CODEWITHSUNDEEP
c#automapper
Adam
Adam

Reputation: 4227

AutoMapper - how to utilise the collection index in a mapping

I would like to map a Dto to an Entity, and store the array index of the Dto into a property on the Entity.

e.g (pseudo):

class Dto {}

class Entity{ int Index; }

// perform mapping from collection of Dto, to collection of Entity
Map<Entity>(new Dto[]{ new Dto(), new Dto(), new Dto() };

// maps to
Entity[]{
  Entity{ Index = 0 },
  Entity{ Index = 1 },
  Entity{ Index = 2 }
}

Sure I can do this manually, however, I already have AutoMapper in my architecture, so it makes sense to configure a mapping for it.

I cannot find a way to do this. I found this thread: https://github.com/AutoMapper/AutoMapper/issues/1238

Which alludes to using a resolver, however, resolvers no longer have access to the resolution hierarchy/stack. I believe this may have been changed for performance reasons, since the comment above was written.

It seems to me, I should be able to easily get access to the 'root' source object (the object/collection passed in to the Map<>(source) method - and having such access would make it trivial to solve this - but I cannot find it.

Any pointers?

Thanks,

Upvotes: 3

Views: 906

Answers (1)

Boris Lipschitz
Boris Lipschitz

Reputation: 9516

Here is how you could achieve it using AfterMap:

Mapper.CreateMap<SourceDto, Destination>()
    .AfterMap((_, dest) => 
    {
        int id = 0;
        foreach (var entity in dest.Entities)
        {
            entity.Index = id++;
        }
    });

Upvotes: 1

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