Data is Null. This method or property cannot be called on Null values

 Data is Null. This method or property cannot be called on Null values

Issue: 

Data is Null. This method or property cannot be called on Null values

Solution:

For columns that are nullable in your DB tables:

Wrong

 public string Memo { get; set; }

Correct: 

 public string? Memo { get; set; }

Hope this will help you and save your time.

Enjoy !!!

:)

Explicit construction of entity type '###' in query is not allowed.

Explicit construction of entity type '###' in query is not allowed.

Issue

Explicit construction of entity type '###' in query is not allowed.

Solution

var result = from ev in db.Events
 join ea in db.EventAttendees on ev.EventId equals ea.EventId
 where ea.UserId == userid
 select new VMEvent // Here Don't use actual entity class name, Create new view model class
 {
  EventName = ev.EventName,
  EventAttendeeSubmittedDate = ea.SubmittedDate.ToString(),
  Place = ev.Place, 
  EventAttendeeNoofMembers = ea.noofMembers.ToString() 
  }; 

var arrayResult = result.ToArray();
var listResult = result.ToList();
 

  

Hope this will help you and save your time.

Enjoy !!!

:)

Code First Migration in ASP.Net Core

Code First Migration in ASP.Net Core

Generally we create database first and then we create data model classes in project, and while we publish application we need to take care about database creation and table.

Code first, its approach that we first create data model classes and code itself create database and while publishing application, we don't need to take care about database and its tables, code automatically manage.

While executing code first migration command in .Net Core C#, we are facing some issues sometimes, here I faced some issues and found some solutions as below.

Issue 1

Getting error, while executing command 

Add-Migration -Context "DatabaseContext" 

 Unable to create an object of type 'DatabaseContext'. Add an implementation of 'IDesignTimeDbContextFactory<DatabaseContext>' to the project, or see https://go.microsoft.com/fwlink/?linkid=851728 for additional patterns supported at design time.

Solution 

public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<DatabaseContext>
{
 public DatabaseContext CreateDbContext(string[] args)
 {
  IConfigurationRoot configuration = new ConfigurationBuilder()
   .SetBasePath(Directory.GetCurrentDirectory())
   .AddJsonFile("appsettings.json")
   .Build();
  var builder = new DbContextOptionsBuilder<DatabaseContext>();
  var connectionString = configuration.GetConnectionString("dbConStr");
  builder.UseSqlServer(connectionString);
  return new DatabaseContext(builder.Options);
 }
}

Issue 2

Getting error, while executing below command

Add-Migration -Name "Migration Name" -Context "DatabaseContext"

GenericArguments[0], 'SampleWebAPI.Migrations.DatabaseContext', on 'Microsoft.EntityFrameworkCore.Design.IDesignTimeDbContextFactory`1[TContext]' violates the constraint of type 'TContext'.

Solution 

1. First remove migration folder (if any) from project which was created by above command

Issue 3

Getting error, while executing command 

Update-Database 

More than one DbContext was found. Specify which one to use. Use the '-Context' parameter for PowerShell commands and the '--context' parameter for dotnet commands.

Solution 

Update-Database -Context "DatabaseContext"

Finally

Use below migration commands for .Net Core

1. Add-Migration -Name "Migration Name" -Context "DatabaseContext"

2. Update-Database -Context "DatabaseContext"

Enjoy !!!

:)

Code First Steps in ASP.Net C#

Code First Steps in ASP.Net C#

Generally we create database first and then we create data model classes in project, and while we publish application we need to take care about database creation and table.

Code first, its approach that we first create data model classes and code itself create database and while publishing application, we don't need to take care about database and its tables, code automatically manage.

Lets see, how to work with code first in .Net C#

Steps

1.First provide connection string in web.config file.

