Automapper failing to map on IEnumerable

Question

I have two classes like so:

public class SentEmailAttachment : ISentEmailAttachment
{
    public SentEmailAttachment();

    public string FileName { get; set; }
    public string ID { get; set; }
    public string SentEmailID { get; set; }
    public string StorageService { get; set; }
    public string StorageServiceFileID { get; set; }
}

And

public class SentEmailAttachmentItem : ISentEmailAttachment
{
    [ItemName]
    public string ID { get; set; }
    public string SentEmailID { get; set; }
    public string FileName { get; set; }
    public string StorageService { get; set; }
    public string StorageServiceFileID { get; set; }
}

Identical, as you can see (they both implement interface to ensure this)

I then have the following mapping:

Mapper.CreateMap<IEnumerable<SentEmailAttachmentItem>, IEnumerable<SentEmailAttachment>>();
Mapper.CreateMap<IEnumerable<SentEmailAttachment>, IEnumerable<SentEmailAttachmentItem>>();

I then have the following Unit test:

//create a load of sent email attachments
var listOfSentEmailAttachments = new List<SentEmailAttachment>();

for (int i = 0; i < 10; i++)
    listOfSentEmailAttachments.Add(new SentEmailAttachment { FileName = "testFileName", ID = Guid.NewGuid().ToString(), SentEmailID = Guid.NewGuid().ToString(), StorageService = "S3", StorageServiceFileID = "SomeFileID" });

var sentEmailAttachmentItems = Mapper.DynamicMap<IEnumerable<SentEmailAttachment>, IEnumerable<SentEmailAttachmentItem>>(listOfSentEmailAttachments);

var itemToTest = sentEmailAttachmentItems.First();

Assert.IsInstanceOfType(itemToTest, typeof(SentEmailAttachmentItem));

This fails - The IEnumerable sentEmailAttachmentItems is empty. It didn't map the list of SentEmailAttachments to it...

Any idea what's going on??

I have it working on single objects (mapping one of each to one of each) but not a collection...

Answer 1

You do not need to explicitly map collection types, only the item types. Just do:

Mapper.CreateMap<SentEmailAttachment, SentEmailAttachmentItem>();
var attachments = Mapper.Map<IEnumerable<SentEmailAttachment>, List<SentEmailAttachmentItem>>(someList);

That will work just fine.