MVC Html.DisplayFor用于派生模型的列表 [英] MVC Html.DisplayFor for Lists of Derived Models

问题描述

让我们假设我有三个类: Derived1ViewModel ， Derived2ViewModel 和 BaseViewModel ，它们是 Derived1ViewModel 的超类代码>和 Derived2ViewModel .

Let's assume that I have three classes: Derived1ViewModel, Derived2ViewModel and BaseViewModel which serves as a superclass for the Derived1ViewModel and Derived2ViewModel.

我有一个DisplayTemplate，它具有 List< BaseViewModel> 作为模型，我想从使用 List< Derived1ViewModel>作为模型的视图中调用此模板或 List<Derived2ViewModel> .

I have a DisplayTemplate which has as a model a List<BaseViewModel> and I would like to call this template from views which are using as a model a List<Derived1ViewModel> or a List< Derived2ViewModel>.

如果我尝试执行此操作，则会触发异常，说它无法将 List< Derived1ViewModel> 或 List< Derived2VIewModel> 转换为 List<BaseViewModel>.如果我尝试应用诸如 @ Html.DisplayFor(model => model.Cast< BaseViewModel> .ToList()，"MyTemplate")之类的强制转换，则InvalidOperationException是抛出.

If I try to do this, an exception is triggered saying that it cannot convert a List<Derived1ViewModel> or List<Derived2VIewModel> to a List<BaseViewModel>. If I try to apply a cast such as @Html.DisplayFor(model=>model.Cast<BaseViewModel>.ToList(), "MyTemplate") an InvalidOperationException is thrown.

详细信息:[InvalidOperationException:模板只能与字段访问，属性访问，一维数组索引或单参数自定义索引器表达式一起使用.]

Details: [InvalidOperationException: Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.]

这个问题可以解决吗，还是采取另一种方法所必需的?

Can this problem be solved or its necessary to take another approach?

推荐答案

通过使用 BaseViewModel 的模板而不是 List< BaseViewModel> 的模板解决了该问题.这样，我可以将任何派生类型传递给模板(例如:Derived1ViewModel，Derived2ViewModel).

Solved the problem by using a template for BaseViewModel instead of List<BaseViewModel>. In this way, I can pass any derived type to the template (ex: Derived1ViewModel, Derived2ViewModel).

示例:

@*Derived1 View*@
@model List<Derived1ViewModel>
@for(var i = 0; i < Model.Count; i++)
{
    int i1 = i;
    @Html.DisplayFor(model=>model[i1], "MyTemplate")
}

@*Derived2 View*@
@model List<Derived2ViewModel>
@for(var i = 0; i < Model.Count; i++)
{
    int i1 = i;
    @Html.DisplayFor(model=>model[i1], "MyTemplate")
}

@*Template*@
@model BaseViewModel
<p>It works @Model.Name</p>

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