<connectionStrings>
    <add name="conDemoDB" connectionString="data source=ServerName; initial catalog=dbName; user id=username; password=password;" providerName="System.Data.EntityClient"/>
  </connectionStrings>

2. Create data model classes as per your requirement

3. Install Entity Framework using nu-get package installer or command 

4. Create DataContext Class

using System.Data.Entity;
using System.Data.Entity.Infrastructure;
 
namespace DemoApp.Reporsitory
{
    public class dataContext : DbContext
    {
        public dataContext()
            : base("name=conDemoDB")
        {
        }
 
        public virtual DbSet<Menu> Menus { get; set; }
        public virtual DbSet<MenuItem> MenuItems { get; set; }
    }
}

5. Open Package Manager Console from Tools -> NuGet Package Manager

1. Enable-Migrations  

2. Add-Migration "Comments"

3. Update-Database -Verbose 

Once command executes successfully, you can open database and check that tables are created.

for more detail, https://docs.microsoft.com/en-us/ef/ef6/modeling/code-first/migrations/automatic

Enjoy !!!

:)

Country - State - City Dropdown - Binding - Change Event using JQuery Ajax

Country - State - City Dropdown - Binding - Change Event using JQuery Ajax

Here I have created blog, how to use dropdown cascading like, country, state and city.

I have use some generic code.

To bind state and city dropdown I have used ajax call.

 Database Script
 

/****** Object:  Table [dbo].[Country]   ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Country](
 [CountryId] [uniqueidentifier] NOT NULL,
 [CountryName] [nvarchar](50) NOT NULL,
 [CountryCode] [nvarchar](5) NULL,
 [CountryPhoneCode] [nvarchar](7) NULL,
 [Status] [nvarchar](10) NOT NULL,
 [CreatedBy] [uniqueidentifier] NOT NULL,
 [CreatedDate] [datetime] NOT NULL CONSTRAINT [DF_Country_CreatedDate]  DEFAULT (getdate()),
 [UpdatedBy] [uniqueidentifier] NULL,
 [UpdatedDate] [datetime] NOT NULL CONSTRAINT [DF_Country_UpdatedDate]  DEFAULT (getdate()),
 CONSTRAINT [PK_Country] PRIMARY KEY CLUSTERED 
(
 [CountryId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

/****** Object:  Table [dbo].[State]    ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[State](
 [StateId] [uniqueidentifier] NOT NULL,
 [CountryId] [uniqueidentifier] NOT NULL,
 [StateName] [nvarchar](50) NOT NULL,
 [StateCode] [nvarchar](5) NULL,
 [Status] [nvarchar](10) NOT NULL,
 [CreatedBy] [uniqueidentifier] NOT NULL,
 [CreatedDate] [datetime] NOT NULL CONSTRAINT [DF_State_CreatedDate]  DEFAULT (getdate()),
 [UpdatedBy] [uniqueidentifier] NULL,
 [UpdatedDate] [datetime] NOT NULL CONSTRAINT [DF_State_UpdatedDate]  DEFAULT (getdate()),
 CONSTRAINT [PK_QState] PRIMARY KEY CLUSTERED 
(
 [StateId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO


/****** Object:  Table [dbo].[City]   ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[City](
 [CityId] [uniqueidentifier] NOT NULL,
 [StateId] [uniqueidentifier] NOT NULL,
 [CityName] [nvarchar](50) NOT NULL,
 [CityCode] [nvarchar](5) NULL,
 [CityPhoneCode] [nvarchar](7) NULL,
 [Status] [nvarchar](10) NOT NULL,
 [CreatedBy] [uniqueidentifier] NOT NULL,
 [CreatedDate] [datetime] NOT NULL CONSTRAINT [DF_City_CreatedDate]  DEFAULT (getdate()),
 [UpdatedBy] [uniqueidentifier] NULL,
 [UpdatedDate] [datetime] NOT NULL CONSTRAINT [DF_City_UpdatedDate]  DEFAULT (getdate()),
 CONSTRAINT [PK_City] PRIMARY KEY CLUSTERED 
(
 [CityId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO


