Asp.net mvc 4 如何使用辅助方法有条件地输出视图的一部分

假设我有以下观点：

<td>
    @Html.ActionLink("Delete")
</td>

重载版本：

<td>
    @Html.ActionLink("Delete", "Delete", Permissions.DeleteItems)
</td>

然而，

BeginForm

——它实际上并没有对括号中的视图片段做任何处理。是否有方法使用帮助器删除括号内的标记

@using(Html.ShowIf(...))
{
    ...
}

---

是的，你可以。下面是一个仅适用于

Razor

的示例：

@using (this.BeginPermissionScope(Permissions.DeleteItems))
{
    using (Html.BeginForm("Delete", "Home"))
    {
        <input type="submit" value="Submit" />
    }
}

---

您的意思是使用

BeginForm

或使用（Html.yourheloper（））{…}之类的帮助程序删除括号内的标记？@渐近错误：使用（…）之类的帮助程序-我将进行编辑以澄清。很好，我正在编写一个示例来完成类似的操作。

@using(Html.BeginForm(...))
{
    ...
}

@using(Html.ShowIf(...))
{
    ...
}

@using (this.BeginPermissionScope(Permissions.DeleteItems))
{
    using (Html.BeginForm("Delete", "Home"))
    {
        <input type="submit" value="Submit" />
    }
}

public static class HtmlHelperPermissionScopeExtensions
{
    /// <summary>
    /// Begin new rendering scope based on current user permissions
    /// </summary>
    public static IDisposable BeginPermissionScope(this WebViewPage webViewPage, Permissions permission)
    {
        var currentIdentity = webViewPage.User.Identity;
        bool userHasPermission = currentIdentity.HasPermission(permission);
        return new PermissionScopeHelper(webViewPage, !userHasPermission);
    }

    /// <summary>
    /// Helper class that replaces current output stream with its own
    /// </summary>
    private sealed class PermissionScopeHelper : IDisposable
    {
        WebViewPage webViewPage;
        TextWriter oldWriter;
        TextWriter newWriter;

        /// <summary>
        /// Initializes helper class instance. If ignoreMarkupUntilDispose is set to true, then 
        /// all markup writen to response will be ignored
        /// </summary>
        public PermissionScopeHelper(WebViewPage page, bool ignoreMarkupUntilDispose)
        {
            if (ignoreMarkupUntilDispose)
            {
                webViewPage = page;
                newWriter = new StringWriter();

                // Replace output TextWriter for Write() and WriteLiteral() methods
                webViewPage.OutputStack.Push(newWriter);

                // Replace output TextWriter for all HtmlHelper and AjaxHelper extensions
                oldWriter = webViewPage.ViewContext.Writer;
                webViewPage.ViewContext.Writer = newWriter;
            }
        }

        /// <summary>
        /// Restore output TextWriters
        /// </summary>
        public void Dispose()
        {
            if (webViewPage != null)
            {
                webViewPage.ViewContext.Writer = oldWriter;
                webViewPage.OutputStack.Pop();
                newWriter.Dispose();
            }
        }
    }

}