模型在MVC中發佈後沒有綁定？

Question

我想從提交中總結兩個數字。 HTTPGET工作正常，但是，我不能顯示它在視圖形式提交..

public class CalculatorController : Controller 
    { 
     // 
     // GET: /Calculator/ 

     public ActionResult Index() 
     { 
      return View(); 
     } 
     [HttpGet] 
     public ActionResult Sum() 
     { 
      CalculatorModel model = new CalculatorModel(); 
      model.FirstOperand = 3; 
      model.SecondOperand = 4; 
      model.Result = model.FirstOperand + model.SecondOperand; 
      //Return the result 
      return View(model); 
     } 

     [HttpPost] 
     public ActionResult Sum(CalculatorModel model) 
     { 
      model.Result = model.FirstOperand + model.SecondOperand; 
      //Return the result 
      return View(model); 
     } 

    } 

---

@model HTMLHelpersDemo.Models.CalculatorModel 
@{ 
    ViewBag.Title = "Sum"; 
} 

<h2>Sum</h2> 

@using (Html.BeginForm("Sum", "Calculator", FormMethod.Post)) 
{ 
    <table border="0" cellpadding="3" cellspacing="1" width="100%"> 
     <tr valign="top"> 
      <td> 
       @Html.LabelFor(model => model.FirstOperand) 
       @Html.TextBoxFor(model => model.FirstOperand) 
      </td> 
     </tr> 
     <tr valign="top"> 
      <td> 
       @Html.LabelFor(model => model.SecondOperand) 
       @Html.TextBoxFor(model => model.SecondOperand) 
      </td> 
     </tr> 
     <tr valign="top"> 
      <td> 
       @Html.LabelFor(model => model.Result) 
       @Html.TextBoxFor(model => model.Result) 
      </td> 
     </tr> 
    </table> 
    <div style="text-align:right;"> 
     <input type="submit" id="btnSum" value="Sum values" /> 
    </div> 
} 

最初它顯示7 3加4

，但是當我改變了我值併發布它不顯示舊值..在控制器中調試它顯示完美但無法正常顯示

Answer 1

您需要從模型狀態字典中清除以前的結果值。您可以使用ModelState.Clear()方法來做到這一點。

[HttpPost] 
public ActionResult Sum(CalculatorModel model) 
{ 
    ModelState.Clear(); 
    model.Result = model.FirstOperand + model.SecondOperand;   
    return View(model); 
}