如何在Task.Run中调用异步方法? [英] How to call Async Method within Task.Run?

问题描述

我需要以异步方式发送邮件.我已经弄清楚了要使用Razor Generator从razor视图生成HTML模板.现在我需要使用SmtpClient.SendMailAsync将HTML作为邮件发送.但是我发现Razor生成器要花很多时间，并且我不想在我的send mail方法中包括模板生成部分，因为send mail方法应该不关心获取HTML模板.

I need to send mail in Async way. I have figured out to use Razor Generator to generate Html template from razor view. now i need to use SmtpClient.SendMailAsync to send the html as Mail. but i found Razor generator takes quite some time and i do not want to include the template generation part inside my send mail method as the send mail method should not be concerned about getting the Html Template.

我有示例代码:

public static void SendEmailAsync<TModel>(TModel model, string templatePath, string subj, string toEmail, string cc = null, string bcc = null)
    {

        string templateFilePath = HostingEnvironment.MapPath(templatePath);
        // Generate the email body from the template file.
        // 'templateFilePath' should contain the absolute path of your template file.
        if (templateFilePath != null)
        {
            Task.Run(() =>
            {
                var emailHtmlBody = Engine.Razor.RunCompile(File.ReadAllText(templateFilePath),
                templateFilePath, model.GetType(), model);
                SendEmailAsync(subj, emailHtmlBody, toEmail, cc, bcc);
            });
        }
        else
        {
            throw new System.Exception("Could not find mail template.");
        }
    }

，SendMailAsync的签名为:

and the signature for SendMailAsync Is:

static async Task SendEmailAsync(string subj, string message, string toEmail, string cc = null, string bcc = null)
    {
        //Reading sender Email credential from web.config file  
        string fromEmail = ConfigurationManager.AppSettings["FromEmail"].ToString();
        string fromName = ConfigurationManager.AppSettings["FromName"].ToString();

        //creating the object of MailMessage  
        MailMessage mailMessage = new MailMessage();
        mailMessage.From = new MailAddress(fromEmail, fromName); //From Email Id  
        mailMessage.Subject = subj; //Subject of Email  
        mailMessage.Body = message; //body or message of Email  
        mailMessage.IsBodyHtml = true;

        string[] toMuliId = toEmail.Split(',');
        foreach (string toEMailId in toMuliId)
        {
            mailMessage.To.Add(new MailAddress(toEMailId)); //adding multiple TO Email Id  
        }


        if (cc != null)
        {
            string[] ccId = cc.Split(',');

            foreach (string ccEmail in ccId)
            {
                mailMessage.CC.Add(new MailAddress(ccEmail)); //Adding Multiple CC email Id  
            }
        }

        if (bcc != null)
        {
            string[] bccid = bcc.Split(',');

            foreach (string bccEmailId in bccid)
            {
                mailMessage.Bcc.Add(new MailAddress(bccEmailId)); //Adding Multiple BCC email Id  
            }
        }

        SmtpClient smtp = new SmtpClient
        {
            EnableSsl = true,
            Credentials = new NetworkCredential("", "")
        };

        //network and security related credentials  
        await smtp.SendMailAsync(mailMessage); //sending Email  
    }

没有引发异常，但我得到了错误:

No exceptions are thrown but i get the error:

System.InvalidOperationException:此时无法启动异步操作.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中的某些事件期间启动.如果在执行页面时发生此异常，请确保该页面被标记为<％@ Page Async ="true"％>.此异常也可能表示尝试调用异步无效"方法，ASP.NET请求处理通常不支持该方法.相反，异步方法应该返回一个Task，而调用者应该等待它.

System.InvalidOperationException: An asynchronous operation cannot be started at this time. Asynchronous operations may only be started within an asynchronous handler or module or during certain events in the Page lifecycle. If this exception occurred while executing a Page, ensure that the Page is marked <%@ Page Async="true" %>. This exception may also indicate an attempt to call an "async void" method, which is generally unsupported within ASP.NET request processing. Instead, the asynchronous method should return a Task, and the caller should await it.

推荐答案

使用此:

await Task.Run(async () =>
{
    await DoAsyncMethodAsync();
});

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