Automapper: Checking for null in MapFrom

Question

Using version 4.

How do I check for null when doing a map? I tried the .Value, but that's not there on a Null:

        Mapper.CreateMap<Agenda, AgendaViewModel>()
            .ForMember(x => x.DateApproved, 
               y => y.MapFrom(s =>  DateTime.SpecifyKind(s.DateApproved.Value, DateTimeKind.Utc)));

Check this, use ResolveUsing solution for the better performance of the code: http://stackoverflow.com/a/35972650/1559611 — Mrinal Kamboj, Jul 07 '16 at 06:48

score 12 · Accepted Answer · answered Jul 07 '16 at 05:20

12

Alternatively, you can just check the HasValue property prior to mapping:

Mapper.CreateMap<Agenda, AgendaViewModel>()
     .ForMember(x => x.DateApproved,
                y => y.MapFrom(s => s.DateApproved.HasValue ?
                                    DateTime.SpecifyKind(s.DateApproved.Value, DateTimeKind.Utc) :
                                    DateTime.UtcNow));

answered Jul 07 '16 at 05:20

Will Ray

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Is z.DateApproved.HasValue same as null check, can't we do simple null check here – Mrinal Kamboj Jul 07 '16 at 06:45
For such scenario ResolveUsing would be a preferred call – Mrinal Kamboj Jul 07 '16 at 06:49

score 2 · Answer 2 · answered Jul 07 '16 at 05:18

2

I think this would work:

Mapper.CreateMap<Agenda, AgendaViewModel>()
        .ForMember(x => x.DateApproved, 
                    y => y.ResolveUsing(z => z.DateApproved.HasValue 
                           ? DateTime.UtcNow :
                           Mapper.Map<Agenda, AgendaViewModel>
                          (DateTime.SpecifyKind(z.DateApproved.Value, DateTimeKind.Utc)));

answered Jul 07 '16 at 05:18

Zein Makki

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Is z.DateApproved.HasValue same as null check, can't we do simple null check here – Mrinal Kamboj Jul 07 '16 at 06:45
@MrinalKamboj Compiler will convert `== null` to .`HasValue` for Nullable types. So it is the same. – Zein Makki Jul 07 '16 at 06:54

Automapper: Checking for null in MapFrom

2 Answers2

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