目前我的代码，还不算太花哨。
每行都必须有会议ID值。如果会议对象中没有会议ID，则返回错误并停止所有进程（列表中每行的会议ID都相同）。
议程项目是必要的，而且不能是重复的值。如果遗漏或重复，则会传回错误。
如果缺少Legistar ID，则议程项目的值将分配给缺少的Legistar ID。
议程项目和/或Legistar ID都不能包含重复值这些属性每个值都必须唯一否则，将停止，并返回错误
我尝试传递并验证的列表如下所示：

AgendaItem  LegistarID  Title
1   74490   Public Comment. (October 31 2022)
2   74491   Welcome Affirmative Action Commission Appointment. <-- Agenda Item 2
2   73403   Nomination Open Update.                            <-- Agenda Item 2
4   74490   Communication Strategy Update.                     <-- Legistar Id same as row 1

如何传递指定此类特定情况的消息，以便客户端应用程序接收并提醒用户？
这是我的ImportData例程的当前版本，这里没有任何内容

public ActionResult ImportData(List<MeetingAgendaXref_WIP> meeting) // see comment above procedure name
{

    bool status = false;
    string message = "";

    try
    {
        if (ModelState.IsValid)
        {
            var errors = new List<string>();
            var rowCounter = 1;

            using (ClerkEntities db = new ClerkEntities())
            {
                foreach (var i in meeting)
                {

                    if (i.MeetingID == 0)
                    {

                        message = string.Format("No Meeting ID. Please make sure that the Cross Reference meets the required criteria for each row before clicking the ""Upload"" button.");
                        // log error to list
                        errors.Add($"Row {rowCounter}: No Meeting ID. Please make sure that the Cross Reference meets the required criteria for each row before clicking the ""Upload"" button.");
                        return new JsonResult { Data = new { status = status, message = message } };

                    }

                    if (i.AgendaItem == 0)
                    {
                        message = string.Format("No Agenda Item. Please make sure that the Cross Reference file meets the required criteria for each row before clicking the ""Upload"" button.");
                        // log error to list
                        errors.Add($"{rowCounter}:No Agenda Item. Please make sure that the Cross Reference file meets the required criteria for each row before clicking the ""Upload"" button.");
                        return new JsonResult { Data = new { status = status, message = message } };
                    }

                    // if Legistar ID, 
                    if (i.LegistarID == 0)
                    {
                        // and Agenda Item are not present, return error message, log error message
                        if (i.AgendaItem == 0)
                        {
                            message = string.Format("Agenda Item, and Legistar Id are missing. Please make sure that the Cross Reference file meets the required criteria for each row before clicking the ""Upload"" button.");
                            // log error to list
                            errors.Add("Agenda Item, and Legistar Id are missing. Please make sure that the Cross Reference file meets the required criteria for each row before clicking the ""Upload"" button.");
                            return new JsonResult { Data = new { status = status, message = message } };
                        }
                        // otherwise, if legistar id, is empty, but agenda item is not, then assign Agenda Item to Legistar Id.
                        else
                        {
                            i.LegistarID = i.AgendaItem;
                        }
                    }

                    var compositeKey = db.MeetingAgendaXref_WIP.Find(i.MeetingID, i.AgendaItem);

                    if (compositeKey == null)
                    {
                        // Add new
                        db.MeetingAgendaXref_WIP.Add(i);

                    }
                    else
                    {
                        // Update previously saved values (same or new)
                        db.Entry(compositeKey).CurrentValues.SetValues(i);
                        db.Entry(compositeKey).State = EntityState.Modified;
                    }
                    rowCounter++;
                }
                
                // If there are errors do not save and return error message
                if (errors.Count > 0)
                {
                    return new JsonResult { Data = new { status = status, message = string.Join("\n", errors) } };
                }
                else
                {
                    db.SaveChanges();
                    message = string.Format(@"Your Cross Reference file has been uploaded successfuly!");
                    status = true;
                    return new JsonResult { Data = new { status = status, message = message } };
                }
            }
        }
        else
        {
            message = string.Format(@"Please make sure that the Cross Reference file meets the required criteria for each row before clicking the ""Upload"" button.");
            return new JsonResult {Data = new {status = status, message = message}};
        }
    }
    catch (System.ArgumentException ex)
    {
        status = false;
        ExceptionLogging.WriteLogError(ex.ToString());
    }
    return new JsonResult {Data = new {status = status, message = message}};
}