如何在html.dropdownlist（mcv5）中绑定嵌套对象 [英] How to bind a nested object in a html.dropdownlist (mcv5)

问题描述

我有3个班级。



人，地址，国家。



人数n：1地址

地址n：1国家。



我的EF型号工作正常但是......



当我使用脚手架生成我的地址视图时，它可以工作。



和



当我使用脚手架生成我的Person并手动添加地址字段时。



下拉列表无效。



当我在debugmode中检查我的模型时，CountryId = 0.



我该怎么办？



srry如果我的englitch是可怕的坏我有点noobie

< div class = 形式的基团 > 
 @ Html.LabelFor（model => model.Address.IdCountry，IdCountry，htmlAttributes：new {@class =control-label col-md-2}）
< div class = COL-MD-10 > 
 @ Html.DropDownList（IdCountry，null，htmlAttributes：new {@class =form-control}）
 @ Html.ValidationMessageFor（model => model.Address.IdCountry， ，new {@class =text-danger}）
< / div> 
< / div> 

解决方案

好的，CountryId是0，因为这是int值的默认值（或者它应该是IdCountry，就像你的代码中所示）。



你想要使用一个稍微不同的辅助类，Html.DropDownListFor（ ）。它应该如下所示：

 @ Html.DropDownListFor（model = >  model.IdCountry，Model.mySelectListItems， new  {@class =  表单控件}）

现在，您需要进行一些更改在模型方面。由于我不知道你的型号名称，我只称它为ViewModel：

  public   class  ViewModel 
 {
 ... 
  public  IEnumerable< selectlistitem> mySelectListItems 
 ... 
} 
 < /   selectlistitem  < span class =code-keyword>>  

最后，因为我不知道你怎么样重新构建ViewModel，我们将看一下基于控制器的实现：

  public  ActionResult MyViewAction（）
 {
 ... 
  //  创建ViewModel对象后 
 ViewModelInstance.mySelectListItems = 
 MyDbContext.Countries.Select（x = >  
  new  SelectListItem {
 Value = x.Id，
 Text = x.Name 
}）。ToArray（）; 
 ... 
} 

有一个相当全面的演练：

使用ASP.NET MVC的DropDownListFor [ ^ ]

i have 3 classes.

Person, Address, Country.

Person n:1 Address
Address n:1 Country.

my EF model is working correctly but...

when i use scaffolding to generate my Address views it works.

and

when i use scaffolding to generate my Person and manually add the address fields.

the dropdownlist doesnt work.

when i check my model in debugmode, the CountryId is = 0.

what can i do?

srry if my englitch is terrible bad im a little noobie

<div class="form-group">
    @Html.LabelFor(model => model.Address.IdCountry, "IdCountry", htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
        @Html.DropDownList("IdCountry", null, htmlAttributes: new { @class = "form-control" })
        @Html.ValidationMessageFor(model => model.Address.IdCountry, "", new { @class = "text-danger" })
     </div>
</div>

解决方案

Okay, CountryId is coming through as 0 since that's the default value for an int value (or is it supposed to be IdCountry, as that's shown in your code).

You'll want to use a slightly different helper class, the Html.DropDownListFor(). It should look like this:

@Html.DropDownListFor(model => model.IdCountry, Model.mySelectListItems, new { @class = "form-control" })

Now, you'll need to make a couple of changes on the model side. Since I don't know your model name, I'll just call it ViewModel:

public class ViewModel
{
   ...
   public IEnumerable<selectlistitem> mySelectListItems
   ...
}
</selectlistitem>

And finally, since I don't know how you're building your ViewModel, we'll look at a controller-based implementation:

public ActionResult MyViewAction()
{
   ...
   // After the ViewModel object has been created
   ViewModelInstance.mySelectListItems = 
      MyDbContext.Countries.Select(x => 
         new SelectListItem { 
            Value = x.Id, 
            Text = x.Name 
      }).ToArray();
   ...
}

There is a fairly comprehensive walkthrough at:
DropDownListFor with ASP.NET MVC[^]

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