public async Task <ShopOperationResult> CreateAsync(PurchaseInvoice item) { if (item == null) { throw new ArgumentNullException(nameof(item)); } _db.PurchaseInvoices.Add(item); try { await _db.SaveChangesAsync(); } catch { return(ShopOperationResult.Failed(_errorDescriber.DefaultError())); } return(ShopOperationResult.Success); }