public async Task <IActionResult> Post()
        {
            var models = await _fileParser.CreateTransactionModelFromFile(Request.Form.Files[0]);

            var modelState = TransactionModelValidator.ValidateModels(ModelState, models);

            if (!modelState.IsValid)
            {
                return(BadRequest(modelState));
            }

            var modelsToImport = models.Select(e => _mapper.Map <Transaction>(e));
            await _transactionImporter.ImportTransactions(modelsToImport);

            return(Ok("File has been successfully imported."));
        }