Map list of ids to list of objects with id property

[kolpav]

I have run out of places where to ask sorry for spamming issues with questions.

Source/destination types

Source: Guid
Destination: objects implementing interface IEntity { Guid Id { get; set; } }

Mapping configuration

I have tried a lot of solutions mainly configuring ForAllPropertyMaps where I am checking if source is List<Guid> and destination implements IEntity but I can't seem to get it right.

Versions

<PackageReference Include="AutoMapper" Version="10.1.1" />
<PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="8.1.1" />

Expected behavior

interface IEntity
{
  Guid Id { get; set; }
}

public class User : IEntity
{
  public Guid Id { get; set; }
  public List<Comment> Comments { get; set; }
}

public class CreateUserCommand
{
  public Guid Id { get; set; }
  public List<Guid> CommentIds { get; set; } // Ids of comments which are already in db
}

CreateMap<CreateUserCommand, User>()
  .ForMember(x => x.Comments, opt => opt.MapFrom(x => x.CommentIds));


var user = mapper.Map<User>(createUserCommand);

Mapping I am trying to achieve is:

(CreateUserCommand command) => new User
{
  Id = command.Id,
  Comments = command.CommentIds.Select(id => new Comment { Id = id })
}

its shown for concrete type User but I would like it to work for any class implementing IEntity interface meaning class that has Guid Id

Actual behavior

Mapping throws an error.

Steps to reproduce

Here is fiddle with one of my many attempts

https://dotnetfiddle.net/Widget/vvmnog

I think I am trying to achieve something which should be very common your DTOs contains list of ids but your entity has list of entities and I would like to map to them such that they have only Id property set which is all you need to provide to entity framework db context.

Here is example command handler for type of code I have in my app

public async Task<User> Handle(CreateUserCommand command, CancellationToken cancellationToken)
{
  var user = _mapper.Map<User>(command);
  _context.Comments.AttachRange(user.Comments);
  await _context.Users.AddAsync(user, cancellationToken);
  await _context.SaveChangesAsync(cancellationToken);
  return user
}

I was able to make it work by handwriting map for every class implementing IEntity like so:

.ForMember(x => x.Comments, opt => opt.MapFrom(x => x.CommentIds.Select(id => new Comment { Id = id })));

but I feel there must be more generic solution.

[Cubelaster]

You can try this, or something along those lines.
https://docs.automapper.org/en/stable/Custom-type-converters.html

There are more examples on the docs.