razor 中的嵌套 for 循环

发布于 2025-01-07 20:49:53 字数 589 浏览 0 评论 0原文

我有一个带有 Razor 的 ASP.Net MVC 应用程序。我尝试访问视图中的集合。这是我的代码：

@foreach (var question in ViewBag.Questions) {
    <p>@question.Name</p>

    foreach (var answer in question.Answers) {
        <input type="radio" name="@answer.QuestionId" value='@answer.id' /> @answer.Text<br />
    }
}

在 foreach (var answer in question.Answers) 我得到：

“ObjectContext 实例已被释放，不能再用于需要连接的操作。”

对于 Questions 集合，我有一个 .ToList()，但是如果我想访问 ti，我该如何处理 Answers 集合？在运行时？

原文

I have a ASP.Net MVC app with Razor. I try to access a collection in the view. Here is my code:

@foreach (var question in ViewBag.Questions) {
    <p>@question.Name</p>

    foreach (var answer in question.Answers) {
        <input type="radio" name="@answer.QuestionId" value='@answer.id' /> @answer.Text<br />
    }
}

At foreach (var answer in question.Answers) I get:

"The ObjectContext instance has been disposed and can no longer be used for operations that require a connection."

I have a .ToList() when it comes to the Questions collection but what do I do with the Answers collection if I want to access ti at runtime?

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我不在是我 2025-01-14 20:49:53

确保您已在控制器中急切地加载了 Answers 集合：

public ActionResult Foo()
{
    ViewBag.Questions = db.Questions.Include("Answers").ToList();
    return View();
}

关于 ViewBag，您可以使用视图模型来代替。更不用说您的问题纯粹与您正在使用的数据访问技术（我想是 EntityFramework）有关，与 ASP.NET MVC 无关。

Make sure you have eagerly loaded the Answers collection in your controller:

public ActionResult Foo()
{
    ViewBag.Questions = db.Questions.Include("Answers").ToList();
    return View();
}

And concerning ViewBag, well, you could have used a view model instead. Not to mention that your problem is purely related to the data access technology you are using (I suppose EntityFramework) and has nothing to do with ASP.NET MVC.

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