Microsoft Unity in ASP.NET MVC

Introduction

One way for decoupling classes is using Unity. You can learn more about Unity here. In this article, I will try to describe the usage of Unity. For doing that, you should follow the steps below.

Using Code

1. Create a new project in Visual Studio (Visual Studio 2012 recommended)
   1. In File menu, click New -> Project.
   2. In New Project window, select Visual C# -> Web and then select ASP.NET MVC 4 Web Application. Figure a-1.
   3. Name the project (e.g. TestUnity).
   4. Click OK button.
   5. In New ASP.NET MVC 4 Project window, select Internet Application and Razor View engine (creating unit test project is optional ). Figure a-2.
   6. Click OK button.



Figure a-1: Create a new project in Microsoft Visual Studio 2012.



Figure a-2: Select Internet Application and Razor view engine.

After step A, your project has been created and is ready for programming. Now you should install Unity as below (step B).

2. Installing Microsoft Unity
   1. In solution explorer window, right click on References folder.
   2. Click Manage NuGet Packages (don’t forget you have to connect to the internet).
   3. In left panel of Manage NuGet Packages window, select Online.
   4. In Search box placed in right panel of Manage NuGet Packages window, type unity3.
   5. In list of search result, select Unity bootstrapper for ASP.NET MVC and click install (click Accept button if it wants). After some moments, Unity will be installing. Figure b-1.
   6. Click close button to close Manage NuGet Packages window.



Figure b-1: Install Unity bootstrapper for ASP.NET MVC.

Unity will add two classes into App_Start folder (UnityConfig.cs, UnityMvcActivator.cs).

3. Create a class in Models folder named Person as follows:
   1. Right click on Models folder and select Add -> Class
   2. Name the class Person.cs
   3. Type the below code into Person class:

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

        using System.Data.Entity;
        using System.ComponentModel.DataAnnotations;

        namespace TestUnity.Models
        {
            public class Person
            {
                [ScaffoldColumn(false)]
                public int Id { get; set; }

                [Required]
                public string Name { get; set; }

                public int Age { get; set; }

                [Display(Name = "Contact Information")]
                public string ContactInfo { get; set; }
            }
        }    

4. Create WSCDBProvider class into Models folder as follows:
   1. Right click on Models folder and select Add->Class
   2. Name the class WSCDBProvider.cs
   3. Type the following code into WSCDBProvider.cs class

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

        using System.Data.Entity;

        namespace TestUnity.Models
        {
            public class WSCDBProvider : DbContext
            {
                public DbSet<person> Persons { get; set; }
            }
        }    

5. Create an interface in Models folder named IPersonRepository:
   1. Right click on Models folder and select Add -> Class
   2. In items list, select Interface and named it IPersonRepository.cs
   3. Click Add button
   4. Type the following code into IPersonRepository interface:

        using System;
        using System.Collections.Generic;
        using System.Linq;
        using System.Text;
        using System.Threading.Tasks;

        using TestUnity.Models;

        namespace TestUnity.Models
        {
            public interface IPersonRepository : IDisposable
            {
                IEnumerable<person> GetAll();
                void InsertorUpdate(Person contact);
                Person Find(int id);
                bool Delete(int id);
                void Save();
            }
        }   

6. Create a class in Models folder named PersonRepository as follows:
   1. Right click on Models folder and select Add -> Class
   2. Name the class PersonRepository.cs
   3. Type the following code into class:

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

        using System.Data;

        namespace TestUnity.Models
        {
            public class PersonRepository : IPersonRepository
            {
                private WSCDBProvider db = new WSCDBProvider();

                public IEnumerable<person> GetAll()
                {
                    return db.Persons.ToList();
                }

                public Person Find(int id)
                {
                    return db.Persons.Find(id);
                }

                public bool Delete(int id)
                {
                    try
                    {
                        Person person = Find(id);
                        db.Persons.Remove(person);
                        Save();
                        return true;
                    }
                    catch (Exception)
                    {
                        return false;
                    }
                }

                public void InsertorUpdate(Person person)
                {
                    if (person.Id == default(int))
                    {
                        // New entity
                        db.Persons.Add(person);
                    }
                    else
                    {
                        // Existing entity
                        db.Entry(person).State = EntityState.Modified;
                    }
                }

                public void Save()
                {
                    db.SaveChanges();
                }

                public void Dispose()
                {
                    db.Dispose();
                }

            }
        } 

7. Creating Person Controller:
   1. Right click on Controller folder and select Add -> Controller
   2. In Add Controller window, name controller PersonController
   3. For Scaffolding options, select MVC controller with empty read/write actions
   4. Click Add button. Figure g-1.
   5. Change the controller code as shown below:



Figure g-1 : Add Controller

        using System;
        using System.Collections.Generic;
        using System.Linq;
        using System.Web;
        using System.Web.Mvc;

        using TestUnity.Models;

        namespace TestUnity.Controllers
        {
            public class PersonController : Controller
            {
                private readonly IPersonRepository repository;

                public PersonController(IPersonRepository repository)
                {
                    this.repository = repository; 
                }

                public ActionResult Index()
                {
                    var persons = repository.GetAll();
                    return View(persons);
                }

                public ActionResult Details(int id)
                {
                    var person = repository.Find(id);
                    return View(person);
                }

                public ActionResult Create()
                {
                    return View();
                }

                [HttpPost]
                public ActionResult Create(Person person)
                {
                    try
                    {
                        repository.InsertorUpdate(person);
                        repository.Save();
                        return RedirectToAction("Index");
                    }
                    catch
                    {
                        return View();
                    }
                }

                public ActionResult Edit(int id)
                {
                    var person = repository.Find(id);
                    return View(person);
                }

                [HttpPost]
                public ActionResult Edit(int id, Person model)
                {
                    try
                    {
                        var person = repository.Find(id);
                        repository.InsertorUpdate(person);
                        repository.Save();
                        return RedirectToAction("Index");
                    }
                    catch
                    {
                        return View();
                    }
                }

                public ActionResult Delete(int id)
                {
                    var person = repository.Find(id);
                    return View(person);
                }

                [HttpPost, ActionName("Delete")]
                public ActionResult DeleteConfirmed(int id)
                {
                    bool ret = repository.Delete(id);
                    if(ret)
                        return RedirectToAction("Index");
                    return View();
                }
        
                protected override void Dispose(bool disposing)
                {
                    if (disposing)
                    {
                        repository.Dispose();
                    }
                    base.Dispose(disposing);
                }
            }
        }    

8. Now you should use Unity for injecting repository into Controller.
   1. Open UnityConfig.cs class from App_Start folder
   2. Type injecting command in RegisterTypes method as shown below:

    container.RegisterType<IPersonRepository, PersonRepository>();



Figure h-1 : UnityConfig.cs class
9. Now your project is ready for creating Views and Run and Use.