实体框架映射到域对象

Question

I have a rich domain, so I want to separate the domain model from the persistence model, which is recommended from all Domain Driven Design practitioners. Suppose i have a following rich domain model:

public class Order
{
    Public Guid Id {get; private set;}
    Public Property1 {get; private set;}
    Public Property2 {get; private set;}

    private List<Item>  Items;
    Public AddItem() { }
    ....
}

This is my Data Transfer Obect (Entity Framework is using it):

public class OrderDTO 
{
    public Guid Id {get; set;}
    Public Property1 {get; set;}
    Public Property2 {get; set;}
    ...
}

Entity Framework DbContext:

public partial class EntityFrameworkContext : DbContext
{
    ...
    public virtual DbSet<OrderDTO> Orders{ get; set; }
    ...
}

Repository:

public class OrderRepository : IOrderRepository 
{
    private EntityFrameworkContext _context;
    ....
    public IQueryable<Order> FindBy(Expression<Func<Order, bool>> predicate)
    {
        //how to implement this ??
    }
}

How can i implement the Method FindBy ?? I cannot use _context.Orders.where(predicate) because entitiy framwork context works with OrderDTO and not with Order. I need somehow a mapping between Func<Order, bool> to Func<OrderDTO, bool> .

Any help would be appriciated.

Answer 1

What if you use OrderDTO to build the predicate expression

public class OrderRepository : IOrderRepository 
{
    private EntityFrameworkContext _context;
    ....
    public IQueryable<Order> FindBy(Expression<Func<OrderDTO, bool>> predicate)
    {
        return ConvertToDomainModel(_context.Orders.where(predicate);
    }
}