AutoMapper_ProjectTo_example.cs

    public class Requirement : BaseEntity
    {
        public DateTime CreateDate { get; set; }
        public decimal? MinPrice { get; set; }
        public decimal? MaxPrice { get; set; }

        public ICollection<Contact> Contacts { get; set; }
        public Country Country { get; set; }
    }
    
    public class Contact : BaseEntity
    {
        public string FirstName { get; set; }

        public string Surname { get; set; }

        public ICollection<Requirement> Requirements { get; set; }
    }
    
    public class Country : BaseEntity{
        public string Name { get; set; }
    }
    
    public RequirementResult {
        public Guid Id { get; set; }
        public DateTime CreateDate { get; set; }
        public decimal? MinPrice { get; set; }
        public decimal? MaxPrice { get; set; }
        public string CountryName { get; set; }

        public IEnumerable<ContactResult> Contacts { get; set; }
    }
    
    public ContactResult {
        public string FirstName { get; set; }

        public string Surname { get; set; }
    }
    
    public RequirementResultProfile : Profile {
        public RequirementResultProfile() {
            Mapper.CreateMap<Requirement, RequirementResult>()
                .ForMember(el => el.CountryName, m => m.MapFrom(el => el.Country.Name));
        }
    }
    
    public ContactResultProfile : Profile {
        public ContactResultProfile() {
            Mapper.CreateMap<Contact, ContactResult>();
        }
    }
    
    public GetRequirementQueryHandler : IRequestHandler<int, RequirementResult> {
        public RequirementResult Handle(int id){
        
            RequirementResult requirement = 
              this.requirementRepository
                .Get()
                .ProjectTo<RequirementResult>()
                .FirstAsync(el => el.Id == id);
            
            return requirement;
        }
    }