Repository pattern by using entity framework

Question

Following is my code. I want to know it is true or not.

public interface IRepository<T> : IDisposable
{
    IQueryable<T> GetAll();
    T Update(T entity);
    T Insert(T entity);
    T GetById(T entity);
    void Delete(T entity);
    void Save();
}

public class Repository<T> : IRepository<T> where T : class
{
    private readonly SchoolDBEntities _context;

    public Repository(SchoolDBEntities context)
    {
        _context = context;
    }

    public IQueryable<T> GetAll()
    {
        return _context.Set<T>();
    }

    public T Update(T entity)
    {
        var result = _context.Set<T>().Attach(entity);
        _context.Entry(entity).State = EntityState.Modified;
        return result;
    }

    public T Insert(T entity)
    {
        return _context.Set<T>().Add(entity);
    }

    public T GetById(T entity)
    {
        return _context.Set<T>().Find(entity);
    }

    public void Delete(T entity)
    {
        _context.Set<T>().Remove(entity);
    }

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

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

The problem is, I don't know when and where to call the Save and Dispose methods.

Answer 1

Don't do dispose in IRepository<T>

Try UnitOfWork pattern like this

public interface IUnitOfWork : IDisposable
{
    IRepository<Cart> CartRepository { get; }
    IRepository<Product> ProductRepository { get; }
    void Save();
}

public class UnitOfWork : IUnitOfWork
{
    readonly SqlDbContext _context;
    public UnitOfWork()
    {
        _context = new SqlDbContext();
    }

    private bool _disposed;
    protected virtual void Dispose(bool disposing)
    {
        if (!_disposed)
        {
            if (disposing)
            {
                _context.Dispose();
            }
        }
        _disposed = true;
    }
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

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

    public IGenericRepository<Cart> CartRepository
    {
        get { return new Repository<Cart>(_context); }
    }

    public IGenericRepository<User> UserRepository
    {
        get { return new Repository<User>(_context); }
    }
}

You can call it like this

using (_unitOfWork) 
{ 
   var p = _unitOfWork.ProductRepository.SingleOrDefault(p => p.Id == productId); 
   _cartRepository.Add(p);
   _unitOfWork.Save(); 
}