业务Object转DTO

Question

I have a list of type Application . I want to transform that object to an object of type ApplicationDTO . Inside that Application business object, there is a list of Applicants of the type Applicant . Now my DTO has the same list but I am struggling on how to assign the list members of the business object to the list inside the DTO. I have multiple such occurences where it is not known how many items I have in the list.
Here is an example:

// List of business objects
List<Application> ApplicationList = await _dbContextDigitVP.Applications.FromSqlRaw("Exec dbo.GetApplication {0}", id).ToListAsync();

//DTO object
ApplicationDTO applicationDTO = new ApplicationDTO
{
    ApplicationNumber = Application.ApplicationNumber,
    Country = Application.Country,
    ApplicationUuid = Application.ApplicationUuid,
    PwEmployeeAdUserName = Application.PwEmployeeAdUserName,
    Category = new ApplicationCategoryDTO
    {
        Category = Application.Category?.Category
    },
    Applicants = new List<ApplicantDTO>()
    {
       // add members of business object                       
    }

};

I could go over it with a for loop but is there a way to do this inside the object definition?

Answer 1

You can use Automapper to map data from one object to another.

Create Automapper configurations like this for the configure mapping between the ApplicationDTO and Application , ApplicationCategory and ApplicationCategoryDTO and Applicant to ApplicantDTO

var configuration = new MapperConfiguration(cfg => {

  //Source ==> Desti
  //Application and ApplicationDTO classes
  cfg.CreateMap < Application, ApplicationDTO > ()
    .ForMember(dest => dest.Category, opt => opt.MapFrom(src => src.Category))
    .ForMember(dest => dest.Applicants, opt => opt.MapFrom(src => src.Applicants));
  //ApplicationCategory and ApplicationCategoryDTO classes
  cfg.CreateMap < ApplicationCategory, ApplicationCategoryDTO > ();
  //Applicant and ApplicantDTO classes
  cfg.CreateMap < Applicant, ApplicantDTO > ();
});

In your constructor, you can initialize Mapper like

private readonly IMapper _Mapper;

   public TestController(IMapper mapper) {
            _Mapper = mapper;
   }

When you doing the casting you can do somthing like this,

var applicationDTOList = _Mapper.Map<List<ApplicationDTO>>(ApplicationList);

Answer 2

You can use AutoMapper .

Once you have your types you can create a map for the two types using a MapperConfiguration and CreateMap. You only need one MapperConfiguration instance typically per AppDomain and should be instantiated during startup.

var config = new MapperConfiguration(cfg => cfg.CreateMap<Application, 
ApplicationDTO>());

The type on the left is the source type, and the type on the right is the destination type. To perform a mapping, call one of the Map overloads:

var mapper = config.CreateMapper();
// or
var mapper = new Mapper(config);
ApplicationDTO dto = mapper.Map<ApplicationDTO>(Application);

Answer 3

you can also use LINQ to transform objects like without using AutoMapper.

List<ApplicationDTO> applicationDTOList = ApplicationList.Select(app => new ApplicationDTO
{
    ApplicationNumber = app.ApplicationNumber,
    Country = app.Country,
    ApplicationUuid = app.ApplicationUuid,
    PwEmployeeAdUserName = app.PwEmployeeAdUserName,
    Category = new ApplicationCategoryDTO
    {
        Category = app.Category?.Category
    },
    Applicants = app.Applicants.Select(a => new ApplicantDTO
    {
        // same logic as the above
    }).ToList()
}).ToList();