从类型'System.String'的参数转换为键入'T'失败，因为没有类型转换器可以将这些类型之间的转换

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问题描述

注意：所有code这里转述为例，作为我不能显示真正的code

NOTE: All of the code here is paraphrased as an example, as I can't show real code.

我有一个看起来像

public SearchViewModel
{
   public string Term
   {
     get; set;
   }

   public SearchResult Result
   {
     get; set;
   }

   public List<Filter> Filters
   {
     get; set;
   }
}

这势必会定期控制器，一切工作正常：

This is bound to a regular controller and everything works fine:

 public ActionResult Search (SearchViewModel model)
 {
      if (ModelState.IsValid)
      {
           model.Result = _searchService.Search(model.Term);
           return View(model);
      }
 }

我也有一个处理一个POST从包含复选框形式采取其他操作。该控制器用来处理创建过滤器类和重定向到搜寻行动。

I also have another action that handles taking in a POST from a form that contains checkboxes. This controller handles creating Filter classes and redirects to the Search action.

是这样的：

    public ActionResult Filter(FormCollection formParams)
    {
        return RedirectToAction("Search", new SearchViewModel
        {
            Term = formParams["Term"],
            Filters = 
                formParams.Keys
                    .Cast<String>()
                    .Where(k => k.Contains("filter"))
                    .Select(k => Filter.Build(k, formParams[k]))
                    .ToList()                        
        });                                        
    }

这传递与List集合填充回搜寻行动的视图模型。

This passes a ViewModel with the List collection populated back to the Search action.

然而，在搜索行动，ModelState.IsValid现在返回false。这是因为模型绑定抛出此异常：

However, in the search action, ModelState.IsValid now returns false. This is because the model binder throws this exception:

这类型的参数转换
  'System.String'输入'过滤器'
  失败，因为没有类型转换器可
  这些类型之间的转换。

综观ModelState中的过滤器节目的原始值是一个字符串：

Looking at the raw value in ModelState for "Filters" shows that is a string:

   System.Collections.Generic.List`1[Filter]

这似乎是表的实际内容动作之间的过渡过程中丢失，可能是因为它只是呼吁财产成员的ToString（）。

It seems like the actual contents of the List is lost during the transition between actions, likely because it only called ToString() on the property members.

在这一点上，我为什么失败的一个模糊的概念，和我的数字，但是我可以写一个自定义的模型绑定或类型转换器，使其工作，我有一种感觉，这种做法的气味，这是大概的东西是小事，我只是接近它错了。

At this point, I have a vague idea of why this is failing, and I figure I could write a custom model binder or type converters to make it work, however, I have a feeling that this approach smells, and this is probably something that is trivial, I'm just approaching it wrong.

那么，什么是正确的ASP.NET MVC 3，从一个动作传递复杂类型的集合到另一个？

So, what is the proper ASP.NET MVC 3 to pass a collection of complex types from one action to another?

类型

从类型'System.String'的参数转换为键入'T'失败，因为没有类型转换器可以将这些类型之间的转换

问题描述

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