public async Task <TrainModel> CreateTrainAsync(TrainModel trainModel) { if (trainModel is null) { throw new ArgumentNullException(nameof(trainModel)); } var trainEntity = new Data.Entities.Train { TrainName = trainModel.TrainName }; trainEntity = await _trainRepository.AddAsync(trainEntity); return(new TrainModel { TrainId = trainEntity.TrainId, TrainName = trainEntity.TrainName, //Wagons = trainEntity.Wagons // .Select(x => new WagonModel() { WagonId = x.WagonId }) // .ToList() }); }