public void ConfigureServices(IServiceCollection services)
{ 
    services.AddFeatureManagement().AddFeatureFilter<TimeWindowFilter>();
}

[FilterAlias("BrowserFilter")]
public class BrowserFilter:IFeatureFilter
    {
        private readonly IHttpContextAccessor _httpContextAccessor;

        public BrowserFilter(IHttpContextAccessor httpContextAccessor)
        {
            _httpContextAccessor = httpContextAccessor ?? throw new ArgumentNullException(nameof(httpContextAccessor));
        }

        public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context)
        {
            var userAgent = _httpContextAccessor.HttpContext.Request.Headers["User-Agent"].ToString();
            var settings = context.Parameters.Get<BrowserFilterSettings>();
            return Task.FromResult(settings.AllowedBrowsers.Any(userAgent.Contains));
        }
    }

 string data = null;
var result = data ?? "value";

if (data == null)
{
    data = "value";
}
var result = data;

class Response
{
    public string Result { set; get; }
    public int Code { set; get; }
}

 
class WebRequest
{
    public Response GetDataFromWeb(string url)
    {
        // ...
        return new Response { Result = null };
    }
}

 var webData = new WebRequest().GetDataFromWeb("https://www.dntips.ir/");
if (webData != null && webData.Result != null)
{
    Console.WriteLine(webData.Result);
}

 if (webData?.Result != null)
{
    Console.WriteLine(webData.Result);
}

 if (x != null)
{
   x.Dispose();
}

 x?.Dispose();

 var copy = OnMyEvent;
if (copy != null)
{
   copy(this, new EventArgs());
}

 OnMyEvent?.Invoke(this, new EventArgs());

 var code = webData?.Code;

 if (webData?.Code > 0)
{

}

 int count = response?.Results?.Count ?? 0;

 int? x = 10;
//var value = x?.Value; // invalid
Console.WriteLine(x?.ToString());

 if (response != null && response.Results != null && response.Results.Addresses != null
  && response.Results.Addresses[0] != null && response.Results.Addresses[0].Zip == "63368")
{

}

 if(response?.Results?.Addresses?[0]?.Zip == "63368")
{

}

 public void DoSomething(Customer customer)
{
    string address = customer?.Employees
                  ?.SingleOrDefault(x => x.IsAdmin)?.Address?.ToString();
    SendPackage(address);
}

 public void DoSomething(Customer customer)
{
   Contract.Requires(customer != null); 
   string address = customer.GetAdminAddress();
   SendPackage(address);
}

// ...

app.UseHttpsRedirection();

app.MapGet("/api/authors", async (MinimalBlogDbContext ctx) =>
{
    var authors = await ctx.Authors.ToListAsync();
    return authors;
});

app.Run();

//...

app.UseHttpsRedirection();

//...

app.MapPost("/api/authors", async (MinimalBlogDbContext ctx, AuthorDto authorDto) =>
{
    var author = new Author();
    author.FirstName = authorDto.FirstName;
    author.LastName = authorDto.LastName;
    author.Bio = authorDto.Bio;
    author.DateOfBirth = authorDto.DateOfBirth;

    ctx.Authors.Add(author);
    await ctx.SaveChangesAsync();

    return author;
});

app.Run();

internal record AuthorDto(string FirstName, string LastName, DateTime DateOfBirth, string? Bio);

using Microsoft.EntityFrameworkCore;
using MinimalBlog.Dal;

namespace MinimalBlog.Api.Extensions;

public static class ServiceCollectionExtensions
{
    public static IServiceCollection AddApplicationServices(this IServiceCollection services,
        WebApplicationBuilder builder)
    {
        if (builder == null)
        {
            throw new ArgumentNullException(nameof(builder));
        }

        builder.Services.AddEndpointsApiExplorer();
        builder.Services.AddSwaggerGen();

        var connectionString = builder.Configuration.GetConnectionString("Default");
        builder.Services.AddDbContext<MinimalBlogDbContext>(opt => opt.UseSqlServer(connectionString));

        return services;
    }
}

namespace MinimalBlog.Api.Extensions;

public static class WebApplicationExtensions
{
    public static WebApplication ConfigureApplication(this WebApplication app)
    {
        if (app == null)
        {
            throw new ArgumentNullException(nameof(app));
        }

        if (app.Environment.IsDevelopment())
        {
            app.UseSwagger();
            app.UseSwaggerUI();
        }

        app.UseHttpsRedirection();

        return app;
    }
}

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddApplicationServices(builder);

var app = builder.Build();
app.ConfigureApplication();

    [DataContract]
    public class Book
    {
        [DataMember]
        public int Code { get; set; }

