你是说内联helper?

@helper SayHello(string name)
{
    <div>Hello @name</div>
}

@SayHello("John")

先不讨论什么时候(如果有的话)应该做这件事，@functions就是你做这件事的方式。

@functions {

    // Add code here.

}

Razor只是一个模板引擎。

您应该创建一个常规类。

如果你想在Razor页面中创建一个方法，把它们放在@functions块中。

你也可以用Func这样做

@{
    var getStyle = new Func<int, int, string>((width, margin) => string.Format("width: {0}px; margin: {1}px;", width, margin));
}

<div style="@getStyle(50, 2)"></div>

在razor中定义一个函数非常简单。

@functions {

    public static HtmlString OrderedList(IEnumerable<string> items)
    { }
}

你可以在任何地方调用函数。就像

@Functions.OrderedList(new[] { "Blue", "Red", "Green" })

但是，同样的工作也可以通过helper完成。举个例子

@helper OrderedList(IEnumerable<string> items){
    <ol>
        @foreach(var item in items){
            <li>@item</li>
        }
    </ol>
}

So what is the difference?? According to this previous post both @helpers and @functions do share one thing in common - they make code reuse a possibility within Web Pages. They also share another thing in common - they look the same at first glance, which is what might cause a bit of confusion about their roles. However, they are not the same. In essence, a helper is a reusable snippet of Razor sytnax exposed as a method, and is intended for rendering HTML to the browser, whereas a function is static utility method that can be called from anywhere within your Web Pages application. The return type for a helper is always HelperResult, whereas the return type for a function is whatever you want it to be.

你也可以使用@{}块来创建函数:

@{
    async Task<string> MyAsyncString(string input)
    {
        return Task.FromResult(input);
    }
}

然后在你的剃须刀页后面:

   <div>@(await MyAsyncString("weee").ConfigureAwait(false))</div>

MyModelVm.cs

public class MyModelVm
{
    public HttpStatusCode StatusCode { get; set; }
}

Index.cshtml

@model MyNamespace.MyModelVm
@functions
{
    string GetErrorMessage()
    {
        var isNotFound = Model.StatusCode == HttpStatusCode.NotFound;
        string errorMessage;
        if (isNotFound)
        {
            errorMessage = Resources.NotFoundMessage;
        }
        else
        {
            errorMessage = Resources.GeneralErrorMessage
        }

        return errorMessage;
    }
}

<div>
    @GetErrorMessage()
</div>

您也可以使用下面的代码块。它更干净，功能更丰富。你也可以在上面插入变量，在下面插入函数。而不是使用2个单独的代码块。

@{
    string exampleVariable = "just an example variable";
    string anotherExampleVariable = "just another example variable";

    string GetErrorMessage()
    {
        var isNotFound = Model.StatusCode == HttpStatusCode.NotFound;
        string errorMessage;
        if (isNotFound)
        {
            errorMessage = Resources.NotFoundMessage;
        }
        else
        {
            errorMessage = Resources.GeneralErrorMessage
        }

        return errorMessage;
    }
}

下面是如何在ASP中编写列表助手。NET Core 3

现在，您可以在代码块中声明的方法体中包含HTML标记，就像以前一样作为本地方法，或者在@functions块中包含HTML标记。方法应该返回 void，或者Task(如果需要异步处理):

@{
    void Template(string[] listItems, string style)
    {
        <ul>
            @foreach (var listItem in listItems)
            {
            <li class="@style">@listItem</li>
            }
        </ul>
    }
}