Question

    List<Comment> StreamItemComments = objStreamItem.GetComments();

…

    foreach (Comment Item in StreamItemComments)
        {
            if (ClientUser.UserName != Item.Sender)
            {
                Notification notificationObj = new Notification
                {
                    Sender = ClientUser.UserName,
                    Recipient = Item.Sender,
                    Value = "whatever value here",
                    TrackBack = "",
                    IsRead = false
                };
                notificationObj.Add();
            }
        }

What if there are two ‘username’ in List in Item.Sender. I’d like to send a notification once to the user. Here if there are duplicate usernames it will send two notifications because i am not filtering out duplicate Item.Senders from the list in StreamItemComments.

Answer 1

Consider writing a query to state your intentions. You want the distinct senders of the item comments, but only where the sender is not the client user. Sounds like a query, does it not?

var recipients = StreamItemComments
                    .Where(item => item.Sender != ClientUser.UserName)
                    .Select(item => item.Sender)
                    .Distinct();

You can then use this query to build your notifications

foreach (var item in recipients)
{
    var notificationObj = new Notification
    {
         Sender = ClientUser.UserName,
         Recipient = item,
         ...
    }

    notificationObj.Add();
}

You could also fit this object construction into the query, as well, but with your .Add() invocation on each object, I left it out of the query. It wouldn’t be difficult to incorporate, although you’d still need to loop over the output and invoke .Add() for each result.