ALTER TABLE [dbo].[City]  WITH CHECK ADD  CONSTRAINT [FK_City_State] FOREIGN KEY([StateId])
REFERENCES [dbo].[State] ([StateId])
GO
ALTER TABLE [dbo].[City] CHECK CONSTRAINT [FK_City_State]
GO
ALTER TABLE [dbo].[State]  WITH CHECK ADD  CONSTRAINT [FK_State_Country] FOREIGN KEY([CountryId])
REFERENCES [dbo].[Country] ([CountryId])
GO
ALTER TABLE [dbo].[State] CHECK CONSTRAINT [FK_State_Country]
GO
ALTER TABLE [dbo].[State]  WITH CHECK ADD  CONSTRAINT [FK_State_QDevCountry] FOREIGN KEY([CountryId])
REFERENCES [dbo].[Country] ([CountryId])
GO
ALTER TABLE [dbo].[State] CHECK CONSTRAINT [FK_State_QDevCountry]
GO
/****** Object:  Table [dbo].[Users]   ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Users](
 [UserId] [uniqueidentifier] NOT NULL,
 [usertype] [nvarchar](10) NOT NULL,
 [Username] [nvarchar](50) NOT NULL,
 [Password] [nvarchar](100) NOT NULL, 
 [FirstName] [nvarchar](40) NULL,
 [LastName] [nvarchar](30) NOT NULL, 
 [AddressLine1] [nvarchar](150) NULL,
 [AddressLine2] [nvarchar](150) NULL,
 [CityId] [uniqueidentifier] NULL,
 [EmailId] [nvarchar](50) NULL,
 [MobileNumber] [nvarchar](15) NULL,
 [HomePhoneNumber] [nvarchar](15) NULL,
 [WorkPhoneNumber1] [nvarchar](15) NULL,
 [WorkPhoneNumber2] [nvarchar](15) NULL,
 [Status] [nvarchar](8) NOT NULL,
 [CreatedBy] [uniqueidentifier] NOT NULL,
 [CreatedDate] [datetime] NULL CONSTRAINT [DF_Users_CreatedDate]  DEFAULT (getdate()),
 [UpdatedBy] [uniqueidentifier] NULL,
 [UpdatedDate] [datetime] NULL CONSTRAINT [DF_Users_UpdatedDate]  DEFAULT (getdate()),
 CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED 
(
 [UserId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

 

  View Model

namespace Demo.ViewModel
{
    public class VMCountry
    {
        public System.Guid CountryId { get; set; }
 
        [Required]
        [DisplayName("Country Name")]
        public string CountryName { get; set; }
 
        [Required]
        [DisplayName("Country Code")]
        public string CountryCode { get; set; }
        public string CountryPhoneCode { get; set; }
        public string Status { get; set; }
        public System.Guid CreatedBy { get; set; }
        public System.DateTime CreatedDate { get; set; }
        public Nullable<System.Guid> UpdatedBy { get; set; }
        public System.DateTime UpdatedDate { get; set; }
    }
}

namespace Demo.ViewModel
{
    public class VMState
    {
        public System.Guid StateId { get; set; }
        public System.Guid CountryId { get; set; }
        public string StateName { get; set; }
        public string StateCode { get; set; }
        public string Status { get; set; }
        public System.Guid CreatedBy { get; set; }
        public System.DateTime CreatedDate { get; set; }
        public Nullable<System.Guid> UpdatedBy { get; set; }
        public System.DateTime UpdatedDate { get; set; }
 
        public List<SelectListItem> CountryList { get; set; }
    }
}

namespace Demo.ViewModel
{
    public class VMCity
    {
        public System.Guid CityId { get; set; }
        public System.Guid StateId { get; set; }
        public string CityName { get; set; }
        public string CityCode { get; set; }
        public string CityPhoneCode { get; set; }
        public string Status { get; set; }
        public System.Guid CreatedBy { get; set; }
        public System.DateTime CreatedDate { get; set; }
        public Nullable<System.Guid> UpdatedBy { get; set; }
        public System.DateTime UpdatedDate { get; set; }
        public List<SelectListItem> CountryList { get; set; }
        public List<SelectListItem> StateList { get; set; }
        public System.Guid CountryId { get; set; }
    }
}

 

namespace Demo.ViewModel
{
    public class VMUser
    {
        public System.Guid UserId { get; set; }
 
        public string usertype { get; set; }
 
        [Required]
        [DisplayName("Username")]
        public string Username { get; set; }
 
