IEnumerable - foreach - 查询的结果不能多​​次枚举

Question

我有以下代码:

public static string ConvertParamToHTMLString(
                            IEnumerable<GetParm_Result> paramList)
{
    foreach (GetParm_Result result in paramList.ToList())
    {
      ...
      ...
    }
}

我尝试执行foreach时收到以下消息:

查询的结果不能多​​次枚举.

我以为ToList()会解决这个问题..

Answer 1

调用paramList.ToList()一次并将其放入变量中,然后枚举变量:

var list = paramList.ToList();
foreach(var result in list) ...
foreach(var result in list) ...   // No error here