AutoMapper overrides source properties

Question

I have the following code to update Student entity:

using static AutoMapper.Mapper;
...
public void Update(StudentInputDto dto)
{
   Student student = _studentRepository.GetStudent();
   student = Map<Student>(dto); //student.studentnumer is null here :(
   _studentRepository.Update(student);
}

My student Entity:

public class Student
{
   public Guid studentid { get; set; }
   public string firstname { get; set; }
   public string lastname { get; set; }
   public int age { get; set; }
   public Guid genderid { get; set; }
   public string studentnumber { get; set; }
}

My StudentInputDto:

public class StudentInputDto
{
   public string FirstName { get; set; }
   public string LastName { get; set; }
   public int Age { get; set; }
   public Guid GenderId { get; set; }
}

The problem is that Student.studentnumber is null after the mapping.

I want to configure AutoMapper in such a way that Student.studentnumber is preserved after the mapping. How to do it ? Any help would be greatly appreciated.

My initial thought was to configure AutoMapper in a following way:

Mapper.Initialize(cfg => {
   cfg.CreateMap<StudentInputDto, Student>()
      .ForMember(dest => dest.studentnumber, opt => opt.Ignore());
});

But that configuration, does not solve the problem.

Possible duplicate of [Automapper - can it map over only existing properties in source and destination objects?](https://stackoverflow.com/questions/17147099/automapper-can-it-map-over-only-existing-properties-in-source-and-destination) — Yeldar Kurmangaliyev, Jul 28 '17 at 03:24

score 3 · Accepted Answer · answered Jul 28 '17 at 03:59

Take a look at method description of Automapper.

TDestination Map<TDestination>(object source);

Execute a mapping from the source object to a new destination object. The source type is inferred from the source object.

student = Map<Student>(dto) will create a new Student object and assign to student variable

To map two existing objects use Mapper.Map(dto, student); instead

TDestination Map<TSource, TDestination>(TSource source, TDestination destination)

Execute a mapping from the source object to the existing destination object.

AutoMapper overrides source properties

1 Answers1