Update Entity for Repository Pattern and UOW Pattern C#

In one mock solution, I have created 3 mock projects to implement layered architecture design mainly the - Presentation Layer (Web) - Domain Model Layer - Infrastructure Layer. I haven't yet to add Application Service Layer (Web API).

For simplicity, I have only two domain model entities: Customer.cs and Category.cs. In my domain model layer, I also put my repository interface (both custom and generic).

In Infrastructure layer, I have the dbcontext, Unit of Work (including its interface) and repository classes (which implement repository interface).

Here is my generic repository interface

public interface IRepositoryGeneric<TEntity> where TEntity : class { // CRD void Add(TEntity entity); void Remove(TEntity entity); TEntity Get(object Id); IEnumerable<TEntity> GetAll(); void Save(); } 

Generic Repository class

public class RepositoryGeneric<T> : IRepositoryGeneric<T> where T : class { protected readonly AppDbContext db; public RepositoryGeneric(AppDbContext db) { this.db = db; } public void Add(T entity) { db.Set<T>().Add(entity); } public T Get(object Id) { return db.Set<T>().Find(Id); } public IEnumerable<T> GetAll() { return db.Set<T>().ToList(); } public void Remove(T entity) { db.Set<T>().Remove(entity); } public void Save() { db.SaveChanges(); } } 

Unit of Work Interface

public interface IUnitOfWork : IDisposable { IRepositoryCustomer Customers { get; } IRepositoryCategory Categories { get; } int Save(); } 

Unit of Work Class

public class UnitOfWork : IUnitOfWork { private readonly AppDbContext db; public UnitOfWork() { db = new AppDbContext(); } private IRepositoryCustomer _Customers; public IRepositoryCustomer Customers { get { if (this._Customers == null) { this._Customers = new RepositoryCustomer(db); } return this._Customers; } } private IRepositoryCategory _Categories; public IRepositoryCategory Categories { get { if (_Categories == null) { _Categories = new RepositoryCategory(db); } return _Categories; } } public void Dispose() { db.Dispose(); } public int Save() { return db.SaveChanges(); } } 

I learned that I should not have the update method in my generic repository interface. But without update method, I am now stuck at edit method in my presentation MVC web controller. Below, I extracted just the edit action method. The error is in that line in bold.

[HttpPost] [ValidateAntiForgeryToken] public ActionResult Edit([Bind(Include = "CategoryID,CategoryName,Description")] Category category) { if (ModelState.IsValid) { **db.Entry(category).State = EntityState.Modified;** db.Save(); return RedirectToAction("Index"); } return View(category); } 

Lastly, are my classes created in the right layer? Example should IUnitOfWork.cs be in Infrastructure layer?

My whole solution source is available at my github - https://github.com/ngaisteve1/LayeredArchitectureDesignCSharp