,Terminator 2,Avatar,Platoon

namespace MvcApplication3.Models
{
    public class Product
    {
        public Product(string productNumber, string name, decimal price)
        {
            Name = name;
            Price = price;
            ProductNumber = productNumber;
        }
        public string ProductNumber { get; set; }
        public string Name { get; set; }
        public decimal Price { get; set; }
    }
}

using System.Collections.Generic;

namespace MvcApplication3.Models
{
    public class Products : List<Product>
    {
        public Products()
        {
            this.Add(new Product("D123", "Super Fast Bike", 1000M));
            this.Add(new Product("A356", "Durable Helmet", 123.45M));
            this.Add(new Product("M924", "Soft Bike Seat", 34.99M));
        }
    }
}

using System.Web.Mvc;
using MvcApplication3.Models;

namespace MvcApplication3.Controllers
{
    public class ProductsController : Controller
    {
        public ActionResult Index()
        {
            var products = new Products();
            return View(products);
        }
    }
}

@model List<MvcApplication3.Models.Product>
@{
    ViewBag.Title = "Index";
    var number = 12;
    var data = "some text...";    
    <h2>line1: @data</h2>
    
    @:line-2: @data <‪br />
    <text>line-3:</text> @data
}
<‪br />
site@(data)
<‪br />
@@name
<‪br />
@(number/10)
<‪br />
First product: @Model.First().Name
<‪br />
@if (@number>10)
{
  <span>@data</span>
}
else
{
  <text>Plain Text</text>
}
<‪br />
@foreach (var item in Model)
{
    <li>@item.Name, $@item.Price </li>
}

@*
    A Razor Comment
*@

<‪br />
@("First product: " + Model.First().Name)
<‪br />
<img src="@(number).jpg" />

@model List<MvcApplication3.Models.Product>
@{
    ViewBag.Title = "Index";
    var number = 12;
    var data = "some text...";    
    <h2>line1: @data</h2>
    
    @:line-2: @data <‪br />
    <text>line-3:</text> @data
}

@{  ...Code Block.... }

<‪br />
site@data

<‪br />
site@(data)

<img src="@(number).jpg" />

<‪br />
@name

<‪br />
@@name

First product: @Model.First().Name

<‪br />
@number/10

<‪br />
@(number/10)

@if (@number>10)
{
  <span>@data</span>
}
else
{
  <text>Plain Text</text>
}

@if( i < 1 ) int myVar=0;

@foreach (var item in Model)
{
    <li>@item.Name, $@item.Price </li>
}

@using namespace;

@*
    A Razor Comment / Server side Comment
*@

@("First product: " + Model.First().Name)