ASP.NET MVC:Razor 中的自定义 Html Helpers [英] ASP.NET MVC: Custom Html Helpers in Razor

问题描述

与 Razor 一起使用时，我在使用 Html Helpers 时遇到困难.所述助手在带有 Web 表单视图引擎的 MVC 2 中运行良好.但不是在剃刀里.我在运行时得到的错误是:

I am having difficulty with Html Helpers when used with Razor. Said helpers worked fine in MVC 2 with the web form view engine. But not in razor. The error I get at runtime is:

Compiler Error Message: CS1502: The best overloaded method match for 'System.Web.WebPages.WebPageExecutingBase.Write(System.Web.WebPages.HelperResult)' has some invalid arguments

Source Error:


Line 1:  @using Wingspan.Web.Mvc;
Line 2:  @Html.IncrementalMenu(MenuBlock.Site)

展开显示详细的编译器输出显示:

Expanding the Show Detailed Compiler Output reveals:

d:...ViewsSharedMenuTop.cshtml(2,1): error CS1502: The best overloaded method match for 'System.Web.WebPages.WebPageExecutingBase.Write(System.Web.WebPages.HelperResult)' has some invalid arguments
d:...ViewsSharedMenuTop.cshtml(2,7): error CS1503: Argument 1: cannot convert from 'void' to 'System.Web.WebPages.HelperResult'

这向我表明 razor 不喜欢我的助手 IncrementalMenu 返回 void(在 MVC 2 Web 表单引擎视图中工作正常).

That indicates to me that razor doesn't like my helper, IncrementalMenu, returning void (which works fine in MVC 2 web form engine views).

我在编译时没有遇到错误，尽管代码行 (@Html.IncrementalMenu(...)) 是红色下划线并带有以下消息:

I get no errors at Compile time, although the line of code (@Html.IncrementalMenu(...)) is red underlined with the following message:

Cannot implicitly convert type 'void' to 'object'

IncrementalMenu 位于 Wingspan.Web.Mvc 命名空间中.其签名如下:

IncrementalMenu is in the Wingspan.Web.Mvc namespace. It's signature is as follows:

public static void IncrementalMenu(this HtmlHelper html, MenuBlock menuBlock)
{
    // Uses an HtmlTextWriter to render a menu from the sitemap
}

如果我知道出了什么问题，我会很生气...

I'm blowed if I know what is wrong...

附注:

MenuBlock 参数只是一个枚举，用于标识菜单应如何呈现.不要专注于此，因为那很好.

The MenuBlock parameter is just an enum that identifies how the menu should render. Don't fixate on this as that is fine.

推荐答案

你可以这样调用你的助手:

You can call your helper like this:

@{ Html.IncrementalMenu(MenuBlock.Site); }

WebForms 语法

WebForms syntax

<% Html.IncrementalMenu(MenuBlock.Site); %>

您只需调用您的方法，返回值(如果有)将被忽略.

You just call your method, and the return value (if there is any) is ignored.

像这样的代码需要一个返回值，并将返回值写入 html 流:

Code like this expects a return value, and writes the return value to the html stream:

@Html.YourHelper()

网络表单语法:

<%: Html.YourHelper() %>

相同，如果结果值 != IHtmlString:

The same, if result value != IHtmlString:

<%= Server.HtmlEncode(Html.YourHelper()) %>

这篇关于ASP.NET MVC:Razor 中的自定义 Html Helpers的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！