automapper project into a larger object

问题

With Automapper, is it possible to project a smaller object onto a larger one?

For example, a controller accepts data as a ViewModel instance. I would then need to create a record in a database. So I would project this View Model onto a Domain Model. Once I have a Domain Model instance populated with View Model data I would then manually populate the additional fields in the Domain Model before storing data in the database.

Is it possible to do so?

Thanks.

回答1:

Yes this is perfectly possible. Just create a mapping from the ViewModel to the domain model and use Ignore() to ignore non-existing properties:

.ForMember(dest => dest.PropertyOnDomainModel, opt => opt.Ignore()) 

Small example:

public ActionResult Register(UserModel model)
{
    User user = Mapper.Map<User>(model);    
    user.Password = PasswordHelper.GenerateHashedPassword();
    _db.Users.Add(user);
    _db.SaveChanges();
}

With this configured mapping:

CreateMap<UserModel, User>()
    .ForMember(dest => dest.Password, opt => opt.Ignore());

This makes sure that the password won't be overridden by AutoMapper.

来源：https://stackoverflow.com/questions/19661657/automapper-project-into-a-larger-object