C#：此时无法启动异步操作。

Question

我正在尝试在ASP Web表单中单击提交按钮时运行我的代码。当我单击按钮时，错误就会发生。有人知道原因吗？错误消息显示如下：

应用程序'/'中的服务器错误。

无法在此时启动异步操作。异步操作只能在异步处理程序或模块内或在页面生命周期的某些事件期间启动。如果在执行页面时发生此异常，请确保该页面已标记为<%@ Page Async="true" %>。

aspx文件：

<asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server">
<div class="jumbotron">
    <h1>Luis</h1>        
        <asp:TextBox ID="TextBox1" runat="server" Height="40px" Width="273px"></asp:TextBox>    
</div>
    <p>
       <input id="Submit1"  runat="server" type="submit" value="Check" onserverclick="Submit_Click"/></p>  
    <p>
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</p>
</asp:Content>

.cs文件：

public partial class _Default : Page
{
public async void Submit1_Click(object sender, EventArgs e) {

    string utterance = TextBox1.Text;

    var client = new HttpClient();
    var queryString = HttpUtility.ParseQueryString(string.Empty);

    // This app ID is for a public sample app that recognizes requests to turn on and turn off lights
    var luisAppId = "75bcaaff-1dc1-4dsa-adf7-63584cea339a";
    var subscriptionKey = "43314f19c5ecgdascba6a00f1d3cc3533";

    // The request header contains your subscription key
    client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", subscriptionKey);

    // The "q" parameter contains the utterance to send to LUIS
    //queryString["q"] = "turn on the left light";

    // These optional request parameters are set to their default values
    queryString["timezoneOffset"] = "0";
    queryString["verbose"] = "false";
    queryString["spellCheck"] = "false";
    queryString["staging"] = "false";

    var uri = "https://westus.api.cognitive.microsoft.com/luis/v2.0/apps/" + luisAppId + "?" + queryString + "&q=" + utterance;
    var response = await client.GetAsync(uri);

    var strResponseContent = await response.Content.ReadAsStringAsync();

    // Display the JSON result from LUIS
    //Console.WriteLine(strResponseContent.ToString());
    Label1.Text = strResponseContent.ToString();
}
}

- raspi surya

Answer 1

您正在调用一个ASYNC方法，但答案在错误信息中。

请确保页面已标记为<%@ Page Async="true" %>。

- Cody Popham