爲什麼需要解析？

Question

我有問題關於HTML輔助解析：

我也有東西喜歡：

@foreach (var item in ViewBag.News) 
{ 
    @Html.ActionLink(item.gdt_title, "News", "News", new { lang = ViewBag.Lang, page = ViewBag.CurrentPage, id = item.gdt_id }, null) 
} 

所以後來我有一個錯誤：

'System.Web.Mvc.HtmlHelper<dynamic>' has no applicable method named 'ActionLink' but appears to have an extension method by that name. Extension methods cannot be dynamically dispatched. Consider casting the dynamic arguments or calling the extension method without the extension method syntax.

我manualy解析解決它第一與字符串相關的參數：

@foreach (var item in ViewBag.News) 
{ 
    @Html.ActionLink((String)item.gdt_title, "News", "News", new { lang = ViewBag.Lang, page = ViewBag.CurrentPage, id = item.gdt_id }, null) 
} 

但我不知道爲什麼會發生。

有人可以解釋嗎？

Answer 1

使用ViewBag/ViewData是不好的做法。

您正在使用動態模型，並且item.gdt_title是動態的。如例外情況所述，

Extension methods cannot be dynamically dispatched

您應該使用強類型視圖模型。這樣

public class NewsViewModel 
{ 
    public string Lang { get; set; } 
    public int CurrentPage { get; set; } 
    public List<NewsItem> News { get; set; } 
} 

public class NewsItem 
{ 
    public string gdt_id { get; set; } 
    public string gdt_title { get; set; } 
} 

控制器東西

public ActionResult News() 
{ 
    NewsViewModel news = new NewsViewModel(); 
    news.News = LoadNews(); 

    return View(news); 
} 

視圖

@model NewsViewModel 

@foreach (var item in Model.News) 
{ 
    @Html.ActionLink(item.gdt_title, "News", "News", new { lang = Model.Lang, page = Model.CurrentPage, id = item.gdt_id }, null) 
}