的WebGrid：无法转换lambda表达式中键入'对象'，因为它不是委托类型 [英] Webgrid: Cannot convert lambda expression to type 'object' because it is not a delegate type

问题描述

我试着在列的WebGrid与此代码添加一个HTML图片：

Im trying to add in the webgrid column an html image with this code:

@model List<LoUCore.Models.Artifact>
@{    
   var grid = new WebGrid(Model);
   List<WebGridColumn> column = new List<WebGridColumn>();
   column.Add(new WebGridColumn { ColumnName = "Filepath", Header = "Sprite",Format = (x => @<text><img src="@x.Filepath"></img></text>) });
 }
@grid.GetHtml(columns: grid.Columns(column.ToArray()))

但即时得到以下错误：

CS1660: Cannot convert lambda expression to type 'object' because it is not a delegate type

任何想法？

推荐答案

您不能使用lambda表达式中的嵌入式剃刀字符串，如@Alessandro D'安德拉意味着你必须使用 X => < IMG SRC ='+ someString +'>< / IMG>中。而不是

You can't use embedded razor strings within the lambda expression, as @Alessandro D'Andra suggests you have to use x => "<img src='" + someString + "'></img>"; instead.

您可能还把它包起来一切都在 MvcHtmlString 来防止剃刀逃逸字符串一旦使用格式化，但我不知道格式是如何工作的 - 你必须试试吧。

You might also have to wrap it all in an MvcHtmlString to prevent Razor from escaping the string once it is used by the formatter, but I don't know exactly how the formatter works - you have to try it.

我做了一个小测试文件，找出到底是什么剃刀编译器会与您的代码做的。这是剃刀文件：

I made a small test file to find out exactly what the Razor compiler would do with your code. This is the razor file:

@{
    string someString = "somestring";

    Func<object, object> a = x => "<text><img src='" + someString + "'></img></text>";
    Func<object, object> b = x => @<text><img src="@someString"></img></text>);  
}

在ASP.NET编译器创建此C＃代码出来的（只有相关的部分包括）：

The ASP.NET compiler creates this C# code out of it (only relevant parts included):

    string someString = "somestring";

    Func<object, object> a = x => "<text><img src='" + someString + "'></img></text>";
    Func<object, object> b = x => 

            #line default
            #line hidden
item => new System.Web.WebPages.HelperResult(__razor_template_writer => {

BeginContext(__razor_template_writer, "~/Views/Home/Index.cshtml", 210, 4, true);

WriteLiteralTo(__razor_template_writer, "<img");

EndContext(__razor_template_writer, "~/Views/Home/Index.cshtml", 210, 4, true);

WriteAttributeTo(__razor_template_writer, "src", Tuple.Create(" src=\"", 214), Tuple.Create("\"", 231)

            #line 7 "c:\temp\MvcApplication1\Views\Home\Index.cshtml"
, Tuple.Create(Tuple.Create("", 220), Tuple.Create<System.Object, System.Int32>(someString

            #line default
            #line hidden
, 220), false)
);

BeginContext(__razor_template_writer, "~/Views/Home/Index.cshtml", 232, 7, true);

WriteLiteralTo(__razor_template_writer, "></img>");

EndContext(__razor_template_writer, "~/Views/Home/Index.cshtml", 232, 7, true);

使用嵌入式文本语法 @<文本>在lambda表达式中创建显然是不正确的C＃代码。这是不足够的智慧使lambda表达式的嵌入式标签的一部分，而不是它打破通过插入代码来发出嵌入文本马上lambda表达式。

Using the embedded text syntax @<text> within the lambda expression creates obviously incorrect C# code. It is not smart enough to make the embedded tags part of the lambda expression, instead it breaks the lambda expression by inserting code to emit the embedded text right away.

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