請問 在範例中【String[] listUnpaged = sampleData.Split('\n');】
為什麼可以用【listUnpaged.ToPagedList(page ?? 1, pageSize);】

而我寫的練習中
為什麼不可以用【datas.ToPagedList(page ?? 1, pageSize);】
這個用法叫什麼?

範例Controller

...略...
const int pageSize = 20;
// retrieve list from database/whereverand
string sampleData = new StreamReader(Server.MapPath("~/App_Data/Names.txt")).ReadToEnd();
String[] listUnpaged = sampleData.Split('\n');
 // page the list
var listPaged = listUnpaged.ToPagedList(page ?? 1, pageSize);

練習Controller

...略...
const int pageSize = 20;
// retrieve list from database/whereverand
List<ITAccountModel> datas = com.WEB.ViewModel.DemoVM.Test.TestDatas;
 // page the list
var listPaged = X.PagedList.PagedListExtensions.ToPagedList(datas,page ?? 1, pageSize);

X.PagedList.PagedListExtensions.ToPagedList

namespace X.PagedList
{
public static class PagedListExtensions
{
	...略...
	[AsyncStateMachine(typeof(PagedListExtensions.<ToListAsync>d__7<>))]
	public static Task<List<T>> ToListAsync<T>(this IEnumerable<T> superset);
	public static IPagedList<T> ToPagedList<T>(this IEnumerable<T> superset, int pageNumber, int pageSize);
	public static IPagedList<T> ToPagedList<T>(this IEnumerable<T> superset);
	public static IPagedList<T> ToPagedList<T, TKey>(this IQueryable<T> superset, Expression<Func<T, TKey>> keySelector, int pageNumber, int pageSize);
	public static IPagedList<T> ToPagedList<T, TKey>(this IEnumerable<T> superset, Expression<Func<T, TKey>> keySelector, int pageNumber, int pageSize);
	...略...
}
}