是否Html.TextBox使用Request.Params，而不是模式？

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问题描述

我有一个简单的测试应用程序：

I have a simple test application:

型号：

public class Counter
{
    public int Count { get; set; }

    public Counter()
    {
        Count = 4;
    }
}

控制器：

public class TestController : Controller
{
    public ActionResult Increment(Counter counter)
    {
        counter.Count++;
        return View(counter);
    }
}

查看：

<form action="/test/increment" method="post">
    <input type="text" name="Count" value="<%= Model.Count %>" />
    <input type="submit" value="Submit" /> 
</form>

点击提交，我得到这样的值：

Clicking Submit I get such values:

5，6，7，8，...

使用Html.TextBox我预料的一样的行为

With Html.TextBox I expected the same behaviour

<form action="/test/increment" method="post">
    <%= Html.TextBox("Count") %>
    <input type="submit" value="Submit" /> 
</form>

但实际上得到了

5，5，5，5

这似乎Html.TextBox使用替代型号Request.Params？

It seems Html.TextBox uses Request.Params instead of Model?

推荐答案

Html.TextBox（）内部使用ViewData.Eval（）方法首先试图从字典中ViewData.ModelState旁边的值来检索值所述ViewData.Model的属性。这样做是为了让恢复无效的表格后，输入的数值提交。

Html.TextBox() uses internally ViewData.Eval() method which first attempts to retrieve a value from the dictionary ViewData.ModelState and next to retrieve the value from a property of the ViewData.Model. This is done to allow restoring entered values after invalid form submit.

从ViewData.ModelState字典中删除计数值帮助：

Removing Count value from ViewData.ModelState dictionary helps:

public ActionResult Increment(Counter counter)
{
    counter.Count++;
    ViewData.ModelState.Remove("Count");
    return View(counter);
}

另一种解决方案是使对GET两种不同的控制器方法和POST操作

Another solution is to make two different controller methods for GET and POST operations:

public ActionResult Increment(int? count)
{
    Counter counter = new Counter();

    if (count != null)
        counter.Count = count.Value;

    return View("Increment", counter);
}

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Increment(Counter counter)
{
    counter.Count++;

    return RedirectToAction("Increment", counter);
}

计数器对象还可以通过TempData的字典过去了。

Counter object could also be passed via TempData dictionary.

您还可能有兴趣的文章Repopulate表单域ViewData.Eval（）由斯蒂芬·瓦尔特的。

You may also be interested in the article Repopulate Form Fields with ViewData.Eval() by Stephen Walther.

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