automapper create.map（）到集合属性

Question

How do you map to a collection of property but only interested with the last record of the collection.

Say, something like.

public class ItemDTO <-- destination class
{
  public string Name { get; set; }
  public decimal PricesPrice { get; set; }
}

public class Item <-- Source class
{
  public int Id { get; set; }
  public string Name { get; set; }

  public virtual ICollection<Price> Prices { get; set; }
}

public class Price <-- Source class
{
  public int Id { get; set; }
  public int ItemId { get; set; }
  public decimal Price { get; set; }

  public virtual Item Item { get; set; }
}

Then I have tried something like this, but doesn't seems to be right.

Mapper.CreateMap<Item, ItemDTO>()
                .ForMember(dto => dto.PricesPrice, opt => opt.MapFrom(s => s.Prices.LastOrDefault().Price));

EDIT: And then after that I did a Projection because If I use Mapper.Map() It will return the entire result set which is not what I want, I only want the values I needed. So I did something like this:

Project().To<ItemDTO>()

Well, basically, I want something like this:

from item in SomeDbContext.Items
where item.ItemId == 1
select new ItemDTO
{
  Name = item.Name,
  PricesPrice = item.Prices.LastOrDefault()
}

Can above code be done using AutoMapper ?

Answer 1

I think I understand what you are trying to do now.

Try this

from item in SomeDbContext.Items
where item.ItemId == 1
select Mapper.Map<ItemDTO>(item)

or you could use LINQ

SomeDbContext.Items.Where(i=> i.ItemId == 1).Select(Mapper.Map<ItemDTO>)

Both of these will return you a list of ItemDTO object where the ItemId is 1