Dependency Injection using Ninject in ASP.NET MVC - repository pattern using Entity Framework DbContext.

---
title: Dependency Injection using Ninject in ASP.NET MVC
author: Mahedee
date: April 9, 2015
source: http://mahedee.net/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 <http://www.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...

1. Visual Studio 2013
2. Visual C#
3. ASP.NET MVC 5
4. Entity Framework 6
5. Razor view engine
6. Ninject for MVC5

## Step 1: Create a ASP.net MVC Project

-   From Visual studio 2013, choose **File** -> **Project** -> **ASP.NET Web Application**.
    -   Select the **MVC** template and click **OK**.

## Step 2: Create a model name Employee

Create a Model name Employee in model folder.

```cs
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 a connection string to your `Web.config` file.

```xml
<connectionStrings>
   <add name="DefaultConnection" connectionString="Data Source=localhost;Initial Catalog=HRMDB;User ID=sa; Password=leads@123" providerName="System.Data.SqlClient" />
</connectionStrings>
```

## Step 4: Create a Context class

Create `HRMContext.cs` class file in **Repository** folder.

```cs
public class HRMContext : DbContext
{
    public HRMContext() : base("DefaultConnection")
    { }

    public DbSet < Employee > Employees { get; set; }
}
```

## Step 5: Create Repository Interface and Concrete

Create `IEmployeeRepository` Interface and `EmployeeRepository` classes in a
folder named **Repository**.

```cs
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 MVC5 from Nuget

Install `Ninject.MVC5` from [Nuget](https://www.nuget.org/) package manager.

## Step 7: Map Interface and Concrete class in Ninject

Open the `NinjectWebCommon.cs` file located in the **App_Start** folder. Add the
following line for the `IEmployee` interface and `Employee` concrete class.

```cs
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.
    private static void RegisterServices(IKernel kernel)
    {
    }
}
```

## Step 8: Create Controller and Views

Right-click on the **Controller** folder, and choose **Add Controller**. Name
the controller `EmployeeController`. Now choose the **Scaffolding** template for
the controller, and "Web API 2 Controller with actions, using Entity Framework".

After clicking the **Add** button, **Employee** controller and corresponding
actions and views will be created automatically.

## Step 9: Modify the controller

Modify the controller -- use `IEmployeeRepository` instead of DbContext directly.

```cs
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);
        }

        var 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 over-posting 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);
        }

        var 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);
        }

        var 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: Enable Entity Framework Database Migrations

To find Package manager console go to:

-   **Tools** -> **NuGet Package Manager** -> **Package Manager Console**

Now, build the application and run the following commands from the Package
Manager Console.

```powershell
PM> Enable-Migrations -ContextTypeName HRMContext
PM> Add-Migration initialmigration
PM> Update-Database -Verbose
```

## Step 11: Add a menu

Add a menu named employee in `_Layout.cshtml` page to create a menu.

```html
<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.

## Download the Source Code

-   [Download Source Code](http://mahedee.net/?wpdmact=process&did=NjAuaG90bGluaw==)