Learning MVC – Part 5:Repository Pattern in MVC3 Application with Entity Framework

Introduction

Our Roadmap

Pre-requisites

1. We have running sample application that we created in the third part of the article series.
2. We have EntityFramework 4.1 package or DLL on our local file system.
3. We understand how the MVC application is created.

Repository Pattern

• It centralizes the data logic or Web service access logic.
• It provides a substitution point for the unit tests.
• It provides a flexible architecture that can be adapted as the overall design of the application evolves.

Creating Repository

using System;
using System.Collections.Generic;

namespace LearningMVC.Repository
{
public interface IUserRepository:IDisposable
{
IEnumerable GetUsers();
User GetUserByID(int userId);
void InsertUser(User user);
void DeleteUser(int userId);
void UpdateUser(User user);
void Save();
}
}

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;

namespace LearningMVC.Repository
{
public class UserRepository:IUserRepository
{
private MVCEntities context;

public UserRepository(MVCEntities context)
{
this.context = context;
}

public IEnumerable GetUsers()
{
return context.Users.ToList();
}

public User GetUserByID(int userId)
{
return context.Users.Find(userId);
}

public void InsertUser(User user)
{
context.Users.Add(user);
}

public void DeleteUser(int userId)
{
User user = context.Users.Find(userId);
context.Users.Remove(user);
}

public void UpdateUser(User user)
{
context.Entry(user).State = EntityState.Modified;
}

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);
}
}
}

Interface

Class

#region Private member variables...
private IUserRepository userRepository; 
#endregion

#region Public Constructor…
/// <summary>
/// Public Controller to initialize User Repository
/// </summary>
public MyController()
{
this.userRepository = new UserRepository(new MVCEntities());
}
#endregion

var userList = from user in userRepository.GetUsers() select user;
            var users = new List();
            if (userList.Any())
            {
                foreach (var user in userList)
                {
                    users.Add(new LearningMVC.Models.UserList() 
                    { UserId = user.UserId, Address = user.Address, 
                    Company = user.Company, FirstName = user.FirstName, 
                    LastName = user.LastName, Designation = user.Designation, 
                    EMail = user.EMail, PhoneNo = user.PhoneNo });
                }
            }

Details

Create

Edit

Delete

Conclusion

• You want to maximize the amount of code that can be tested with automation and to isolate the data layer to support unit testing.
• You access the data source from many locations and want to apply centrally managed, consistent access rules and logic.
• You want to implement and centralize a caching strategy for the data source.
• You want to improve the code’s maintainability and readability by separating business logic from data or service access logic.
• You want to use business entities that are strongly typed so that you can identify problems at compile time instead of at run time.
• You want to associate a behavior with the related data. For example, you want to calculate fields or enforce complex relationships or business rules between the data elements within an entity.
• You want to apply a domain model to simplify complex business logic.