CRUD stands for Create ,Read, Update and Delete, these
are four basic standard database operations . How we implement these CRUD
operations in asp.net web api.
create webapi application
In
the New ASP.NET MVC 4 Project dialog, select Web API and click OK.
I will take one sample
Employee table with valid data
create one Employee table in database
Create Table Employee
(
EmployeeID int PRIMARY KEY identity(1,1),
Name varchar(50),
Age int,
Salary int
)
insert into Employee values('sasishekaraya',25,40000)
like this insert 2 more records
create one model name it as Employee
A model is an object that represents the data in
your application. In ASP.NET Web API, you can use strongly typed CLR objects as
models, and they will automatically be serialized to XML or JSON for the
client.
public class Employee
{
public int EmployeeID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public int Salary { get; set; }
}
The Database context class is Enity framework
object.This class contains all collections of entities that map to tables in
the database. The controller has to be access this Database context class so
that it can perform CRUD operations.
Add database context class
public class DatabaseContext:DbContext
{
public DatabaseContext()
: base("Name=DatabaseContext")
{
Database.SetInitializer<DatabaseContext>(null);
}
public DbSet<Employee> employee { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Employee>().ToTable("employee");
}
}
Install Entiry Framework From Manage NugetPackage
DbSet class is one of most important object in
Entity framework.DbSet represents collection of entities.DbSet<TEntity>
is generic version.
In web.config
<connectionStrings>
<add name="DataBaseContext" connectionString="Data Source=SQLEXPRESS;Initial
Catalog=Sample;Persist Security Info=True;User ID=sa;Password=007" providerName="System.Data.SqlClient" />
</connectionStrings>
Add a web api controller,it
handles the incoming http requests
Create a controller name it as
Employee
In Solution Explorer, right-click the the Controllers
folder. Select Add and then select Controller.
The
Employee API will expose several "read" actions as HTTP GET methods.
Each action will correspond to a method in the ProductsController class.
public class EmployeeController : ApiController
{
DatabaseContext db = new DatabaseContext();
//This method is used to get
Employee Details based on EmployeedID
public Employee GetEmp(int id)
{
var emp = db.employee.FirstOrDefault(p =>
p.EmployeeID == id);
return emp;
}
//This method is used to add
Employee to Database
[HttpPost]
public string AddEmployee(Employee emp)
{
db.employee.Add(emp);
db.SaveChanges();
return "Success";
}
Or to post employee details
to database
[HttpPost]
public HttpResponseMessage AddEmployee(Employee emp)
{
db.employee.Add(emp);
db.SaveChanges();
var response = Request.CreateResponse<Employee>(HttpStatusCode.Created,
emp);
string uri = Url.Link("DefaultApi", new { id = emp.EmployeeID });
response.Headers.Location = new Uri(uri);
return response;
}
Notice
that the method return type is now HttpResponseMessage.
By returning an HttpResponseMessage instead of
a Employee, we can control the details of the HTTP response message, including
the status code and the Location header.
//This method is used to get
list of employees
public List<Employee> GetAllEmployees()
{
var lstemps = db.employee.ToList();
return lstemps;
}
}
This
method is used to Update Employee Details
//To
update Employee Details
[HttpPut]
public string UpdateEmployee(Employee emp)
{
Employee empdetails = db.employee.Find(emp.EmployeeID);
empdetails.Age = emp.Age;
empdetails.Name = emp.Name;
empdetails.Salary =
emp.Salary;
db.SaveChanges();
return "Success";
}
This method is used to remove
Employee Details
//
To remove employee Details
public string DeleteEmployee(int id)
{
Employee empdetails = db.employee.Find(id);
db.employee.Remove(empdetails);
db.SaveChanges();
return "Success";
}
db.SaveChanges()
method is used to save the changes to the database.
Employee Controller
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using WebApiCRUD.Models;
namespace WebApiCRUD.Controllers
{
public class EmployeeController : ApiController
{
DatabaseContext db = new DatabaseContext();
public Employee GetEmp(int id)
{
var emp = db.employee.FirstOrDefault(p => p.EmployeeID ==
id);
return emp;
}
[HttpPost]
public HttpResponseMessage AddEmployee(Employee emp)
{
db.employee.Add(emp);
db.SaveChanges();
var response = Request.CreateResponse<Employee>(HttpStatusCode.Created,
emp);
string uri = Url.Link("DefaultApi", new { id = emp.EmployeeID });
response.Headers.Location = new Uri(uri);
return response;
}
public List<Employee> GetAllEmployees()
{
var lstemps = db.employee.ToList();
return lstemps;
}
//To
update Employee Details
[HttpPut]
public string UpdateEmployee(Employee emp)
{
Employee empdetails = db.employee.Find(emp.EmployeeID);
empdetails.Age = emp.Age;
empdetails.Name = emp.Name;
empdetails.Salary =
emp.Salary;
db.SaveChanges();
return "Success";
}
// To
remove employee Details
public string DeleteEmployee(int id)
{
Employee empdetails = db.employee.Find(id);
db.employee.Remove(empdetails);
db.SaveChanges();
return "Success";
}
}
}
Test api
Rightclick on project
=>manage nugget package=>search as testclient
we will get A ‘simple Test Client For Asp.Net Web
Api’ click on install
Now run the Application
Click on the GetEmployee
click on TestApi
give the id and click on send you will get the following result
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