        [Required]
        [DataType(DataType.Password)]
        public string Password { get; set; }
        
        [Required]
        [DisplayName("First Name")]
        public string FirstName { get; set; }
 
        [DisplayName("Last Name")]
        public string LastName { get; set; } 
        
        public string AddressLine1 { get; set; }
 
        public string AddressLine2 { get; set; }
 
        public Nullable<System.Guid> CityId { get; set; }
 
        [DisplayName("Email Id")]
        public string EmailId { get; set; }
 
        [DisplayName("Mobile Number")]
        public string MobileNumber { get; set; } 
         
        public string Status { get; set; }
        public System.Guid CreatedBy { get; set; }
        public Nullable<System.DateTime> CreatedDate { get; set; }
        public Nullable<System.Guid> UpdatedBy { get; set; }
        public Nullable<System.DateTime> UpdatedDate { get; set; }
 
 
        //Extra Properties for page view
        public List<SelectListItem> CountryList { get; set; }
        public List<SelectListItem> StateList { get; set; }
        public List<SelectListItem> CityList { get; set; }
 
        public Nullable<System.Guid> Country { get; set; }
        public Nullable<System.Guid> State { get; set; }
    }
}

 

 Use Automapper to map data model and view model.

namespace Demo.Business
{
    public static class AutoMapperConfig
    {
        public static void RegisterMappings()
        { 
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<VMCountry, Country>();
                cfg.CreateMap<Country, VMCountry>();
 
                cfg.CreateMap<VMState, State>();
                cfg.CreateMap<State, VMState>();
 
                cfg.CreateMap<VMCity, City>();
                cfg.CreateMap<City, VMCity>(); 
            });
 
        }
    }
}

Setup with Automapper config in global.asax

namespace Demo.Web
{
    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        { 
            AutoMapperConfig.RegisterMappings();
            
        }
    }
}

Setup Generic class and properties.

namespace Demo.Common
{
    public class ResultResponse<T>
    {
        public bool Success { get; set; } = true;
        public string Message { get; set; }
        public DTResult<T> Data { get; set; }
        public T Datas { get; set; }
        public Dictionary<string, string> Exceptions { get; set; }
    }
 
    public class ResultResponses<T>
    {
        public bool Success { get; set; } = true;
        public string Message { get; set; }
        public T Data { get; set; }
        public Dictionary<string, string> Exceptions { get; set; }
    }
    public class ResultResponseSingle<T>
    {
        public bool Success { get; set; } = true;
        public string Message { get; set; }
        public T Data { get; set; }
        public Dictionary<string, string> Exceptions { get; set; }
    }
}

Business Layer

namespace Demo.Business
{
    public class BLCountry
    {        
        public static ResultResponses<List<VMCountry>> GetCountryListforDDL()
        {
            var exceptions = new Dictionary<string, string>();
            List<VMCountry> data = new List<VMCountry>();
 
            try
            {
                AnroAppEntities db = new AnroAppEntities();
 
                var datas = db.Countries.AsQueryable().OrderBy(c=>c.CountryName).ToList();
 
                var Datas = AutoMapper.Mapper.Map<List<Country>, List<VMCountry>>(datas);
                data = Datas;
            }
            catch (SqlException sqlException)
            {
                exceptions.Add("SqlException", sqlException.Message);
            }
            catch (TaskCanceledException taskCanceledException)
            {
                exceptions.Add("TaskCanceledException", taskCanceledException.Message);
            }
            catch (Exception ex)
            {
                exceptions.Add("Exception", ex.Message);
            }
            return new ResultResponses<List<VMCountry>>
            {
                Exceptions = exceptions,
                Data = data
            };           
        } 
    }
}

namespace Demo.Business
{
    public class BLStates
    {
        public static ResultResponses<List<VMState>> GetStateListforDDL(string CountryId)
        {
            var exceptions = new Dictionary<string, string>();
            
            List<VMState> Data = new List<VMState>();
 
            try
            {
                AnroAppEntities db = new AnroAppEntities();
 
