MT Extensions: Avoiding Duplicate Comments 3.01

Hacks : Avoiding Duplicate Comments 3.01 Apr 09 2003 | # | C:20

April 09, 2003 - updated October 06, 2004

When a visitor submits a comment, sometimes it takes a while for the comment page to refresh to reflect that their comment was successfully added. During this time, the user may click the “Post” button again (and again…) which causes their comment to be submitted multiple times.

This hack modifies MovableType to simply ignore the same comment being entered multiple times for an entry. Two comments are considered the same if the comment text and the name, email address and url of the comment auther are exactly the same.

Note for users of Jay Allen’s MT-Blacklist: Instead of modifying Comments.pm, you should modify extlib/jayallen/MTBlPost.pm (in older versions of MT-Blacklist modify extlib/jayallen/Blacklist.pm).

lib/MT/App/Comments.pm Modification

Go to your MovableType installation directory, and open the file Comments.pm in the lib/MT/App subdirectory. Find the line that says:

    $comment->save;

and insert the following code before it:

    ## BEGIN HACK Avoid Duplicate Comments
    ## http://www.nonplus.net/software/mt/AvoidingDuplicateComments.htm
    if(my @existing_comments = MT::Comment->load({
                  blog_id => $comment->blog_id,
                  entry_id => $comment->entry_id})) {

      foreach my $c (@existing_comments) {
          next unless (($c->author||'') eq ($comment->author||'')
                  && ($c->email||'') eq ($comment->email||'')
                  && ($c->text||'') eq ($comment->text||''));

          my $link_url;
          if (!$q->param('static')) {
              my $url = $app->base . $app->uri;
              $url .= '?entry_id=' . $q->param('entry_id');
              $link_url = $url;
          } else {
              my $static = $q->param('static');
              if ($static == 1) {
                  $link_url = $entry->permalink;
              } else {
                  $link_url = $static . '#' . $c->id;
              }
          }
          return $app->redirect($link_url);
      }
    }
    ## END HACK Avoid Duplicate Comments

In MovableType 2.51 and 2.63, this modification is on lines 99 and 106, respectively.

Version History

3.01 October 14 2003
Describe integration with Jay Allen’s MT-Blacklist.
3.0 May 1 2003
Changed hack to work for all MT backends, including DB_File.
2.0 April 9 2003
In addition to comment text, also compare author name, email and URL.
1.0 April 9 2003
Initial hack, only compared comment text.

Comments

Cool! Can we do this for trackbacks?
Posted by: Michael on April 9, 2003 10:52 AM
For some odd reason, it won’t work with my comments :-( I’m getting repeats. But I’ll try again! Thanks.
Posted by: Beatriz on April 10, 2003 09:22 PM
Oy, if you’re using Berkeley DB for your blog, then I’m afraid this hack won’t work.

One could write a hack that would work with DB_File, but I’m not going to bother - it wouldn’t be as efficient and, really, this is another good reason to switch over to MySQL :-)
Posted by: Stepan on April 11, 2003 06:00 PM
Thank you!!
Posted by: Maggie on April 12, 2003 06:40 PM
Suweet! Thanks! This is one of the few hacks I’ve ever seen enough need for to be worth porting the code at upgrade time.
Posted by: *** Dave on April 25, 2003 09:13 PM
this thing doesn’t working for me and I am using mysql
Posted by: iced glare on May 1, 2003 03:22 PM
this hack seems to prevent links from breaking into a new window from the pop-up comments.

if you check out this link, i am using javascript to allow embedded web links to pop-up in a new window. using this hack seems to nulify the javacode (the links stay within the pop-up window). any suggestions?
Posted by: pat on May 3, 2003 06:44 AM
sorry, the link got stripped. it is here:

http://www.movabletype.org/support/index.php?act=ST&f=10&t=3136&hl=&s=5ca2c6ddd5dc8c28b32705d751ef0606
Posted by: pat on May 3, 2003 06:45 AM
Hi Step :) Just wanted to thank you for making it possible for DB users to implement the hack; I tried it and it worked. I’m now under SQL and will install it again.
Posted by: Beatriz on May 15, 2003 05:30 PM
Hey I decided to try this out again because I keet getting repeat comments and after reading carefully this time I realized that I had changed the wrong comments.pm..I didn’t go to lib/MT/App/comments.pm the first time I went to lib/MT/comments.pm..that’s probably why it didn’t work.
I am so glad that you had emailed me back that time to see what the problem was because I couldn’t remember the URL and then I remembered the reply email :-)
Posted by: iced glare on May 18, 2003 02:07 AM
What a minute besides changing the comments.pm ..is there a plugin that need to be installed in mysql???
Posted by: iced glare on May 18, 2003 02:11 AM
No additional plugin needs to be installed. You only need to modify the lib/MT/App/Commens.pm file as described in the hack.

Make sure you put that hack code before the $cooment>>save; line, otherwise it won’t work!
Posted by: stepan on May 18, 2003 08:41 AM
Rather than resorting to a bunch of hacking around, you might prefer just adding in a simple message like:

alert(‘Thanks for the message. Please be patient while it is being processed. This may take a few extra moments…’);

Seems more straight-forward to me, but who am I to say this?
Posted by: Kiffin on December 13, 2003 02:33 PM
By all means, there are other alternatives to this hack. For example disabling the Post button once it has been clicked works well and would be less intrusive than a popup message.

Of course, you then have to modify all templates that have a comment form and script based methods won’t work at all in browsers that don’t support Javascript or have it disabled.
Posted by: stepan on December 13, 2003 04:00 PM
Thanks!
Posted by: melissa on December 22, 2003 07:39 PM
I’m having problems setting this up with Jay Allen’s MT-Blacklist 1.65, I can’t seem to find $comment->save; as instructed above
Posted by: Sian on January 3, 2004 12:42 PM
Sian, as per http://www.jayallen.org/projects/mt-blacklist/latest/#partial_incompatibilities, you need to make the change in MTBlPost.pm around line 110.

—Kynn
Posted by: Kynn Bartlett on January 10, 2004 03:55 AM
I’m using this with Jay Allen’s MT-Blacklist and I have noticed an added benefit.

If someone now hits the post button multiple times, it seems to greatly speed up the posting proccess.

Thanks!!!!!!!
Posted by: David on March 26, 2004 10:35 AM
Thanks a lot!
Posted by: Mania on August 19, 2004 04:35 PM
An error occurred:

syntax error at extlib/jayallen/MTBlPost.pm line 150, near “>”
syntax error at extlib/jayallen/MTBlPost.pm line 151, near “; $comment”
syntax error at extlib/jayallen/MTBlPost.pm line 152, near “})”
Compilation failed in require at plugins/Blacklist.pl line 114.

Using MT 2.63 and MT-blacklist 1.64

BTW I got 2 times $comment->save; in extlib/jayallen/MTBlPost.pm

Posted by: Erik van Roekel on August 27, 2004 06:36 AM