Distract DAL from Entity Framework Implementation

Question

First of all, I'm sorry if this is a long post, but I do not know how to correctly explain the problem without the necessary details.

I'm having trouble finding a way to abstract my DAL from an Entity Framework implementation. The project I'm working on is very small, but if in the future I want to switch to another ORM, for example, NHibernate or just ADO.NET, I would like to write code only for implementation, and not for the whole DAL.

Say I have these entities in MyWallet.DAL:

public interface IWallet {
    long Id { get; set; }
    float TotalAmountOfMoney { get; set; }
    long CurrencyId { get; set; }
    ICurrency Currency { get; set; }
    DateTime RecordedOn { get; set; }
    ICollection<IMoneyMovement> MoneyMovements { get; set; }
}

public interface ICurrency {
    long Id { get; set; }
    char Symbol { get; set; }
    string Code { get; set; }
    string Description { get; set; }
}

public interface IMoneyMovement {
    long Id { get; set; }
    float Amount { get; set; }
    string Description { get; set; }
    long WalletId { get; set; }
    IWallet Wallet { get; set; }
    DateTime RecordedOn { get; set; }
    DateTime MovedOn { get; set; }
}

, , , Entity Framework (, MyWallet.DAL.EntityFramework). , Entity Framework [Key] [ForeignKey] .

MyWallet.DAL, IWalletRepository, IMoneyMovementRepository, ICurrencyRepository, . , . , , .

- , DAL -, :

public class WalletService {
    private readonly IWalletRepository _walletRepository;
    private readonly IWalletFactory _walletFactory;

    public WalletService(IWalletRepository walletRepository, 
        IWalletFactory walletFactory) {

        _walletRepository = walletRepository;
        _walletFactory = walletFactory;
    }

    public CreatedWallet CreateWallet(CreateWalletRequest request) {
        var wallet = _walletFactory.Create();

        wallet.CurrencyId = request.CurrencyId;
        wallet.TotalAmountOfMoney = request.TotalAmountOfMoney;
        wallet.RecordedOn = DateTime.Now;

        _walletRepository.Create(wallet);
        _walletRepository.SaveChanges();

        return new CreatedWallet {
            Id = wallet.Id
        }
    }
}

, , - , , DataContext, SaveChanges , .

, Entity Framework:

public class EFDataContext : DbContext {
    public EFDataContext() : base ("name=MyConnectionString") {
    }

    public virtual DbSet<EFWallet> Wallets { get; set; }
    public virtual DbSet<EFMoneyMovement> MoneyMovements { get; set; }
    public virtual DbSet<EFCurrency> Currencies { get; set; }
}

public class EFWalletRepository : IWalletRepository {
    private readonly EFDbContext _dataContext;

    public EFWalletRepository(EFDbContext dataContext) {
        _dataContext = dataContext ?? new EFDbContext();
    }

    public int SaveChanges() {
        return _dataContext.SaveChanges();
    }

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

    public void Create(IWallet wallet) {
        ...???
    }
}

, : , DataContext ? ?

UPDATE:

, , @TomTom, Entity Framework, ? , EF . , EF DAL, - .

@tdragon / : , , DbContext :

public class EFWalletRepository : IWalletRepository {
    private readonly EFDbContext _dataContext;

    public EFWalletRepository() {
        _dataContext = new EFDbContext();
    }

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

    public IEnumerable<Wallet> Wallets {
        get { return _dataContext.Wallets; }
    }

    public void SaveWallet(Wallet wallet) {
        if (wallet.Id == 0) {
            _dataContext.Wallets.Add(wallet);
        } else {
            var databaseEntry = _dataContext.Wallets.Find(wallet.Id);
            //update properties
        }

        _dataContext.SaveChanges();
    }
}

Answer 1

: , . ( ) "-". EF .

, . ? "" ( ). , ORM, - -? , .

Answer 2

(). , ?

, , :

public class EFWalletRepository : IWalletRepository<EFWallet>
{
    public void Create(EFWallet wallet)
    {
        _dataContext.Add(wallet);
    }
}

:

• . - , .
• , SaveChanges() - " " .
• , , DbContext, " ".