Automapper and Open Generics

Question

I'm trying to use Automapper's Open Generics as described in https://github.com/AutoMapper/AutoMapper/wiki/Open-Generics to perform a mapping between User and Account.

public class User
{
    public Guid UserId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime Dob { get; set; }
}

public class Account
{
    public Guid UserId { get; set; }
    public string FirstName { get; set; }
}

I created the Source and Destination

public class Source<T>
{
    public T Value { get; set; }
}

public class Destination<T>
{
    public T Value { get; set; }
}

I want to perform the mapping in an AccountService

public class AccountService
{
    private User user1 = new User{FirstName = "James", LastName = "Jones", Dob = DateTime.Today, UserId = new Guid("AC482E99-1739-46FE-98B8-8758833EB0D2")};

    static AccountService()
    {
        Mapper.CreateMap(typeof(Source<>), typeof(Destination<>));
    }

    public T GetAccountFromUser<T>()
    {
        var source = new Source<User>{ Value = user1 };
        var destination = Mapper.Map<Source<User>, Destination<T>>(source);
        return destination.Value;
    }
}

But I get an exception

Missing type map configuration or unsupported mapping.

Mapping types: User -> Account OpenGenerics.Console.Models.User -> OpenGenerics.Console.Models.Account

Destination path: Destination`1.Value.Value

Source value: OpenGenerics.Console.Models.User

I confirmed the approach in https://github.com/AutoMapper/AutoMapper/wiki/Open-Generics works for int and double

Edit This might be a solution for me, it's a little messy though.

    var mappingExists = Mapper.GetAllTypeMaps().FirstOrDefault(m => m.SourceType == typeof (User) && m.DestinationType == typeof (T));
    if (mappingExists == null)
        Mapper.CreateMap<User, T>();

score 2 · Accepted Answer · answered Aug 05 '15 at 15:15

2

For closed generics, the type parameters also need to be able to be mapped. Add this:

Mapper.CreateMap<User, Account>();

And you're set.

answered Aug 05 '15 at 15:15

Jimmy Bogard

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Was hoping that was not the case! In my real application the Account is defined in the MVC project and the User is defined in the Service project. The Service project does NOT have reference to the MVC project so I can't map the way you suggest. I can do this Mapper.CreateMap(); but this is executed for every call to the GetAccountFromUser() method. – Bryan Aug 05 '15 at 15:24
1

Ugh. I hate project layouts like this. Just put everything in one project and use folders. – Jimmy Bogard Aug 05 '15 at 15:57
That ship has sailed! – Bryan Aug 05 '15 at 17:08
Added a potential solution to the question – Bryan Aug 05 '15 at 17:50

Automapper and Open Generics

1 Answers1