Simple way to create dropdwon in MVC with EntityFramework.

Step:1  Create  KeyValuePair Class in ModelLayer

namespace Model

{

    public  class KeyValuePair

    {

        public int Val { get; set; }

        public string label { get; set; }

    }

}

Step:2 Create DropDownModel Model in ModelLayer

using System.Collections.Generic;

namespace Model

{

    public  class DropDownModel

    {

        public int RollNo { get; set; }

        public string Name { get; set; }

       public List<KeyValuePair> KeyValuePair { get; set; }

        public List<KeyValuePair> KeyValuePair1 { get; set; }

        public List<KeyValuePair> KeyValuePair2 { get; set; }

        public List<KeyValuePair> KeyValuePair3 { get; set; }

    }

}

Step:3 Create Class StudentManagement in BussinessLayer.

Step:4 Add Entity in dataLayer.

Step:5 Create Method to get Data from Database using Entity.

using DataLayer;

using Model;

using System.Collections.Generic;

using System.Linq;

namespace BussinessLayer

{

    public class StudentManegament

    {

        public List<KeyValuePair> getDropDownData()

        {

            List<KeyValuePair> keyValuePairs = new List<KeyValuePair>();

            using (var Context = new StudentDBEntities())

            {

                keyValuePairs = (from std in Context.getStudentList() select new KeyValuePair

                {

                    label=std.Name,

                    Val=std.Roll

                }).ToList();

            }

                return keyValuePairs;

        }

    }

}

Step:6 Create Home Controller.

Step:7 Create  Action Method DropDown in Home  Controller.

using BussinessLayer;

using Model;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

namespace DotNetByPriyanshu.Controllers

{

    public class HomeController : Controller

    {

      

        public ActionResult DropDown()

       {

            StudentManegament studentManegament = new StudentManegament();

            DropDownModel dropDownModel = new DropDownModel();

            dropDownModel.KeyValuePair1 = studentManegament.getDropDownData();

            dropDownModel.KeyValuePair2 = studentManegament.getDropDownData();

            dropDownModel.KeyValuePair3 = studentManegament.getDropDownData();

            return View(dropDownModel);

        }

      

    }

}

Step:8 Add View with DropDownModel

@model Model.DropDownModel

@{

    ViewBag.Title = "About";

}

<h2>About</h2>

@using (Html.BeginForm()) 

{

    @Html.AntiForgeryToken()

    

<div class="form-horizontal">

    <h4>DropDownModel</h4>

    <hr />

    @Html.ValidationSummary(true, "", new { @class = "text-danger" })

 

    <div class="form-group">

        <div class="col-md-5">

            @Html.DropDownListFor(x => Model.RollNo, new SelectList(Model.KeyValuePair1, "Val", "label"), "Select1", htmlAttributes: new { @class = "form-control", @id = "DDlRegion" })

            @Html.ValidationMessageFor(x => x.KeyValuePair, "", new { @class = "text-danger" })

        </div>

    </div>   <div class="form-group">

        <div class="col-md-5">

            @Html.DropDownListFor(x => Model.RollNo, new SelectList(Model.KeyValuePair2, "Val", "label"), "Select2", htmlAttributes: new { @class = "form-control", @id = "DDlRegion" })

            @Html.ValidationMessageFor(x => x.KeyValuePair, "", new { @class = "text-danger" })

        </div>

    </div>   <div class="form-group">

        <div class="col-md-5">

            @Html.DropDownListFor(x => Model.RollNo, new SelectList(Model.KeyValuePair3, "Val", "label"), "Select3", htmlAttributes: new { @class = "form-control", @id = "DDlRegion" })

            @Html.ValidationMessageFor(x => x.KeyValuePair, "", new { @class = "text-danger" })

        </div>

    </div>

  

</div>

}

Database

Table StudentInfo:

/****** Object:  Table [dbo].[StudentInfo]    Script Date: 7/23/2019 2:41:02 AM ******/

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

CREATE TABLE [dbo].[StudentInfo](

[Roll] [int] IDENTITY(1,1) NOT NULL,

[Name] [varchar](100) NULL,

[Course] [varchar](100) NULL,

[Mobile] [varchar](100) NULL,

[Address] [varchar](100) NULL,

 CONSTRAINT [PK_StudentInfo] PRIMARY KEY CLUSTERED 

(

[Roll] 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

StoredProcedure [dbo].[getStudentList]:

/****** Object:  StoredProcedure [dbo].[getStudentList]    ******/

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

-- =============================================

-- Author: Dot Net By Priyanshu

-- Create date: 12-12-2018

-- Description: getStudentList

-- =============================================

ALTER PROCEDURE [dbo].[getStudentList]

AS

BEGIN

SET NOCOUNT ON;

SELECT [Roll]

      ,[Name]

      

  FROM [StudentDB].[dbo].[StudentInfo]

END

Console Program for finding Nth Large Salary from List. using Lambda expression/Linq.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DotNetByPriyanshu_App

{

    class Program

    {

        static void Main(string[] args)

        {

            List<TestClass> testClasses = new List<TestClass>();

            for (int i = 0; i < 10; i++)

            {

                TestClass testClass = new TestClass();

                testClass.id = 1 + i;

                testClass.EmpName = "Dot Net By Priyanshu" + i;

                testClass.salary = 20000 + i;

                testClasses.Add(testClass);

            }

             int N = 2; //we can change value according to requirement.

