c# - 添加显示错误消息的条件

Question

晚上好大家，

我想知道检查名称是否存在于数据库中的最佳方法是什么，如果是，我将使用 JSON 显示错误。注意：（检查是否存在）将用于添加新项目和更新项目。

public async Task<IActionResult> AddOrEdit(int id = 0)
        {
            if (id == 0)
                return View(new TransactionModel());
            else
            {
                var transactionModel = await _context.Transactions.FindAsync(id);
                if (transactionModel == null)
                {
                    return NotFound();
                }
                return View(transactionModel);
            }
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> AddOrEdit(int id, [Bind("TransactionId,AccountNumber,BeneficiaryName,BankName,SWIFTCode,Amount,Date")] TransactionModel transactionModel)
        {
            if (ModelState.IsValid)
            {
                //Insert
                if (id == 0)
                {
                    transactionModel.Date = DateTime.Now;
                    _context.Add(transactionModel);
                    await _context.SaveChangesAsync();

                }
                //Update
                else
                {
                    try
                    {
                        _context.Update(transactionModel);
                        await _context.SaveChangesAsync();
                    }
                    catch (DbUpdateConcurrencyException)
                    {
                        if (!TransactionModelExists(transactionModel.TransactionId))
                        { return NotFound(); }
                        else
                        { throw; }
                    }
                }
                return Json(new { isValid = true, html = Helper.RenderRazorViewToString(this, "_ViewAll", _context.Transactions.ToList()) });
            }
            return Json(new { isValid = false, html = Helper.RenderRazorViewToString(this, "AddOrEdit", transactionModel) });
        }

标签： c#asp.net