                Guid countryId = new Guid(CountryId);
 
                var datas = db.States.AsQueryable().Where(a => a.CountryId == countryId).OrderBy(c => c.StateName).ToList();
                
                var Datas = AutoMapper.Mapper.Map<List<State>, List<VMState>>(datas);
                Data = Datas;                
 
            }
            catch (SqlException sqlException)
            {
                exceptions.Add("SqlException", sqlException.Message);
            }
            catch (TaskCanceledException taskCanceledException)
            {
                exceptions.Add("TaskCanceledException", taskCanceledException.Message);
            }
            catch (Exception ex)
            {
                exceptions.Add("Exception", ex.Message);
            }
            return new ResultResponses<List<VMState>>
            {
                Exceptions = exceptions,
                Data = Data
            }; 
        } 
    }
}

namespace Demo.Business
{
    public class BLCity
    {
        public static ResultResponses<List<VMCity>> GetCityListforDDL(string StateId)
        {
            var exceptions = new Dictionary<string, string>();
 
            List<VMCity> Data = new List<VMCity>();
 
            try
            {
                AnroAppEntities db = new AnroAppEntities();
 
                Guid stateId = new Guid(StateId);
 
                var datas = db.Cities.AsQueryable().Where(a => a.StateId == stateId).OrderBy(c => c.CityName).ToList();
 
                var Datas = AutoMapper.Mapper.Map<List<City>, List<VMCity>>(datas);
                Data = Datas;
 
            }
            catch (SqlException sqlException)
            {
                exceptions.Add("SqlException", sqlException.Message);
            }
            catch (TaskCanceledException taskCanceledException)
            {
                exceptions.Add("TaskCanceledException", taskCanceledException.Message);
            }
            catch (Exception ex)
            {
                exceptions.Add("Exception", ex.Message);
            }
            return new ResultResponses<List<VMCity>>
            {
                Exceptions = exceptions,
                Data = Data
            }; 
        } 
    }
}

 

namespace Demo.Business
{
    public class BLUsers
    { 
        public static ResultResponse<string> Save(VMUser objData, string AddorUpdate)
        {
            string returnMessage = "";
            var exceptions = new Dictionary<string, string>();
 
            try
            {
                using (var db = new AnroAppEntities())
                {
                    var user = AutoMapper.Mapper.Map<VMUser, User>(objData);
 
                    if (AddorUpdate == "add")
                        db.Users.Add(user);
                    else
                        db.Entry(user).State = System.Data.Entity.EntityState.Modified;
 
 
                    var i = db.SaveChanges();
                    if (i == 1)
                        returnMessage = "success";
                    else
                        returnMessage = "Something wrong";
                }
            }
            catch (System.Data.Entity.Validation.DbEntityValidationException dbEx)
            {
                Exception raise = dbEx;
                foreach (var validationErrors in dbEx.EntityValidationErrors)
                {
                    foreach (var validationError in validationErrors.ValidationErrors)
                    {
                        string message = string.Format("{0}:{1}",
                            validationErrors.Entry.Entity.ToString(),
                            validationError.ErrorMessage);
                        raise = new InvalidOperationException(message, raise);
                    }
                }
                throw raise;
            }
            catch (SqlException sqlException)
            {
                exceptions.Add("SqlException", sqlException.Message);
            }
            catch (TaskCanceledException taskCanceledException)
            {
                exceptions.Add("TaskCanceledException", taskCanceledException.Message);
            }
            catch (Exception ex)
            {
                exceptions.Add("Exception", ex.Message);
            }
            return new ResultResponse<string>
            {
                Exceptions = exceptions,
                Message = returnMessage
            };
        } 
    }
}

