Auto mapper to map conditional entity which doesn't work without using After map

Question

Hi I am using Auto mapper to map conditional entity which doesn't work without using After map but works fine with After Map which I don't won't to use. I want to map InvoiceLineCreditHeader from Domain.PermanentPlacement but conditionally.

Following is Mapping code.

 MauritiusMapper.CreateMap<Domain.PermanentPlacement, InvoiceLineCreditHeader>()
                                .ForMember(desc => desc.ApplicantName, o => o.MapFrom(source => source.Candidate.FullName))
                                .ForMember(desc => desc.DatePlaced, o => o.MapFrom(source => source.PlacementDate))
                                .ForMember(desc => desc.ApproveDate, o => o.MapFrom(source => source.LastAuditItem.DateOfAction))
                                .ForMember(desc => desc.CheckedBy, o => o.MapFrom(source => source.StartCheckedBy))
                                .ForMember(desc => desc.Job, o => o.MapFrom(source => source.JobTitle));

        MauritiusMapper.CreateMap<InvoiceLineCreditSearchResult, InvoiceLineCreditData>()
            .ForMember(d => d.InvoiceLineCredits, o => o.MapFrom(s => s.Credits))
            .ForMember(d => d.InvoiceLineCreditHeader, o => o.MapFrom(s => s.InvoiceLine))
            .ForMember(d => d.CreditReasons, o => o.MapFrom(s => s.CreditReasons))
            .ForMember(d => d.CreditStatuses, o => o.MapFrom(s => s.CreditStatuses))
            .ForMember(d => d.InvoiceLineCreditHeader, o => o.MapFrom(s => s.InvoiceLine.TransactionLines.OfType<PermanentPlacementTransactionLine>().FirstOrDefault()?.PermanentPlacement ?? s.ReissuePermanentPlacement))

This give error

An expression tree lambda may not contain a null propagating operator.

Which is explained by Why can't I use the null propagation operator in lambda expressions?

if I use Aftermap , it works fine.

        MauritiusMapper.CreateMap<InvoiceLineCreditSearchResult, InvoiceLineCreditData>()
            .ForMember(d => d.InvoiceLineCredits, o => o.MapFrom(s => s.Credits))
            .ForMember(d => d.InvoiceLineCreditHeader, o => o.MapFrom(s => s.InvoiceLine))
            .ForMember(d => d.CreditReasons, o => o.MapFrom(s => s.CreditReasons))
            .ForMember(d => d.CreditStatuses, o => o.MapFrom(s => s.CreditStatuses))
            //.ForMember(d => d.InvoiceLineCreditHeader, o => o.MapFrom(s => s.InvoiceLine.TransactionLines.OfType<PermanentPlacementTransactionLine>().FirstOrDefault()?.PermanentPlacement ?? s.ReissuePermanentPlacement))
            .AfterMap((s, d) =>
            {
                var placement
                = s.InvoiceLine.TransactionLines.OfType<PermanentPlacementTransactionLine>().FirstOrDefault()?.PermanentPlacement ?? s.ReissuePermanentPlacement;
                //  if (placement == null) return;


                d.InvoiceLineCreditHeader.ApplicantId = placement.ApplicantId;
                d.InvoiceLineCreditHeader.ApplicantName = placement.Candidate.FullName;
                d.InvoiceLineCreditHeader.Job = placement.JobTitle;
                d.InvoiceLineCreditHeader.DatePlaced = placement.PlacementDate;
                d.InvoiceLineCreditHeader.PlacedBy = placement.PlacedBy;
                d.InvoiceLineCreditHeader.ApprovedBy = placement.ApprovedBy;
                d.InvoiceLineCreditHeader.ApproveDate = placement.LastAuditItem.DateOfAction;
                d.InvoiceLineCreditHeader.CheckedBy = placement.StartCheckedBy;
                d.InvoiceLineCreditHeader.StartDate = placement.StartDate;
            });

Is There any way in auto mapper I can achieve this without using AfterMap ? there is condition as well but it is also using linq expression.

Any ideas ?

score 3 · Accepted Answer · answered Feb 16 '17 at 09:15

You need to find alternative to ?. operator in

s.InvoiceLine.TransactionLines.OfType<PermanentPlacementTransactionLine>()
    .FirstOrDefault()?.PermanentPlacement

which is quite simple by Select-ing PermanentPlacement before FirstOrDefault:

s.InvoiceLine.TransactionLines.OfType<PermanentPlacementTransactionLine>()
    .Select(e => e.PermanentPlacement).FirstOrDefault()

score 2 · Answer 2 · answered Feb 16 '17 at 09:22

You could create a separate method with the desired logic:

private InvoiceLineCreditHeader GetInvoiceLineCreditHeader(InvoiceLineCreditSearchResult result)
{
    // todo: get InvoiceLineCreditHeader conditionally
    InvoiceLineCreditHeader header = new InvoiceLineCreditHeader();
    return header;
}

and call it like this:

.ForMember(d => d.InvoiceLineCreditHeader, o => o.MapFrom(s => GetInvoiceLineCreditHeader(s)))

Auto mapper to map conditional entity which doesn't work without using After map

2 Answers2