使用AutoMapper从实体映射到DTO或DTO到实体时出错

Question

I'm using EntityFramework as a DataLayer and DTO to transfer data between layer. I develop Windows Forms in N-Tier architecture and when I try to mapping from Entity to DTO in BLL:

public IEnumerable<CategoryDTO> GetCategoriesPaged(int skip, int take, string name)
{
    var categories = unitOfWork.CategoryRepository.GetCategoriesPaged(skip, take, name);
    var categoriesDTO = Mapper.Map<IEnumerable<Category>, List<CategoryDTO>>(categories);

    return categoriesDTO;
}

I've got this error: http://s810.photobucket.com/user/sky3913/media/AutoMapperError.png.html

The error said that I missing type map configuration or unsupported mapping. I have registered mapping using profile in this way at UI Layer:

[STAThread]
static void Main()
{
    AutoMapperBusinessConfiguration.Configure();
    AutoMapperWindowsConfiguration.Configure();
    ...
    Application.Run(new frmMain());
}

and AutoMapper configuration is in BLL:

public class AutoMapperBusinessConfiguration
{
    public static void Configure()
    {
        Mapper.Initialize(cfg =>
        {
            cfg.AddProfile<EntityToDTOProfile>();
            cfg.AddProfile<DTOToEntityProfile>();
        });
    }
}

public class EntityToDTOProfile : Profile
{
    public override string ProfileName
    {
        get { return "EntityToDTOMappings"; }
    }

    protected override void Configure()
    {
        Mapper.CreateMap<Category, CategoryDTO>();
    }
}

public class DTOToEntityProfile : Profile
{
    public override string ProfileName
    {
        get { return "DTOToEntityMappings"; }
    }

    protected override void Configure()
    {
        Mapper.CreateMap<CategoryDTO, Category>();
    }
}

I've got the same error too when mapping from DTO to Entity.

category = Mapper.Map<Category>(categoryDTO);

How to solve this?

Answer 1

Its because you are using Mapper.Initialize multiple times. If you look at the source code it calls Mapper.Reset() which means only the last mapping defined will work. so instead simply remove the Initialize calls and replace with Mapper.AddProfile< >

Answer 2

Use AutoMapper.AssertConfigurationIsValid() after the Configure() calls. If anything fails it will throw an exception with a descriptive text. It should give you more info to debug further.

Answer 3

Mapping DTOs to Entities using AutoMapper and EntityFramework

here we have an Entity class Country and an CountryDTO

 public class Country
 {
     public int CountryID { get; set; }
     public string ContryName { get; set; }
     public string CountryCode { get; set; }
 }

CountryDto

 public class CountryDTO
{
   public int CountryID { get; set; }
   public string ContryName { get; set; }
   public string CountryCode { get; set; }
}

Create Object of CountryDTO

CountryDTO collection=new CountryDTO();
 collection.CountryID =1;
 collection.ContryName ="India";
 collection.CountryCode ="in";

Country model = Convertor.Convert<Country, CountryDTO>(collection);
dbcontext.Countries.Add(model);
dbcontext.SaveChanges();

this will work fine for a new Country, the above code will map CountryDTO to Country Entity Object and add new entities to the dbcontext and save the changes.

using System.Reflection;
public static TOut Convert<TOut, TIn>(TIn fromRecord) where TOut : new()
 {
  var toRecord = new TOut();
  PropertyInfo[] fromFields = null;
  PropertyInfo[] toFields = null;

  fromFields = typeof(TIn).GetProperties();
  toFields = typeof(TOut).GetProperties();

  foreach (var fromField in fromFields)
   {
    foreach (var toField in toFields)
      {
        if (fromField.Name == toField.Name)
          {
             toField.SetValue(toRecord, fromField.GetValue(fromRecord, null), null);
            break;
          }
      }

  }
return toRecord;
}

public static List<TOut> Convert<TOut, TIn>(List<TIn> fromRecordList) where TOut : new()
 {
  return fromRecordList.Count == 0 ? null : fromRecordList.Select(Convert<TOut, TIn>).ToList();
 }

http://bhupendrasinghsaini.blogspot.in/2014/09/convert-enity-framwork-data-in-entity.html