Common Controller

using Demo.Business;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
 
namespace Demo.Web.Controllers
{
    public class CommonController : Controller
    {
 
        public static List<SelectListItem> BindCountryList()
        {
            List<SelectListItem> items = new List<SelectListItem>();
            var list = BLCountry.GetCountryListforDDL();
            var statuslist = list.Data.ToList();
            items = statuslist.Select(a => new SelectListItem
            {
                Text = a.CountryName,
                Value = a.CountryId.ToString()
            }).ToList();
            return items;
        }
 
        public static List<SelectListItem> BindStateList(string id)
        {
            List<SelectListItem> items = new List<SelectListItem>();
            var list = BLStates.GetStateListforDDL(id);
            var statuslist = list.Data.ToList();
            items = statuslist.Select(a => new SelectListItem
            {
                Text = a.StateName,
                Value = a.StateId.ToString()
            }).ToList();
            return items;
        }
 
        public static List<SelectListItem> BindCityList(string id)
        {
            List<SelectListItem> items = new List<SelectListItem>();
            var list = BLCity.GetCityListforDDL(id);
            var statuslist = list.Data.ToList();
            items = statuslist.Select(a => new SelectListItem
            {
                Text = a.CityName,
                Value = a.StateId.ToString()
            }).ToList();
            return items;
        }
 
        public JsonResult GetStates(string id)
        {
            List<SelectListItem> datas = new List<SelectListItem>();
            var list = BLStates.GetStateListforDDL(id).Data.ToList(); 
            
            datas = list.Select(a => new SelectListItem
            {
                Text = a.StateName,
                Value = a.StateId.ToString()
            }).ToList();
            datas.Insert(0, new SelectListItem { Text = "Select State", Value = "select" });
            return Json(new SelectList(datas, "Value", "Text"));
        }
 
        public JsonResult GetCity(string id)
        {
            List<SelectListItem> datas = new List<SelectListItem>();
            var list = BLCity.GetCityListforDDL(id).Data.ToList();
 
            datas = list.Select(a => new SelectListItem
            {
                Text = a.CityName,
                Value = a.CityId.ToString()
            }).ToList();
            datas.Insert(0, new SelectListItem { Text = "Select City", Value = "select" });
            return Json(new SelectList(datas, "Value", "Text"));
        }
 
        public ActionResult refreshdata()
        {
            return Json(new { message = "success" }, JsonRequestBehavior.AllowGet);
        }
    }
}

User Controller with Register Action and Save action

namespace Demo.Web.Controllers
{
    public class UserController : Controller
    {         
        
        public ActionResult Register()
        {
            VMUser model = new VMUser();
            model.CountryList = CommonController.BindCountryList();
 
 
            model.CountryList = CommonController.BindCountryList();
            var countryid = model.CountryList.Where(a => a.Text.ToLower() == "india").FirstOrDefault().Value;
            
 
            model.Country = countryid != null ? new Guid(countryid) : Guid.NewGuid();
 
            model.StateList = CommonController.BindStateList(countryid != null ? countryid : Guid.NewGuid().ToString());
            var statedata = model.StateList.Where(s => s.Text.ToLower() == "gujarat").FirstOrDefault();
            var stateid = statedata != null ? statedata.Value : null;
            model.State = stateid != null ? new Guid(stateid) : Guid.NewGuid();
            
 
            model.CityList = CommonController.BindCityList(stateid != null ? stateid : Guid.NewGuid().ToString());
            var citydata = model.CityList.Where(s => s.Text.ToLower() == "ahmedabad").FirstOrDefault();
            var cityid = citydata != null ? citydata.Value : null;
            model.CityId = cityid != null ? new Guid(cityid) : Guid.NewGuid();
            
            
 
            return View(model);
        }
 
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create(VMUser model)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    model.UserId = Guid.NewGuid();
                    model.Status = "Active";
                    model.CreatedBy = Guid.NewGuid();
                    model.CreatedDate = DateTime.Now;
                    model.UpdatedBy = null;
                    model.UpdatedDate = DateTime.Now;
 
                    var data = BLUser.Save(model, "add");
                    if (data.Exceptions.Count > 0)
                    {
                        string error = "";
                        foreach (var keyValuePair in data.Exceptions)
                        {
                            error += keyValuePair.Value;
                        }
                        ModelState.AddModelError("", error);
                    }
 
                    return RedirectToAction("Index");
                }
 
                return View(model);
            }
            catch (Exception ex)
            {                
                ModelState.AddModelError("", ex.Message);
                return View(model);
            }
        }
    }
}

