Mapping from EF entities to gRPC Protobuf messages - entity-framework

Question

I've started experimenting with gRPC and I would like to be able to map my db entities to protobuf messages using automapper. But I can't figure out how to map the repeated fields.
My message definitions looks like this:
message WorklistResponse {
repeated WorklistMessage Worklists = 1;
}
message WorklistMessage {
int32 WorklistId = 1;
repeated CollectionWorkMessage Work = 2;
}
message CollectionWorkMessage {
int32 WorkId = 1;
string AddressComment = 2;
}
And I'm trying to map from an entity that looks like this:
[Table("Worklist")]
public sealed class DbWorklist
{
public DbWorklist()
{
Work = new HashSet<DbWork>();
}
[Key]
public int WorklistId { get; set; }
public ICollection<DbWork> Work { get; set; }
}
Where the related entities DbWork is an abstract baseclass to DbCollectionWork and look like this:
[Table("Work")]
public abstract class DbWork
{
[Key]
public int WorkId { get; set; }
public int WorklistId { get; set; }
[ForeignKey(nameof(WorklistId))]
public DbWorklist Worklist { get; set; }
}
public sealed class DbCollectionWork : DbWork
{
[StringLength(255)]
public string AddressComment { get; set; }
}
I have two mappings configured:
cfg.CreateMap<DbWorklist, WorklistMessage>();
cfg.CreateMap<DbCollectionWork, CollectionWorkMessage>();
I can do this:
var worklists = dbContext.Worklists.Include(wl => wl.Work).ToList();
var worklistWork = autoMapper.Map<List<CollectionWorkMessage>>(worklists[0].Work);
var worklistResponse = new WorklistResponse
{
Worklists = { new WorklistMessage
{
Work = { worklistWork }
}}
};
This seems to be the only way I can set the Work property which is a protobuf3 RepeatedField<CollectionWorkMessage> that becomes a read-only property in the autogenerated protobuf class.
I would like to be able to construct my message using automapper.
I'm using AutoMapper 8.0, Grpc 1.19.0, Protobuf 3.7.0 and EF Core 2.2.4