c# - Outlook ItemAdd 事件针对新日历项目触发两次

Question

我正在开发一个 Outlook 加载项，该加载项将监视当前用户的日历并在收到特定类型的约会或 session 时向该用户发送电子邮件。我们有一个第三方应用/服务正在向 Outlook 中的用户发送新的 session 请求，但不会向登录 Outlook 的用户发出任何通知。在我们更换第三方应用程序之前，我的加载项是一种解决方法，因此可以在发送此 session ​​请求时向用户发出提醒。

我使用 ItemAdd 事件来监视何时添加约会/ session (即从第三方应用程序发送)。我看到的是该事件触发两次(即使我只声明了处理程序一次):当从不同用户收到约会时一次，当从其他用户收到约会时一次当前用户已接受或暂时接受预约。

我只需要在第一次收到预约时触发它，而不是在接受预约时触发。我可以监视用户的收件箱以查看他们是否已经收到通知，但我认为如果他们在单击“接受”之前尚未实际收到电子邮件(服务器延迟？)，那么这不会很好地工作。

这是我的代码。任何想法将不胜感激。

public partial class ThisAddIn
{
    Outlook.Items _Appointments = null;
    Outlook.Folder _MyAppointmentsFolder = null;

    private void ThisAddIn_Startup(object sender, System.EventArgs e)
    {
        // Initialization.
        _MyAppointmentsFolder = (Outlook.Folder)this.Application.Session.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderCalendar);
        _Appointments = _MyAppointmentsFolder.Items;
        _Appointments.ItemAdd += new Outlook.ItemsEvents_ItemAddEventHandler(appointments_Add);
    }

    private void appointments_Add(object item)
    {
        // An appointment has been added. Read the title and send an email based on a condition.
        Outlook.AppointmentItem meetingItem = item as Outlook.AppointmentItem;
        if (meetingItem.Subject.Contains("Service Call"))
        {
            // Let's send ourselves an email.
            string emailTo = string.Format("{0}@concurrency.com", Environment.UserName);
            string subject = meetingItem.Subject;
            string body = meetingItem.Body;
            string startDate = meetingItem.Start.ToString();
            string endDate = meetingItem.End.ToString();

            SendEmailAlert(emailTo, subject, body, startDate, endDate);
        }

    }
    ....

Answer 1

如果您在发送电子邮件后将 meetingItem.GlobalAppointmentID 的值分配给类级别变量，并在发送前检查该值，这应该可以防止电子邮件发送两次。我对此方法进行了一些测试，似乎效果很好。这是我更新的代码:

...

string _PreviousMeetingId = string.Empty; // class-level variable

...

private void appointments_Add(object item)
    {
        // An appointment has been added. Read the title and send an email based on a condition.
        Outlook.AppointmentItem meetingItem = item as Outlook.AppointmentItem;
        if (meetingItem.Subject.Contains("Service Call") && _PreviousMeetingId != meetingItem.GlobalAppointmentID)
        {
            // Let's send ourselves an email.
            string emailTo = string.Format("{0}@concurrency.com", Environment.UserName);
            string subject = meetingItem.Subject;
            string body = meetingItem.Body;
            string startDate = meetingItem.Start.ToString();
            string endDate = meetingItem.End.ToString();

            SendEmailAlert(emailTo, subject, body, startDate, endDate);

            // Save the ID of the meeting so we can check it later (above).
            _PreviousMeetingId = meetingItem.GlobalAppointmentID;
        }

    }