        [DataMember]
        public string Title { get; set; }

        [DataMember]
        public string Author { get; set; }
    }

   [ServiceContract]
    public interface IBookService
    {
        [OperationContract( AsyncPattern = true )]
        IAsyncResult BeginGetAllBook( AsyncCallback callback, object state );

        IEnumerable<Book> EndGetAllBook( IAsyncResult asyncResult ); 
    }

[OperationContract]
IEnumerable<Book> GetAllBook(int code , AsyncCallback callback, object state );

 public class CompletedAsyncResult<TEntity> : IAsyncResult where TEntity : class , new()
    {
        public IList<TEntity> Result
        {
            get
            {
                return _result;
            }
            set
            {
                _result = value;
            }
        }
        private IList<TEntity> _result;

        public CompletedAsyncResult( IList<TEntity> data )
        {
            this.Result = data;
        }

        public object AsyncState
        {
            get
            {
                return ( IList<TEntity> )Result;
            }
        }

        public WaitHandle AsyncWaitHandle
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public bool CompletedSynchronously
        {
            get
            {
                return true;
            }
        }

        public bool IsCompleted
        {
            get
            {
                return true;
            }
        }
    }

 public class BookService : IBookService
    {
        public BookService()
        {
            ListOfBook = new List<Book>();
        }

        public List<Book> ListOfBook
        {
            get;
            private set;
        }

        private List<Book> CreateListOfBook()
        {
            Parallel.For( 0, 10000, ( int counter ) =>
            {
                ListOfBook.Add( new Book()
                {
                    Code = counter,
                    Title = String.Format( "Book {0}", counter ),
                    Author = "Masoud Pakdel"
                } );
            } );

            return ListOfBook;
        }

        public IAsyncResult BeginGetAllBook( AsyncCallback callback, object state )
        {
            var result = CreateListOfBook();
            return new CompletedAsyncResult<Book>( result );
        }

        public IEnumerable<Book> EndGetAllBook( IAsyncResult asyncResult )
        {
            return ( ( CompletedAsyncResult<Book> )asyncResult ).Result;
        }
    }

[System.Diagnostics.DebuggerStepThroughAttribute()]
    [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")]
    public partial class BookServiceClient : System.ServiceModel.ClientBase<UI.BookService.IBookService>, UI.BookService.IBookService {
        
        public BookServiceClient() {
        }
        
        public BookServiceClient(string endpointConfigurationName) : 
                base(endpointConfigurationName) {
        }
        
        public BookServiceClient(string endpointConfigurationName, string remoteAddress) : 
                base(endpointConfigurationName, remoteAddress) {
        }
        
        public BookServiceClient(string endpointConfigurationName, System.ServiceModel.EndpointAddress remoteAddress) : 
                base(endpointConfigurationName, remoteAddress) {
        }
        
        public BookServiceClient(System.ServiceModel.Channels.Binding binding, System.ServiceModel.EndpointAddress remoteAddress) : 
                base(binding, remoteAddress) {
        }
        
        public UI.BookService.Book[] BeginGetAllBook() {
            return base.Channel.BeginGetAllBook();
        }
    }

System.ServiceModel.ClientBase<UI.BookService.IBookService>

 PM> Install-Package Trirand.jqGrid

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>@ViewBag.Title - My ASP.NET Application</title>
    
    <link href="~/Content/themes/base/jquery.ui.all.css" rel="stylesheet" />
    <link href="~/Content/jquery.jqGrid/ui.jqgrid.css" rel="stylesheet" />
    <link href="~/Content/Site.css" rel="stylesheet" type="text/css" />
</head>
<body>
    <div>
        @RenderBody()
    </div>

    <script src="~/Scripts/jquery-1.7.2.min.js"></script>
    <script src="~/Scripts/jquery-ui-1.8.11.min.js"></script>
    <script src="~/Scripts/i18n/grid.locale-fa.js"></script>
    <script src="~/Scripts/jquery.jqGrid.min.js"></script>

    @RenderSection("Scripts", required: false)
</body>
</html>

.ui-widget {
}

/*how to move jQuery dialog close (X) button from right to left*/
.ui-jqgrid .ui-jqgrid-caption-rtl {
    text-align: center !important;
}

.ui-dialog .ui-dialog-titlebar-close {
    left: .3em !important;
}

.ui-dialog .ui-dialog-title {
    margin: .1em 0 .1em .8em !important;
    direction: rtl !important;
    float: right !important;
}

namespace jqGrid01.Models
{
    public class Product
    {
        public int Id { set; get; }
        public string Name { set; get; }
        public decimal Price { set; get; }
        public bool IsAvailable { set; get; }
    }
}

using System.Collections.Generic;

namespace jqGrid01.Models
{
    public class JqGridData
    {
        public int Total { get; set; }

        public int Page { get; set; }

        public int Records { get; set; }

        public IList<JqGridRowData> Rows { get; set; }

        public object UserData { get; set; }
    }

    public class JqGridRowData
    {
        public int Id { set; get; }
        public IList<string> RowCells { set; get; }
    }
}

