当我的模型为null时，如何避免View的foreach循环中出现NullReferenceException? [英] How does one avoid a NullReferenceException in a foreach loop within a View when my model is null?

问题描述

当我通过控制器传递null值时，在我的View中出现以下代码，出现"NullReferenceException未由用户代码处理"错误.在某些情况下，我想传递一个空值，但是在发生这种情况时，我不希望引发错误.我应该将代码更改为什么?

I get a "NullReferenceException was unhandled by user code" error with the following code in my View when I pass in a null value via my controller. There are situations where I want to pass in a null value, but I do not want an error thrown when this happens. What should I change my code to?

最初我的代码是:

@foreach (var item in Model.MyModelStuff)
{
    <tr>
        <td>
                @Html.DisplayFor(modelItem => item.Bla.Title)
        </td>
    <tr>
}

我尝试了以下失败的尝试:

I have tried the following with no success:

@foreach (var item in Model.MyModelStuff.Where( item => item.MyModelStuff != null))
etc. . . 

如何更改代码，使其在不引发错误的情况下处理null?我已经读过我可能需要返回模型的空集合(?)，如果确实需要这样做，我将如何去做?

How do I change the code so that it will handle null without throwing an error? I've read I may need to be returning an empty collection of my model (?), how would I go about doing that - if it is indeed the necessary thing to do?

推荐答案

如果我的理解正确，则您的收藏集为空.

If my understanding is correct your collection is null.

集合永远不能为空，就像您说过的那样，您应该返回一个空集合，并防止您的集合被破坏而不暴露真实集合:

A collection should never be null, like you said you should return an empty collection instead and prevent your collection to be corrupted not exposing the real collection:

public IList<Employee> Employees
{
    get; 
    private set;
}

并在构造函数中初始化您的集合

And initialize your collection inside the constructor

this.Employees = new List<Employee>();

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