WebApi CRUD Operation- Step by step ~ Dotnet Guru ~

In this tutorial, I am assuming you have basic knowledge of asp.net MVC, Web Api, Entity Framework.

1- Open Visual Studio 2015. Create a new Webapi project.

2- Add a new WebApi Controller named EmployeeController.cs.

3- Add a Repository Folder in the solution. add a IEmployeeRepo.cs interface and EmployeeRepo.cs class in the folder. (See above image)

4- Create Database and table in Sql server. below is the script.

CREATE DATABASE [EmployeeDB]

USE [EmployeeDB]
CREATE TABLE [dbo].[tblEmployee](
 [EmpId] [int] IDENTITY(1,1) NOT NULL,
 [FirstName] [varchar](50) NULL,
 [LastName] [varchar](50) NULL,
 CONSTRAINT [PK_tblEmployee] PRIMARY KEY CLUSTERED 
(
 [EmpId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

SET IDENTITY_INSERT [dbo].[tblEmployee] ON 
INSERT [dbo].[tblEmployee] ([EmpId], [FirstName], [LastName]) VALUES (1, N'Suraj', N'Kumar')
INSERT [dbo].[tblEmployee] ([EmpId], [FirstName], [LastName]) VALUES (2, N'Rahul', N'Raj')
INSERT [dbo].[tblEmployee] ([EmpId], [FirstName], [LastName]) VALUES (3, N'Amit', N'Kumar')
SET IDENTITY_INSERT [dbo].[tblEmployee] OFF

5- Add EmployeeModel.cs class in the Model Folder.

6- Here we are using Database first approach for Entity framework so you need to add Datamodel file (.edmx).

7- Now add the below code in IEmployeeRepo.cs file.

    public interface IEmployeeRepo
    {
        List<EmployeeModel> GetAllEmp();
        void AddEmployee(EmployeeModel entity);
        void DeleteEmployee(int id);
        void UpdateEmployee(int id, EmployeeModel model);
        EmployeeModel FindByEmpId(int Id);
    }

8- Implement this interface in EmployeeRepo.cs class.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using EmployeeWeb.Models;

namespace EmployeeWeb.Repository
{
    public class EmployeeRepo : IEmployeeRepo
    {
        EmployeeDBEntities EmpContext;
        List<EmployeeModel> EmpObj = new List<EmployeeModel>();
        public EmployeeRepo()
        {
            EmpContext = new EmployeeDBEntities();
        }

        public List<EmployeeModel> GetAllEmp()
        {
            return MapList(EmpContext.tblEmployees.ToList());
        }

        public List<EmployeeModel> MapList(List<tblEmployee> model)
        {
            List<EmployeeModel> obj = new List<EmployeeModel>();
            foreach (var item in model)
            {
                EmployeeModel emp = new Models.EmployeeModel();
                emp.EmpId = item.EmpId;
                emp.FirstName = item.FirstName;
                emp.LastName = item.LastName;
                
                obj.Add(emp);

            }
            return obj;
        }

        public EmployeeModel FindByEmpId(int Id)
        {
            var result = (from r in EmpContext.tblEmployees where r.EmpId == Id select r).FirstOrDefault();
            return MapEntityToModelModel(result);
        }

        public EmployeeModel MapEntityToModelModel(tblEmployee emp)
        {
            EmployeeModel model = new Models.EmployeeModel();
            model.EmpId = emp.EmpId;
            model.FirstName = emp.FirstName;
            model.LastName = emp.LastName;
            return model;
        }


        public void AddEmployee(EmployeeModel model)
        {
            EmpContext.tblEmployees.Add(MapModelToEntityModel(model));
            EmpContext.SaveChanges();
        }

        public tblEmployee MapModelToEntityModel(EmployeeModel emp)
        {
            tblEmployee model = new Models.tblEmployee();
            //model.EmpId = emp.EmpId;
            model.FirstName = emp.FirstName;
            model.LastName = emp.LastName;
            return model;
        }


        public void DeleteEmployee(int id)
        {
            var emp = EmpContext.tblEmployees
                 .Where(s => s.EmpId == id)
                 .FirstOrDefault();

            EmpContext.Entry(emp).State = System.Data.Entity.EntityState.Deleted;
            EmpContext.SaveChanges();
        }

        public void UpdateEmployee(int id, EmployeeModel model)
        {          
            var existingEmp = EmpContext.tblEmployees.Where(s => s.EmpId == id)
                                                   .FirstOrDefault<tblEmployee>();
            if (existingEmp != null)
            {
                existingEmp.FirstName = model.FirstName;
                existingEmp.LastName = model.LastName;
                EmpContext.Entry(existingEmp).State = System.Data.Entity.EntityState.Modified;
                EmpContext.SaveChanges();
            }
        }
    }
}

9- Now you need to call your repository functions from Employee api controller.

using System.Net;
using System.Net.Http;
using System.Web.Http;
using EmployeeWeb.Models;
using EmployeeWeb.Repository;
using System.Web.Http.Cors;

namespace EmployeeWeb.Controllers
{
    [EnableCors(origins: "http://localhost:4200", headers: "*", methods: "*")]
    public class EmployeeController : ApiController
    {
        public IEmployeeRepo repository = null;   
        public EmployeeController()
        {
            repository = new EmployeeRepo();
        }

        // GET: api/Employee
        public HttpResponseMessage Get()
        {
            var result = repository.GetAllEmp();
            return Request.CreateResponse(HttpStatusCode.OK, result);
        }

        // GET: api/Employee/5
        public HttpResponseMessage Get(int id)
        {
            var result = repository.FindByEmpId(id);

            return Request.CreateResponse(HttpStatusCode.OK, result);
        }

        // POST: api/Employee
        public HttpResponseMessage Post(EmployeeModel model)
        {
            repository.AddEmployee(model);
            return Request.CreateResponse(HttpStatusCode.Created);
        }

        // PUT: api/Employee/5
        public HttpResponseMessage Put(int id, EmployeeModel model)
        {
            repository.UpdateEmployee(id, model);
            return Request.CreateResponse(HttpStatusCode.OK);
        }

        // DELETE: api/Employee/5
        public HttpResponseMessage Delete(int id)
        {
            repository.DeleteEmployee(id);
            return Request.CreateResponse(HttpStatusCode.OK);
        }
    }
}

10- Add some extraa code in Register function of Webapi config to return api data in json format and to enable CORS.

   public static void Register(HttpConfiguration config)
        {
            config.EnableCors(); // Enables CORS

            // Web API configuration and services
            // Configure Web API to use only bearer token authentication.
            config.SuppressDefaultHostAuthentication();
            config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
            config.Formatters.Remove(config.Formatters.XmlFormatter);
        }