Question

I have a ViewModel that looks like this:

public class CreateReviewViewModel
{
   public string Title { get; set; }
   public decimal Score { get; set; }
   public ICollection<RecommendationViewModel> Recommendations { get; set; }
}

So, the first two are basic native types – easy.

The third property is a collection of another ViewModel:

public class RecommendationViewModel
{
   public RecommendationType RecommendationType { get; set; }
   public bool IsRecommendedFor { get; set; }
}

RecommendationType is an enum in my domain model, which has byte values representing a different “recommendation”.

On my [HttpGet] action, i do this:

var model = new CreateReviewViewModel
{
   Recommendations = SomeMethodWhichLoopsThroughTheEnumMembersAndCreatesTheModel();
}
return View(model);

So i end up with a list of RecommendationViewModel, with the bool properties set to false.

Then on my View, i use EditorTemplates:

@Html.EditorFor(model => model.Recommendations)

Which calls a custom Editor template that renders a label and checkbox for the two properties. Cool.

So – there’s the background, which hopefully makes sense.

How do i map that ViewModel to a Review domain model in the [HttpPost] action?

The part of the Review object looks like this:

public class Review
{
   public bool IsRecommendedForA { get; set; }
   public bool IsRecommendedForB { get; set; }
   // etc
}

I’m currently doing custom mapping like this:

var review = new Review();
review.IsRecommendedForA = this.Recommendations.SingleOrDefault(x => x.RecommendationType == RecommendationType.A).IsRecommendedFor;
review.IsRecommendedForB = this.Recommendations.SingleOrDefault(x => x.RecommendationType == RecommendationType.B).IsRecommendedFor;

Which is very tedious.

Can i do the above with AutoMapper?

Of course, i could just add all the different RecommendationType’s as basic properties on the ViewModel instead of a collection, but then my View’s become complicated, and i can’t use EditorTemplates to implicitly loop through the collection – i would have to write out Html.EditorFor for each property.

Any ideas?

Answer 1

I have one possible solution:

Mapper.CreateMap<CreateReviewViewModel, Review>()
   .ForMember(dest => dest.IsRecommendedForA, opt => opt.MapFrom(src => src.IsRecommendedFor(RecommendationType.A)))
   .ForMember(dest => dest.IsRecommendedForB, opt => opt.MapFrom(src => src.IsRecommendedFor(RecommendationType.B)));

Where IsRecommendedFor is a hook property, using the LINQ expression stated earlier in my question to work out if the model contains the property, and it’s checked.

Which is better than the manual left-to-right, but still not great.

I’ve taken a look at custom converters/resolvers, but none take additional parameters (e.g resolve from this to this, using this parameter also), so i can’t see how i can use them.

I’ll go with this for now, but hoping someone knows how to do it better.