            // It will return 2nd Heigest salary.

            var Nth_HieghtSal = testClasses.OrderByDescending(e => e.salary).Skip(N-1).First();

          //Note : if you want to find n salary then you can simply change the value of N 

        }

    }

    public class TestClass

    {

        public int id { get; set; }

        public string EmpName { get; set; }

        public int salary { get; set; }

}

}

Create filter to redirect page to login page on direct hit URL in MVC.

Steps:

1. Add a new folder Name it Filter.

2. Add a new class name it NoDirectAccessAttribute.  

3. Inherit ActionFilterAttribute

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

using System.Web.Routing;

namespace DotNetByPriyanshu.Filter

{

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]

    public class NoDirectAccessAttribute : ActionFilterAttribute

    {

        public override void OnActionExecuting(ActionExecutingContext filterContext)

        {

            if (filterContext.HttpContext.Request.UrlReferrer == null ||

                        filterContext.HttpContext.Request.Url.Host != filterContext.HttpContext.Request.UrlReferrer.Host)

            {

                filterContext.Result = new RedirectToRouteResult(new

                               RouteValueDictionary(new { controller = "Login", action = "Login", area = "" }));

            }

        }

    }

}

Uses:- use as an attribute over all Controller.

like:- [NoDirectAccessAttribute]

Reverse String with two different logic using C#

               Reverse String with two different logic  using C#

                                                Program.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Enter String For Reverse.");

            string str = Console.ReadLine();

            string rev = Calculation.revString1(str);

            Console.WriteLine("Orignal String = " + str);

            Console.WriteLine("Reversed String1 = " + rev);

            string rev1 = Calculation.revString2(str);

            Console.WriteLine("Reversed String2 = " + rev1);

            Console.ReadLine();

        }

    }

} 

                                              Calculation.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    public static class Calculation

    {

        public static string revString1(string str)

        {

            char[] charArray = str.ToCharArray();

            char[] rev = new char[charArray.Length];

            int j = 0;

            for (int i = charArray.Length - 1; i >= 0; i--)

            {

                rev[j++] = charArray[i];

            }

            return new string(rev);

        }

        public static string revString2(string Str)

        {

            int L;

            string Revstr = string.Empty;

            L = Str.Length - 1;

            while (L >= 0)

            {

                Revstr = Revstr + Str[L];

                L--;

            }

            return Revstr;

        }

    }

}

HCF Calculation Over integer Array using c#.

HCF Calculation Over integer Array using c#.

                                                       Program.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Enter number");

            int num = int.Parse(Console.ReadLine());

            int[] Arr = new int[num];

            Console.WriteLine("Enter " + num + "number");

            for (int i = 0; i < num; i++)

            {

                Arr[i] = int.Parse(Console.ReadLine());

            }

            Console.WriteLine("HCF Array");

            int result = Arr[0];

            for (int i = 1; i < Arr.Length; i++)

            {

                result = Calculation.Calculate(result, Arr[i]);

            }

            Console.WriteLine(result);

            Console.ReadLine();

        }

    }

} 

                                                   Calculation.cs

                    //HCF Calculation Over integer Array using c#.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    public static class Calculation

    {

        public static int Calculate(int result, int value)

        {

            while (value > 0)

            {

                int temp = value;

               value = result % value;

                result = temp;

            }

            return result;

     }

    }

}

Maximum occurrence of number in an integer Array using C#

Maximum occurrence of number in an integer Array using C#

                                               Program.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Enter number");

            int num = int.Parse(Console.ReadLine());

            int[] Arr = new int[num];

            Console.WriteLine("Enter " + num + "number");

            for (int i = 0; i < num; i++)

            {

                Arr[i] = int.Parse(Console.ReadLine());

            }

            int[] result = new int[2];

            result = Calculation.MaxOccurance(Arr);

            Console.Write("Number:- " + result[0] + " Occurance:- " + result[1]);

            Console.ReadLine();

        }

    }

} 

                                              Calculation.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CalculationApp

{

    public static class Calculation

    {

//Method for Calculating the maximum occurrence of number in array.

        public static int[] MaxOccurance(int[] Arr)

        {

            int Number = 0;

            int MaxOccurance = 0;

            int Search = 0;

            for (int i = 0; i < Arr.Length; i++)

            {

                int count = 0;

                Search = Arr[i];

                for (int j = 0; j < Arr.Length; j++)

                {

                    if (Arr[i] == Arr[j])

                    {

                        count++;

                    }

                }

                if (count > MaxOccurance)

                {

                    MaxOccurance = count;

                    Number = Arr[i];

                }

            }

            int[] result = new int[2];

            result[0] = Number;

            result[1] = MaxOccurance;

            return result;

        }

    }

}