CODEWITHSUNDEEP
c#mappingautomappernullable
Adam Levitt
Adam Levitt

Reputation: 10476

AutoMapper not updating a nullable long? to null

I have the following two classes:

public class DomainStudent {
    public long Id { get; set; }
    public string AdvisorId { get; set; }
    public long? DegreeId { get; set; }
}

public class ApiStudent {
    public long Id { get; set; }
    public long AdvisorName { get; set; }
    public long? DegreeId { get; set; }
}

When I run the following mapping:

Mapper.CreateMap<ApiStudent, DomainStudent>();

var api = new ApiStudent();
api.Id = 123;
api.AdvisorName = "Homer Simpson";
api.DegreeId = null;

var domain = new DomainStudent();
domain.Id = 123;
domain.AdvisorName = "Marge Simpson";
domain.DegreeId = 5; // i want this to get written to null

Mapper.Map(api, domain);
// at this point domain.DegreeId = 5 instead of null

I would have thought this worked by default. Am I missing something?

Upvotes: 0

Views: 421

Answers (1)

Tom Studee
Tom Studee

Reputation: 10452

By default automapper will ignore null source values.

You can change this with the following:

Mapper.Initialize( Conf =>
  {
    Conf.ForSourceType<ApiStudent>().AllowNullDestinationValues = true;
  } );

Otherwise you can try:

Mapper.CreateMap<long?, long?>()
    .ConvertUsing(v => v);

Pretty ugly hack to have to do something like this but it might work.

edit: Just for clarity I wanted to note the final solution to the question was upgrading to AutoMapper version 3.2.1

Upvotes: 4

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