@{
    ViewBag.Title = "Index";
}

<div dir="rtl" align="center">
    <div id="rsperror"></div>
    <table id="list" cellpadding="0" cellspacing="0"></table>
    <div id="pager" style="text-align:center;"></div>
</div>

@section Scripts
{
    <script type="text/javascript">
        $(document).ready(function () {
            $('#list').jqGrid({
                caption: "آزمایش اول",
                //url from wich data should be requested
                url: '@Url.Action("GetProducts","Home")',
                //type of data
                datatype: 'json',
                jsonReader: { 
                    root: "Rows",
                    page: "Page",
                    total: "Total",
                    records: "Records",
                    repeatitems: true,
                    userdata: "UserData",
                    id: "Id",
                    cell: "RowCells"
                },
                //url access method type
                mtype: 'GET',
                //columns names
                colNames: ['شماره', 'نام محصول', 'موجود است', 'قیمت'],
                //columns model
                colModel: [
                { name: 'Id', index: 'Id', align: 'right', width: 50, sorttype: "number" },
                { name: 'Name', index: 'Name', align: 'right', width: 300 },
                { name: 'IsAvailable', index: 'IsAvailable', align: 'center', width: 100, formatter: 'checkbox' },
                { name: 'Price', index: 'Price', align: 'center', width: 100, sorttype: "number" }
                ],
                //pager for grid
                pager: $('#pager'),
                //number of rows per page
                rowNum: 10,
                rowList: [10, 20, 50, 100],
                //initial sorting column
                sortname: 'Id',
                //initial sorting direction
                sortorder: 'asc',
                //we want to display total records count
                viewrecords: true,
                altRows: true,
                shrinkToFit: true,
                width: 'auto',
                height: 'auto',
                hidegrid: false,
                direction: "rtl",
                gridview: true,
                rownumbers: true,
                footerrow: true,
                userDataOnFooter: true,
                loadComplete: function() {
                    //change alternate rows color
                    $("tr.jqgrow:odd").css("background", "#E0E0E0");
                },
                loadError: function(xhr, st, err) {
                     jQuery("#rsperror").html("Type: " + st + "; Response: " + xhr.status + " " + xhr.statusText);
                }
                //, loadonce: true
            })
            .jqGrid('navGrid', "#pager",
            {
                edit: false, add: false, del: false, search: false,
                refresh: true
            })
            .jqGrid('navButtonAdd', '#pager',
            {
                caption: "تنظیم نمایش ستون‌ها", title: "Reorder Columns",
                onClickButton: function() {
                     jQuery("#list").jqGrid('columnChooser');
                }
            });
        });
    </script>
}
 

ts.p.jsonReader = $.extend(true,{
root: "rows",
page: "page",
total: "total",
records: "records",
repeatitems: true,
cell: "cell",
id: "id",
userdata: "userdata",
subgrid: {root:"rows", repeatitems: true, cell:"cell"}
},ts.p.jsonReader);

 PM> Install-Package DynamicQuery

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Web.Mvc;
using jqGrid01.Models;
using jqGrid01.Extensions; // for dynamic OrderBy

namespace jqGrid01.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        public ActionResult GetProducts(string sidx, string sord, int page, int rows)
        {
            var list = ProductDataSource.LatestProducts;

            var pageIndex = page - 1;
            var pageSize = rows;
            var totalRecords = list.Count;
            var totalPages = (int)Math.Ceiling(totalRecords / (float)pageSize);

            var products = list.AsQueryable()
                               .OrderBy(sidx + " " + sord)
                               .Skip(pageIndex * pageSize)
                               .Take(pageSize)
                               .ToList();

            var jqGridData = new JqGridData
            {
                UserData = new // نمایش در فوتر
                {
                    Name = "جمع صفحه",
                    Price = products.Sum(x => x.Price)
                },
                Total = totalPages,
                Page = page,
                Records = totalRecords,
                Rows = (products.Select(product => new JqGridRowData
                                                {
                                                    Id = product.Id,
                                                    RowCells = new List<string>
                                                    {
                                                        product.Id.ToString(CultureInfo.InvariantCulture),
                                                        product.Name,
                                                        product.IsAvailable.ToString(),
                                                        product.Price.ToString(CultureInfo.InvariantCulture)
                                                    }
                                                })).ToList()
            };
            return Json(jqGridData, JsonRequestBehavior.AllowGet);
        }
    }
}