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What does Repository mean?
Dictionary meaning: A place where things may be put for safekeeping.
Repository Pattern:
The Repository Pattern allows to centralise all data access logic in one place. It is a common construct to avoid duplication of data access logic throughout our application. The Repository pattern adds a separation layer between the data and business layers of an application.
Generic Repository Pattern:
A generic(relating to) repository is often used with the ORM(entity framework) to speed up the process of creating a data layer.With generic feature, we can reduce the amount of code we need for common scenarios.
namespace WebApplication1.Repository
{
interface IRepository : IDisposable where T : class
{
IEnumerable GetAll();
T GetById(object Id);
void Insert(T model);
void Update(T model);
void Delete(object id);
void Save();
}
}
Explanation:
interface IRepository
Show an interface of a generic repository of type T, which is a LINQ to SQL entity. It provides a basic interface with operations like Insert, Update, Delete, GetById and GetAll.
IDisposable
The IDisposable Interface, Provides a mechanism for releasing unmanaged resources.
where T : class
where T : class
This is constraining the generic parameter to a class.
The type argument must be a reference type; this applies also to any class, interface, delegate, or array type.
namespace WebApplication1.Repository
{
public class GenericRepository : IRepository where T : class
{
Customer_Entities context = null;
private DbSet entities = null;
public GenericRepository(Customer_Entities context)
{
this.context = context;
entities = context.Set();
}
public IEnumerable GetAll()
{
return this.entities.ToList();
}
public T GetById(object id)
{
return this.entities.Find(id);
}
public void Insert(T model)
{
context.Entry(model).State = EntityState.Added;
}
public void Update(T model)
{
context.Entry(model).State = EntityState.Modified;
}
public void Delete(object id)
{
T existing = this.entities.Find(id);
this.entities.Remove(existing);
}
public void Save()
{
context.SaveChanges();
}
private bool disposed = false;
protected virtual void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
context.Dispose();
}
}
this.disposed = true;
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
}
}
Use of Generic Repository in MVC-Application:
namespace WebApplication1.Controllers
{
public class HomeController : Controller
{
private GenericRepository CustRepository;
public HomeController()
{
this.CustRepository = new GenericRepository(new Customer_Entities());
}
// GET: Home
public ActionResult Index()
{
var test = CustRepository.GetAll();
return View(test);
}
// GET: Insert
public ActionResult Insert()
{
return View();
}
[HttpPost]
public ActionResult Insert(Customer model)
{
if (ModelState.IsValid)
{
CustRepository.Insert(model);
CustRepository.Save();
}
return RedirectToAction("Index");
}
// GET: Delete
public ActionResult Delete(int id)
{
this.CustRepository.Delete(id);
CustRepository.Save();
return RedirectToAction("Index");
}
// GET: Update
public ActionResult Update(int id)
{
return View(this.CustRepository.GetById(id));
}
[HttpPost]
public ActionResult Update(Customer model)
{
this.CustRepository.Update(model);
CustRepository.Save();
return RedirectToAction("Index");
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
}
}
}
Explanation:
private GenericRepositoryCustRepository;
Declaration of GenericRepository reference.
public HomeController()
{
this.CustRepository = new GenericRepository(new Customer_Entities());
}
In the constructor we initialize the object with GenericRepository class, passing Customer_Entities objct to the constructor as parameter
Hope this will help 🙂
says:
Wonderful explanation on the topic. Keep sharing more articles.
vikash Kumar Mishra says:
but sir if i want to add the Business layer,Data access layer,repository layer with Ado.net entity frame work then how i can do that
Shashangka Shekhar says:
We then separate those classes by creating class libraries then reference it.
Carlos Encarnacion says:
thank you very much, helped me understand.
Shashangka Shekhar says:
You are most welcome, glad that it helps you 🙂
Jess Rubio says:
what if am going to retrieve result if combination of two table. like in LINQ we use join/inner join how could i retrieve it. and modified it?do i have to create another model for the result of two or more table?
Shashangka Shekhar says:
Use dynamic feature in C# 4.0. get more details :
says:
Awesomely written article. Need and clean. Very precious about the topic.