Linq set null to a value with automapper

Question

I have a ticket that contains messages. Also, the ticket model contains a a resolutionMessage that is a message that can be nullable. I want to do something like that : ``` Mapper.CreateMap<Ticket, TicketModel>() .ForMember(dest => dest.ResolutionMessage, opt => opt.MapFrom(src => { if (src.ResolutionMessageID != null) { src.Messages.Where(m => m.MessageID == src.ResolutionMessageID); } else // Return null; } )); ``` Second attempt : ``` .ForMember(dest => dest.ResolutionMessage, opt => { (opt.MapFrom(src => if(src.ResolutionMessageID != null) opt.MapFrom(src => src.Messages.Where(m => m.MessageID == src.ResolutionMessageID)); else opt => opt.Ignore(); } ); ``` Any ideas?

Accepted Answer

I will consider `ResolutionMessageID` is a nullable type, you can try something like this:

```
.ForMember(dest => dest.ResolutionMessage, opt => opt.MapFrom(src => src.ResolutionMessageID.HasValue ? src.Messages.Where(m => m.MessageID == src.ResolutionMessageID) : null));
```

If it is not a nullable type and allow null:

```
.ForMember(dest => dest.ResolutionMessage, opt => opt.MapFrom(src => src.ResolutionMessageID != null ? src.Messages.Where(m => m.MessageID == src.ResolutionMessageID.Value) : null));
```

Or you use `opt.MapFrom()` or `opt.Ignore()`, there is not way to use both. I think it is better keep the null value when the condition for you map does not accept the rule. If you use, `opt.Ignore()` will ignore the property on conversion of objects.

Linq set null to a value with automapper

Solution

Problem