模型包含多个对象视图模型绑定 [英] Model binding for a ViewModel containing multiple objects

问题描述

我有型ProductListingViewModel又包含一个ProductViewModel的强类型视图。 （包括自定义视图模型）。

I have a strongly typed view of type ProductListingViewModel which in turn contains a ProductViewModel. (both custom view models).

我有我的网页上某种形式的元素，这些都是像这样创建：

I have some form elements on my page and these are created like so:

<%: Html.DropDownListFor(m => m.ProductViewModel.CategoryId, Model.Categories)%>

在产生HTML：

which generates the HTML:

<select name="ProductViewModel.CategoryId" id="CategoryId">

使用默认的模型绑定我的预期，当我张贴到我控制器操作，它接受类型ProductListingViewModel的参数，它会知道的有关数据来填充ProductViewModel.CategoryId。

With the default model binding I expected that when I post to my controller action which accepts a parameter of type ProductListingViewModel, that it'd know to populate the ProductViewModel.CategoryId with the relevant data.

选择列表的名称似乎表明，它知道有一个的CategoryId属性ProductViewModel但是当我张贴到我控制器的方法，该ProductViewModel为空。如果我建ProductListingViewModel期间创建这个那么它不再为空，但默认联似乎并不如我想像的要填充的属性。

The name of the select list seems to indicate that it knows there's a ProductViewModel with a CategoryId property however when I post to my controller method, the ProductViewModel is null. If I create this during construction of the ProductListingViewModel then it's no longer null but the default binder doesn't seem to be populating the properties as I expected.

这是一个自定义模型粘结剂的情况下，还是我只是失去了一些东西根本？

Is this a case for a custom model binder or am I just missing something fundamental?

干杯。

推荐答案

让我试着总结（纠正我，如果我错了）。

Let me try to summarize (correct me if I am wrong).

型号：

public class ProductListingViewModel
{
    public ProductViewModel ProductViewModel { get; set; }
    public IEnumerable<SelectListItem> Categories { get; set; }
}

public class ProductViewModel
{
    public string CategoryId { get; set; }
}

控制器：

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var model = new ProductListingViewModel
        {
            Categories = new SelectList(new[]
            {
                new { Value = "1", Text = "category 1" },
                new { Value = "2", Text = "category 2" }
            }, "Value", "Text")
        };
        return View(model);
    }

    [HttpPost]
    public ActionResult Index(ProductListingViewModel model)
    {
        return View(model);
    }
}

查看：

<% using (Html.BeginForm()) { %>
    <%: Html.DropDownListFor(m => m.ProductViewModel.CategoryId, Model.Categories)%>
    <input type="submit" value="OK" />
<% } %>

现在，当您提交表单，您将得到：

Now when you submit the form you will get:

model.ProductViewModel.CategoryId = the id that was selected in the drop down list

是不是你所追求的？

Isn't what you are after?

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