AutoMapper Ignore an item in a collection based on a property value in the source

Question

I'm mapping an ApplianceViewModel to a ApplianceDTO. Each Appliance has a collection of ActionViewModels which are mapped to ActionDTO. What I'd like to do is configure the mapper to ignore ActionViewModels whose IsPersisted value is False.

My ViewModel classes ...

public interface IApplianceViewModel : INotifyPropertyChanged
{
    ObservableCollection<IActionViewModel> Actions { get; set; }
    // other properties removed for simplicity
}

public interface IActionViewModel : INotifyPropertyChanged
{
    bool IsPersisted { get; set; }
    // other properties removed for simplicity
}

My DTO classes ...

public class ApplianceDTO
{
    public IEnumerable<ActionDTO> Actions { get; set; }
    // other properties removed for simplicity
}

public class ActionDTO
{
    // properties removed for simplicity
}

I set up my mapping like this ...

Mapper.CreateMap<IApplianceViewModel, ApplianceDTO>();
Mapper.CreateMap<IActionViewModel, ActionDTO>()

var appliance = new ApplianceViewModel {
    Actions = new ObservableCollection<IActionViewModel>(
        new List<IActionViewModel> {
           new ActionViewModel { IsPersisted = true },
           new ActionViewModel { IsPersisted = false }
    }};
var applianceDTO = Mapper.Map<IApplianceViewModel, ApplianceDTO>(applianceDTO);

Currently my applianceDTO will have two items in it's Actions collection, but I'd like to set up my mapping so that the ApplianceActionViewModel with the IsPersisted property set to false isn't mapped. Can I do this?

Update

Omu's comment lead me to a solution using a ValueResolver to map the collection of Actions. I'm not really happy with this solution but its the best option available.

First I created a custom ValueResolver.

public class IsPersistedCollectionResolver : ValueResolver<IApplianceViewModel, IEnumerable<ActionDTO>>
{
    protected override IEnumerable<ActionDTO> ResolveCore(IApplianceViewModel source)
    {
        return Mapper.Map<IEnumerable<IActionViewModel>, IEnumerable<ActionDTO>>(source.Actions.Where(x => x.IsPersisted));
    }
}

Then I modified my code to use it in the mapping configuration.

Mapper.CreateMap<IApplianceViewModel, ApplianceDTO>()
    .ForMember(dest => dest.Actions, opt => opt.ResolveUsing<IsPersistedCollectionResolver>());
Mapper.CreateMap<IActionViewModel, ActionDTO>();

Answer 1

have you tried doing something like :

Mapper.map(objects.Where(o => o.IsPersisted == true))