有谁知道为什么我会收到这个 asp.net 错误？CS1061 linqtotwitter

Question

使用linqtotwitter，我试图搜索推文，并使用以下模型在表中显示它们：

using System;
using System.ComponentModel;

namespace test.Models
{
public class TweetSearchModel
{
[DisplayName("Tweet ID")]
public ulong ID { get; set; }
[DisplayName("Screen Name")]
public string ScreenName { get; set; }
[DisplayName("Tweet")]
public string Text { get; set; }
internal object ToListAsync()
{
throw new NotImplementedException();
}
}
}

此视图：

@model IEnumerable<test.Models.TweetSearchModel>
@{
ViewBag.Title = "Search";
}
<table>
@foreach (var item in Model)
{
<tr>
<td>
@Html.DisplayFor(modelItem => item.ID)
</td>
<td>
@Html.DisplayFor(modelItem => item.ScreenName)
</td>
<td>
@Html.DisplayFor(modelItem => item.Text)
</td>
</tr>
}
</table>

这个控制器：

using System;
using System.Linq;
using System.Threading.Tasks;
using System.Web.Mvc;
using aLevel.Models;
using LinqToTwitter;
using System.Collections.Generic.I;
using System.Data.Entity;
namespace test.Controllers
{
public class QueriesController : Controller
{
// GET: Queries
public ActionResult Index()
{
return View();
}
[ActionName("Search")]
public async Task<ActionResult> SearchAsync()
{
var auth = new MvcAuthorizer
{
CredentialStore = new SessionStateCredentialStore()
};
var ctx = new TwitterContext(auth);
var searchResponse =
await
(from search in ctx.Search
where search.Type == SearchType.Search &&
search.Query == ""LINQ to Twitter""
select search)
.SingleOrDefaultAsync();
var tweets =
await
(from tweet in searchResponse.Statuses
select new TweetSearchModel
{
ID = tweet.ID,
ScreenName = tweet.ScreenName,
Text = tweet.Text
})
.ToListAsync();
return View(tweets);
}
}
}

但是，".ToListAsync"正在抛出错误"CS1061'IEnumerable'不包含'ToListAsync'的定义，并且找不到接受'IEnumarable'类型的第一个参数的扩展方法'ToList异步'(是否缺少using指令或程序集引用？(">

Answer 1

searchResponse.Statuses是List<Status>，因此您正在执行LINQ to Objects查询。LINQ to Objects(Enumerable(没有ToListAsync，我不确定它应该有，因为查询不会导致进程外操作——它只在内存中。您可以使用非异步运算符，如以下所示：

var tweets =
(from tweet in searchResponse.Statuses
select new TweetSearchModel
{
ID = tweet.ID,
ScreenName = tweet.ScreenName,
Text = tweet.Text
})
.ToList();

Answer 2

ToListAsync是一个带有参数cancellationToken的扩展方法，请参阅https://msdn.microsoft.com/de-de/library/dn220261.aspx.因此，您需要向参数cancellationToken传递一个值以消除编译器错误。