Automapper many to many mapping

Question

Patrick, thanks for advice about correct question!

EDIT 1:

I have three table for many to many relationship. Like this: EF data model

GoodEntity:

public partial class GoodEntity
{
    public GoodEntity()
    {
        this.GoodsAndProviders = new HashSet<GoodAndProviderEntity>();
    }

    public int id { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public decimal cost { get; set; }
    public Nullable<decimal> price { get; set; }

    public virtual ICollection<GoodAndProviderEntity> GoodsAndProviders { get; set; }
}

ProviderEntity:

public partial class ProviderEntity
{
    public ProviderEntity()
    {
        this.GoodsAndProviders = new HashSet<GoodAndProviderEntity>();
    }

    public int id { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public string address { get; set; }
    public string phone { get; set; }
    public string email { get; set; }
    public string url { get; set; }
    public Nullable<int> rating { get; set; }

    public virtual ICollection<GoodAndProviderEntity> GoodsAndProviders { get; set; }
}

Entity for many-to-many relationship:

public partial class GoodAndProviderEntity
{
    public int id { get; set; }
    public int good_id { get; set; }
    public int provider_id { get; set; }

    public virtual GoodEntity Goods { get; set; }
    public virtual ProviderEntity Providers { get; set; }
}

GoodDTO:

public class GoodDTO
{
    public int id { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public decimal cost { get; set; }
    public decimal? price { get; set; }

    public IList<ProviderDTO> providers { get; set; }
}

ProviderDTO:

public class ProviderDTO
{
    public int id { get; set; }
    public string name { get; set; }
    public string description { get; set; }
    public string address { get; set; }
    public string phone { get; set; }
    public string email { get; set; }
    public string url { get; set; }
    public int? rating { get; set; }
}

This is code for creation maps:

Mapper.CreateMap<ProviderDTO, ProviderEntity>();
Mapper.CreateMap<ProviderEntity, ProviderDTO>();

Mapper.CreateMap<GoodEntity, GoodDTO>()
      .ForMember(dto => dto.providers, opt => opt.MapFrom(x => x.GoodsAndProviders));
Mapper.CreateMap<GoodAndProviderEntity, ProviderDTO>();

And it works half. Automapper was mapped "goods" completely and was created list for all providers for this goods. But automapper don`t fill providers. enter image description here

If I use Mapper.AssertConfigurationIsValid(), then:

Unmapped members were found. Review the types and members below. Add a custom mapping expression, ignore, add a custom resolver, or modify the source/destination type ======================================================= ProviderDTO -> ProviderEntity (Destination member list) Core.DTO.ProviderDTO -> DAL.EF.Entities.ProviderEntity (Destination member list) Unmapped properties: GoodsAndProviders ============================================================== GoodAndProviderEntity -> ProviderDTO (Destination member list) DAL.EF.Entities.GoodAndProviderEntity -> Core.DTO.ProviderDTO (Destination member list)

How to create mapping for many-to-many relationship?

Regards, Anton

What happens when you use Shift + F12 on the companies variable? That should tell you where it's defined. — Andrew Whitaker
Andrew, I can't do it, because I haven't source code from answer. — Hellaren
I suggest a few edits to help get an answer: 1) Remove the beginning of your question where you reference the answer of another SO question. Without seeing all of the code, we can't tell you where companies is coming from. 2) Please provide complete definitions of your source and destination classes (not just a graphic of how they are related). 3) Show how you're mapping, sample data and where the mapping is failing. 4) Make sure you're calling Mapper.AssertConfigurationIsValid() to make sure your mapping is configured properly. — PatrickSteele

Sitl Sitl · Accepted Answer · 2015-09-08T16:27:49

With your current code you're trying to map the GoodAndProviderEntity into ProviderDTO.

Mapper.CreateMap<GoodEntity, GoodDTO>()
  .ForMember(dto => dto.providers, opt => opt.MapFrom(x => x.GoodsAndProviders));

What you want to do, is to map ProviderEntity into ProviderDTO, so all you have to do is select the Providers from GoodsAndProviders as a list:

    Mapper.CreateMap<GoodEntity, GoodDTO>()
      .ForMember(dto => dto.providers, opt => opt.MapFrom(x => x.GoodsAndProviders.Select(y => y.Providers).ToList()));

Automapper many to many mapping

1 Answers