c# - foreach 语句不能对“getenumerator”的公共定义类型的变量进行操作

Question

Task03Entities.Entites entities = new Task03Entities.Entites();

// Creat a object for my entites class
Task03BAL.BAL bal = new Task03BAL.BAL();

// creat a object of BAL to call Get Data Method
List<Task03Entities.Entites> entitiesList = new List<Task03Entities.Entites>();

// make a list of class Entities
entitiesList = bal.GetData(entities);

// store data in list
ViewState.Add("Products", entitiesList.ToArray());

// use view state to store entitieslist
Task03Entities.Entites[] entitiesArray =(Task03Entities.Entites[])ViewState["Products"];
List<Task03Entities.Entites> ViewStateList =new List<Task03Entities.Entites(entitiesArray);

// so now ViewStateList contain entitieslist data
// Now the Problem which i am facing is 
if (Request.QueryString["count"] != null) // this is okay
{
  listCount =Convert.ToInt32(Request.QueryString["count"]);   
}

for (int i = (listCount * 2)-2; i < listCount * 2; i++)
{
  Task03Entities.Entites newViewStateList = new Task03Entities.Entites();
  newViewStateList = ViewStateList[i];

// view state contain a list of data here on above line m trying to acess single data
%>
<table>
<%                  

foreach (Task03Entities.Entites item in newViewStateList)
// on above line i am getting following error message 

编译器错误消息：CS1579：foreach 语句无法对“Task03Entities.Entites”类型的变量进行操作，因为“Task03Entities.Entites”不包含“GetEnumerator”的公共定义

Answer 1

很简单：Task03Entities.Entites不是一个集合。

你在这里初始化一个对象：

Task03Entities.Entites newViewStateList = new Task03Entities.Entites();

然后尝试迭代它，就好像它是一个集合一样：

foreach (Task03Entities.Entites item in newViewStateList)
{

}

我怀疑你想要类似的东西：

List<Task03Entities.Entites> newViewStateList = new List<Task03Entities.Entites>();

foreach (Task03Entities.Entites item in newViewStateList)
{
    //code...
}

Answer 2

考虑到消息，您的类型 Task03Entities.Entites不是集合和/或不可枚举类型。所以为了能够使用foreach它，你必须让它成为这样。

例如可以看看：How to make a Visual C# class used in a foreach statement

Answer 3

只需在第一行添加 @model IEnumerable int 而不是常规的 @model 行