How To Create ASP.NET Web API GET, POST, PUT, and DELETE

namespace WebAPICURD_Demo.Models
{
    using System;
    using System.Collections.Generic;
    public partial class Employee
    {
        public int Employee_Id { get; set; }
        public string First_Name { get; set; }
        public string Last_Name { get; set; }
        public Nullable<decimal> Salary { get; set; }
        public string Joing_Date { get; set; }
        public string Department { get; set; }
    }
}

Step 4. Right-click on the Controllers folder, select Add, then choose Controller as shown in the below screenshot.

Screenshot 1

After clicking on the controller, a window will appear. Choose Web API 2 Controller-Empty and click on Add.

After clicking on Add another window will appear with DefaultController. Change the name to EmployeeController then click on Add. EmployeeController will be added under the Controllers folder. Remember don’t change the Controller suffix for all controllers, change only highlight, and instead of Default just change Home as shown in the below screenshot.

Complete code for API controller

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using WebAPICURD_Demo.Models;
namespace WebAPICURD_Demo.Controllers
{
    public class EmployeeController : ApiController
    {
        public IEnumerable<Employee> GetEmployees()
        {
            using (EmployeeEntities db = new EmployeeEntities())
            {
                return db.Employees.ToList();
            }
        }
        public HttpResponseMessage GetEmployeeById(int id)
        {
            using (EmployeeEntities db = new EmployeeEntities())
            {
                var entity = db.Employees.FirstOrDefault(e => e.Employee_Id == id);
                if (entity == null)
                {
                    return Request.CreateErrorResponse(HttpStatusCode.NotFound, "Employee with id=" + id.ToString() + " not found");
                }
                else
                {
                    return Request.CreateResponse(HttpStatusCode.OK, entity);
                }
            }
        }
        public HttpResponseMessage Post([FromBody] Employee employee)
        {
            try
            {
                using (EmployeeEntities db = new EmployeeEntities())
                {
                    db.Employees.Add(employee);
                    db.SaveChanges();
                    var message = Request.CreateResponse(HttpStatusCode.Created, employee);
                    message.Headers.Location = new Uri(Request.RequestUri + employee.Employee_Id.ToString());
                    return message;
                }
            }
            catch (Exception ex)
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ex);
            }
        }
        public HttpResponseMessage Delete(int id)
        {
            using (EmployeeEntities db = new EmployeeEntities())
            {
                var entity = db.Employees.FirstOrDefault(e => e.Employee_Id == id);
                if (entity == null)
                {
                    return Request.CreateErrorResponse(HttpStatusCode.NotFound, "Employee with id=" + id.ToString() + "not found to delete");
                }
                else
                {
                    db.Employees.Remove(entity);
                    db.SaveChanges();
                    return Request.CreateResponse(HttpStatusCode.OK);
                }
            }
        }
        public HttpResponseMessage Put(int id, [FromBody] Employee employee)
        {
            using (EmployeeEntities db = new EmployeeEntities())
            {
                try
                {
                    var entity = db.Employees.FirstOrDefault(e => e.Employee_Id == id);
                    if (entity == null)
                    {
                        return Request.CreateErrorResponse(HttpStatusCode.NotFound, "Employee with id=" + id.ToString() + "not found to update");
                    }
                    else
                    {
                        entity.First_Name = employee.First_Name;
                        entity.Last_Name = employee.Last_Name;
                        entity.Salary = employee.Salary;
                        entity.Joing_Date = employee.Joing_Date;
                        entity.Department = employee.Department;
                        db.SaveChanges();
                        return Request.CreateResponse(HttpStatusCode.OK, entity);
                    }
                }
                catch (Exception ex)
                {
                    return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ex);
                }
            }
        }
    }
}

Step 5. Build a project and run the project by pressing ctrl+F5.

URL: portnumeber/api/controllerName

Output

URL: portnumeber/api/controllerName/id (search customer by id)

Output

Conclusion

I have created an ASP.NET Web API to perform GET, POST, PUT, and DELETE operations. It has been tested on Fiddler. I hope this will be helpful for beginners.