get distinct list of child nodes based on properties

Nigel Wilson 945 posts 2077 karma points

Mar 02, 2013 @ 02:38

Hey there

I have written some code which is almost working how I want it to, but am somewhat stumped onone smallpart.

I have a page on my site with the ability to add a comment. I want to include a checkbox so that commentors can subscribe to receive an email notification when a new comment is posted.

So I am trying to write some code to loop through all comments under the page and build a list of email addresses to send to.

The comment node has the following properties - name (textbox), email (textbox), notify (true/false) and comment (textbox multiple).

My code so far is as follows (triggered via the publish event on the comment document type)

public class emailRecipient
    {
        public string name { get; set; }
        public int id { get; set; }
        public string email { get; set; }
    }

public static void sendEmailsToCommentors(Document comment)
        {
            Node parent = new Node(comment.Parent.Id);
            List _commentNodes = parent.AllDescendants().Where(n => n.GetPropertyAsString("receiveNotifications") == "1").ToList();
            
            var distinctEmailNodes = (from loc in _commentNodes
                                  select new emailRecipient
                                  {
                                      email = loc.GetPropertyAsString("email"), 
                                      id = loc.Id, 
                                      name = loc.GetPropertyAsString("name")
                                  }
                                  ).Distinct();
  foreach (var n in distinctEmailNodes)
        { 
     //Send email code goes here
    }

The above is working and sending emails, however it is not creating a distinct list, rather sending to all nodes where the "notify" property is set to true. Therefore if someone has commented more than once they will get multiple emails.

Whislt I can appreciate why the Distinct() isn't working, I haven't been able to figure out a solution.

Can anyone provide any suggestions? Also feel free to comment on if there is a better alternative way.

I do appreciate there are packages for commenting, however wanted to have a play myself in order to provide a bit of personal development.

Cheers, Nigel

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Nigel Wilson 945 posts 2077 karma points

Mar 02, 2013 @ 03:19

Ahh wouldn't ya know it - Google is my friend and i have created a solution immediately after posting my original question...

So I still have the following class

public class emailRecipient
    {
        public string name { get; set; }
        public int id { get; set; }
        public string email { get; set; }
    }

But the logic has changed as follows:

public static void sendCommentorNotifications(Document comment)
        {
            Node parent = new Node(comment.Parent.Id);
            var emailNodes = (from loc in parent.AllDescendants() 
                              select new emailRecipient
                              {
                                  email = loc.GetPropertyAsString("email"),
                                  id = loc.Id,
                                  name = loc.GetPropertyAsString("name")
                              }
                                  );

            var distinctItems = emailNodes.Distinct(new DistinctItemComparer());

            foreach (var n in distinctItems)
            {
                //Send email logic
            }
        }

And then as a separate class I have an equality comparer (this bit was the missing piece of the puzzle)

class DistinctItemComparer : IEqualityComparer
    {
        public bool Equals(emailRecipient x, emailRecipient y)
        {
            return x.email == y.email;
        }
        public int GetHashCode(emailRecipient obj)
        {
            return obj.email.GetHashCode();
        }
    }

Upward and onward

Nigel

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Hendy Racher 863 posts 3849 karma points MVP 2x admin c-trib

Mar 02, 2013 @ 10:54

Hi Nigel,

Just tried the following (in a razor script) in v6, and this seems to work too:

foreach(Node comment in uQuery.GetNodesByType("Comment")
                              .Where(node => node.GetProperty<bool>("recieveNotificiations"))
                              .DistinctBy(node => node.GetProperty<string>("email")))
{
    @(comment.GetProperty<string>("email"))
}

The .DistictBy() method is in the Umbraco.Core.EnumerableExtensions (but not sure in which version of Umbraco this was added).

Hendy

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Get Distinct List of Child Nodes Based on Properties