Dependency Injection Using Ninject In ASP.NET MVC
What is Dependency Injection?
In software engineering, dependency injection is a software design pattern that implements inversion of control for resolving dependencies. – Wikipedia. It makes software components are loosely coupled.
Advantages of Dependency Injection
- Flexibility to use alternative implementation of service.
- Configurable & easy to use
- Make system loosely couple
- Code becomes more reusable, testable, readable and manageable.
- Reduction of boilerplate code in the application objects
What is Ninject?
- Open Source Inversion of Control (IOC)
- It is a Dependency Injector for .NET created by Nate Kohari
- It’s very easy to use.
- Easily add from nuget.
- For more information visit Ninject.org
Let’s come to the implementation of DI using Ninject in ASP.NET MVC
Tools and Technology used
I used following tools and technology to develop the project –
- Visual Studio 2013
- Visual C#
- ASP.NET MVC 5
- Entity Framework 6
- Razor view engine
- Ninject for MVC5
Step 1: Create a ASP.net MVC Project
- From Visual studio 2013, choose File->Project
- Select MVC Template and click OK
Step 2: Create a model name Employee
Create a Model name Employee in model folder
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public string Designation { get; set; }
public string Dept { get; set; }
public string BloodGroup { get; set; }
}
Step 3: Change or Add Connection String
- Change or Add connection string in Web.config ```xml
__Step 4: Create a Context class__
* Create HRMContext Class in Repository folder.
```csharp
public class HRMContext : DbContext
{
public HRMContext()
: base("DefaultConnection")
{
}
public DbSet < Employee > Employees { get; set; }
}
Step 5: Create Repository Interface and Concrete Class
- Create IEmployeeRepository Interface and EmployeeRepository class in Repository folder
public interface IEmployeeRepository : IDisposable
{
IQueryable <Employee> All { get; }
Employee Find(int? id);
void InsertOrUpdate(Employee employee);
void Delete(int id);
void Save();
}
public class EmployeeRepository : IEmployeeRepository
{
HRMContext context;
public EmployeeRepository(HRMContext context)
{
this.context = context;
}
public IQueryable <Employee> All
{
get { return context.Employees; }
}
public Employee Find(int? id)
{
Employee objEmployee = new Employee();
objEmployee = context.Employees.Where(p => p.Id == id).FirstOrDefault();
return objEmployee;
}
public void InsertOrUpdate(Employee employee)
{
if (employee.Id == default(int))
{
// New entity
context.Employees.Add(employee);
}
else
{
// Existing entity
context.Entry(employee).State = System.Data.Entity.EntityState.Modified;
}
}
public void Delete(int id)
{
var employee = context.Employees.Find(id);
context.Employees.Remove(employee);
}
public void Save()
{
context.SaveChanges();
}
public void Dispose()
{
context.Dispose();
}
}
Step 6: Install Ninject from nuget
- In nuget package manager search and install Ninject.MVC5
Step 7: Map Interface and Concrete class in Ninject
- Go to NinjectWebCommon file in App_Start folder. Add the following line for IEmployee Interface and Employee concrete class.
public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();
/// <summary>
/// Starts the application
/// </summary>
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
/// <summary>
/// Stops the application.
/// </summary>
public static void Stop()
{
bootstrapper.ShutDown();
}
/// <summary>
/// Creates the kernel that will manage your application.
/// </summary>
/// <returns>The created kernel.</returns>
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
try
{
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
kernel.Bind<IEmployeeRepository>().To<EmployeeRepository>();
RegisterServices(kernel);
return kernel;
}
catch
{
kernel.Dispose();
throw;
}
}
/// <summary>
/// Load your modules or register your services here!
/// </summary>
/// <param name="kernel">The kernel.</param>
private static void RegisterServices(IKernel kernel)
{
}
}
Step 8: Create Controller and Views
- Click Right button on Controller Folder->Add Controller.
- Choose its name as EmployeeController.
- Now choose scaffolding template - Web API 2 Controller with actions, using Entity Framework.
- After clicking Add button, Employee Controller and Corresponding actions and views will be created automatically.
Step 9: Modify the controller
- Modify the controller - use repository instead of context directly.
public class EmployeesController : Controller
{
private readonly IEmployeeRepository repository;
public EmployeesController(IEmployeeRepository objIrepository)
{
repository = objIrepository;
}
// GET: Employees
public ActionResult Index()
{
return View(repository.All.ToList());
}
// GET: Employees/Details/5
public ActionResult Details(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = repository.Find(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// GET: Employees/Create
public ActionResult Create()
{
return View();
}
// POST: Employees/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "Id,Name,Designation,Dept,BloodGroup")] Employee employee)
{
if (ModelState.IsValid)
{
repository.InsertOrUpdate(employee);
repository.Save();
return RedirectToAction("Index");
}
return View(employee);
}
// GET: Employees/Edit/5
public ActionResult Edit(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = repository.Find(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// POST: Employees/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "Id,Name,Designation,Dept,BloodGroup")] Employee employee)
{
if (ModelState.IsValid)
{
repository.InsertOrUpdate(employee);
repository.Save();
return RedirectToAction("Index");
}
return View(employee);
}
// GET: Employees/Delete/5
public ActionResult Delete(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Employee employee = repository.Find(id);
if (employee == null)
{
return HttpNotFound();
}
return View(employee);
}
// POST: Employees/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public ActionResult DeleteConfirmed(int id)
{
repository.Delete(id);
repository.Save();
return RedirectToAction("Index");
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
repository.Dispose();
}
base.Dispose(disposing);
}
}
Step 10: Run command in Package Manager Console
- To find Package manager console go to Tool->NuGet Package Manager -> Package Manager Console
Now, run the following command one by one in Package Manager Console.
PM> Enable-Migrations -ContextTypeName HRMContext
PM> Add-Migration initialmigration
PM> Update-Database -Verbose
Step 11: Add a menu
- Add a menu name employee in _Layout.cshtml page to create a menu.
<ul class="nav navbar-nav">
<li>@Html.ActionLink("Home", "Index", "Home")</li>
<li>@Html.ActionLink("About", "About", "Home")</li>
<li>@Html.ActionLink("Contact", "Contact", "Home")</li>
<li>@Html.ActionLink("Employee", "Index", "Employees")</li>
</ul>
- Run the application and click “Employee” menu. Now you can create, delete, read update employee information.
