Mapping from ViewModel to DTo to Domain using automapper - asp.net-mvc-3

Question

I'm having a trouble do the following mapping:
Domain (simplified version):
public class Ad
{
// Primary properties
public int Kms { get; set; }
// Navigation properties
public virtual Model Model { get; set; }
}
DTO:
public class CreateAdDto
{
// Primary properties
public int Kms { get; set; }
// Navigation properties
public virtual ModelDto Model { get; set; }
}
ViewModel:
public class CreateAdViewModel
{
// Primary properties
public int Kms { get; set; }
public int Make_Id { get; set; }
public int Model_Id { get; set; }
// Navigation properties
public IEnumerable<SelectListItem> MakeList { get; set; }
public IEnumerable<SelectListItem> ModelList { get; set; }
}
In the Controller, when I do the Mapping I'm loosing the Make_ID from the Dropdownlist of the View:
public virtual ActionResult Create(CreateAdViewModel adViewModel)
{
if (ModelState.IsValid)
{
var adDto = Mapper.Map<CreateAdViewModel, CreateAdDto>(adViewModel);
_adService.CreateAd(adDto);
}
return RedirectToAction(MVC.Home.Index());
}
The mapping is:
Mapper.CreateMap<CreateAdViewModel, CreateAdDto>()
Thanks.

Answer 1

As you have mentionned, the Ad need to know the Model_Id and to set it into the Model
Mapper.CreateMap<CreateAdDto, Ad>()
.ForMember(dest => dest.Model, opt => opt.MapFrom(src => new Model { Id = src.Model_Id }));
You also need from the other mapping side to let the Dto know where to get the Model id.
Mapper.CreateMap<Ad, CreateAdDto>()
.ForMember(dest => dest.Model_Id, opt => opt.MapFrom(src => src.Model.Id}));
The code above is not secure because a validation to see if Model is null should be added.
For the rest of your code, you seem to do it right. The section with Entity Framework requires you to attach because the entity Model already exist, otherwise, EF would insert this entity to the database.

Answer 2

CreateAdDto doesn't have a Make navigation property or a Make_Id property.

Answer 3

Solution found after some research:
ViewDomain:
public class CreateAdViewModel
{
// Primary properties
public int Kms { get; set; }
public int Make_Id { get; set; }
public int Model_Id { get; set; }
// Navigation properties
public IEnumerable<SelectListItem> MakeList { get; set; }
public IEnumerable<SelectListItem> ModelList { get; set; }
}
DTO:
public class CreateAdDto
{
// Primary properties
public int Kms { get; set; }
public int Model_Id { get; set; }
// Navigation properties
//public virtual ModelDto Model { get; set; }
}
Domain:
public class Ad
{
// Primary properties
public int Kms { get; set; }
// Navigation properties
public virtual Model Model { get; set; }
}
Viewmodel -> Dto Mapping:
Mapper.CreateMap<CreateAdViewModel, CreateAdDto>();
Dto -> Domain Mapping:
Mapper.CreateMap<CreateAdDto, Ad>()
.ForMember(dest => dest.Model, opt => opt.MapFrom(src => new Model { Id = src.Model_Id }));
Atention:
To achieve this with Entity Framework, I had to attach first the Model Entity to the Context and then Ad the new Ad:
public void CreateAd(CreateAdDto adDto)
{
var adDomain = Mapper.Map<CreateAdDto, Ad>(adDto);
_modelRepository.Attach(adDomain.Model);
_adRepository.Add(adDomain);
_adRepository.Save();
}
Hope this is the best practice.
BTW I would like to have some opinions regarding this aproach.
Thanks.

Answer 4

Based on what is I see in your question, I suggest a simple approach. Your application is medium scale. You should very carefully about maintainability,my experience say.So try to create a simple an strain forward approach for yourself like below approach:
I can describe all layer in detail but with notice to title of your question I prefer describe only Model(bussiness Ojbect) layer:
Good! As you can see PM.Model include:
Tow sub folders contain our ViewModels and in root of Library we have a .tt file contain Entity framework Objects (POCO classes) and we have a Mapper folder(Since that i dont like use autoMapper or third party like this :) ).
You can see IListBox interface in Domain layer. I put all ListBox container to this interface.
I hope current approach useful for you but finally I suggest remove one of this layers DTO or ViewModel, because in the future will be very complex.
Good luck

Answer 5

Do you aware about cost of these mapping?! You have 2 layers mapping (before arrived to Entity framework) for an simple insert.We can do more complex CRUD(s) in less than 2 layers mapping.
How to think about maintainability of this code?
Please keep DRY,KISS,SOLID conventions in your mind and top of your everyday work.
Good luck