Excluding properties from update instead of updating whole object

you are on the wrong path! it's very simple to update an entity with the specified fields.

1- Create a DTO.

2- Configure mapping

3- Get entity and map DTO to entity.

Checkout my example. In this example Student entity has 3 properties. In the StudentAppService UpdateOnlyNameOfStudent() method, we update only Name field of Student. And notice that I even didn't run _studentRepository.Update(student) because AspNet Boilerplate commits the changes when the method ends (See automatic save change)

StudentDto.cs

[AutoMapFrom(typeof(Student))]
public class StudentDto: EntityDto<long>
{
     public string Name { get; set; }    
}

Student.cs

public class Student: Entity
{
     public string Name { get; set; }  

     public int SchoolNumber { get; set; }  

     public DateTime RegisterDate { get; set; }  
}

StudentAppService.cs

public class StudentAppService : IStudentAppService 
{
    private readonly IRepository<Student> _studentRepository;


    public RoleAppService(IRepository<Student> studentRepository)
    {
       _studentRepository = studentRepository;
    }

    public override async void UpdateOnlyNameOfStudent(StudentDto input)
    {
        var student = _studentRepository.Get(input.Id);
        ObjectMapper.Map(input, student);
    }

    /*
    public override async void UpdateOnlyNameOfStudent_Alternative(StudentDto input)
    {
        var student = _studentRepository.Get(input.Id);
        student.Name = input.Name;            
    }
    */
}

AspNet Boilerplate uses AutoMapper to map objects. See Object To Object Mapping