Linq to Sql DB Object Oriented Object Mapping and Performance

Question

I had a problem trying to execute my LINQ to SQL queries and map to my DRY domain objects without resorting to the cost of a few hits in db. In this example:

var query1 = from x in db.DBProducts
            select new MyProduct
            {
                Id = x.ProductId,
                Name = x.ProductName,
                Details = new MyProductDetail
                {
                    Id = x.DBProductDetail.ProductDetailId,
                    Description = x.DBProductDetail.ProductDetailDescription
                }
            }

The request will make ONE round trip in the database. Big! However, the problem that I see in this is that in the end I will also have a GetProductDetails method, which will also have to execute some of the SAME objects "object object → domain object", very similar to what indicated above.

To facilitate some of the comparisons, I thought it would be a cool idea to extend the partial data object classes to make a comparison for me:

public partial class DBProduct
{
    MyProduct ToDomainObject()
    {
        return new MyProduct
        {
            Id = this.ProductId,
            Name = this.ProductName,
            Details = this.DBProductDetails.ToDomainObject()
        };
    }
}

public partial class DBProductDetail
{
    MyProductDetail ToDomainObject()
    {
        return new MyProductDetail
        {
            Id = this.ProductDetailId,
            Description = this.ProductDetailDescription
        };
    }
}

Nice! Now I can simply rewrite query1 as follows:

var query1 = from x in db.DBProducts
            select x.ToDomainObject();

. , , , ToDomainObject() . , . Profiler db ONCE, . , , . , : LINQ to SQL, DRY ( )?

Answer 1

AutoMapper. , - :

new MyProduct
{
    Id = x.ProductId,
    Name = x.ProductName,
    Details = new MyProductDetail
    {
        Id = x.DBProductDetail.ProductDetailId,
        Description = x.DBProductDetail.ProductDetailDescription
    }
}