View page

@model Demo.ViewModel.VMUser
@{
    ViewBag.Title = "Register";
}
 
<section class="content">
    <div class="box">
        <div class="box-header with-border">
            <h3 class="box-title">User - Register</h3>
        </div>
        <!-- /.box-header -->
        <div class="box-body">
            <div class="col-md-8">
                @using (Html.BeginForm())
                {
                    @Html.AntiForgeryToken()
 
                    <div>
                        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
                        
                        <div class="row">
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.Username, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.Username, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.Username, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.Password, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.Password, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.Password, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                        </div>
                        <div class="row">
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.FirstName, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.FirstName, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.FirstName, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.LastName, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.LastName, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.LastName, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                        </div>
                        <div class="row">
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.EmailId, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.EmailId, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.EmailId, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.MobileNumber, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.MobileNumber, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.MobileNumber, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                        </div>
 
                        <div class="row">
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.AddressLine1, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.AddressLine1, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.AddressLine1, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-6">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.AddressLine2, htmlAttributes: new { @class = "control-label" })
                                    @Html.EditorFor(model => model.AddressLine2, new { htmlAttributes = new { @class = "form-control" } })
                                    @Html.ValidationMessageFor(model => model.AddressLine2, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                        </div>
 
                        <div class="row">
                            <div class="col-md-4">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.Country, htmlAttributes: new { @class = "control-label" })
                                    @Html.DropDownListFor(model => model.Country, Model.CountryList, "Please select a Country", htmlAttributes: new { @class = "form-control select2", @id = "countryid" })
                                    @Html.ValidationMessageFor(model => model.Country, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-4">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.State, htmlAttributes: new { @class = "control-label" })
                                    @Html.DropDownListFor(model => model.State, Model.StateList, "Please select a State", htmlAttributes: new { @class = "form-control select2", @id = "stateid" })
                                    @Html.ValidationMessageFor(model => model.State, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                            <div class="col-md-4">
                                <div class="form-group">
                                    @Html.LabelFor(model => model.CityId, htmlAttributes: new { @class = "control-label" })
                                    @Html.DropDownListFor(model => model.CityId, Model.CityList, "Please select a City", htmlAttributes: new { @class = "form-control select2", @id = "cityid" })
                                    @Html.ValidationMessageFor(model => model.CityId, "", new { @class = "text-danger validation-msg " })
                                </div>
                            </div>
                        </div>
                        <div class="row">
                            <div class="col-md-10">
                                <div class="form-group">
                                    <input type="submit" value="Create" class="btn btn-primary" />
                                    @Html.ActionLink("Back to List", "Index", null, new { @class = "btn btn-default" })
                                </div>
                            </div>
                        </div>
                    </div>
                }
 
            </div>
        </div> 
    </div>
</section>
 
<script src="~/Content/CustomJS/User.js"></script>

User.js - Ajax call

var sitename = '/demo.web';
 
$(document).ready(function () {
   
    //Country Dropdownlist Selectedchange event
    $("#countryid").change(function () {
        $("#stateid").empty();
        $("#cityid").empty();
        $.ajax({
            type: 'POST',
            url: sitename + '/Common/GetStates',
            dataType: 'json',
            data: { id: $("#countryid").val() },
            success: function (states) {
                $.each(states, function (i, state) {
                    $("#stateid").append('<option value="' + state.Value + '">' +
                            state.Text + '</option>');
                });
 
                $("#cityid").append('<option value="select">Select City</option>');
            },
            error: function (ex) {
                alert('Failed to retrieve states.' + ex);
            }
        });
        return false;
    }); 
 
    //State Dropdownlist Selectedchange event
    $("#stateid").change(function () {
        $("#cityid").empty();
        $.ajax({
            type: 'POST',
            url: sitename + '/Common/GetCity',
            dataType: 'json',
            data: { id: $("#stateid").val() },
            success: function (states) {
                $.each(states, function (i, state) {
                    $("#cityid").append('<option value="' + state.Value + '">' +
                            state.Text + '</option>');
                });
            },
            error: function (ex) {
                alert('Failed to retrieve states.' + ex);
            }
        });
        return false;
    }); 
});

Finally you will get below out put for dropdown

 

Enjoy !!!

:)