Recently at Helpful Technology I was working on the new Foreign Office Blogs website – collapsing their massive WordPress multisite instance down into a standard single site install. When I say massive… it was 161 sites with 448 users spread across ~4500(!) database tables and nearly 5GB of files. Oh, and it’s multilingual too.

One of the big, and somewhat unexpected, challenges to workflow once it was merged was comments. As WordPress presents the number of comments in the admin bar as well as the admin menu, authors were getting confused about whether they had any comments to respond to / manage, or if they were for other authors. While on the Posts screen you do at least get a Mine filter so that you can view just your own posts (along with the standard All, Published, Draft and Bin/Trash), there is nothing similar for Comments.
Also, WordPress helpfully puts a big notification bubble next to Comments in the menu as well as in the admin bar that shows the total number of Pending comments – again, not Author specific.

Part 1 – the list of comments

This first issue is actually the easiest to deal with – there is a helpful hook pre_get_comments that allows you to modify the wp_query arguments used to generate the Comments list.
All that’s needed is a simple finction that does a couple of sanity checks to make sure you are on edit-comments.php and the user is an Author (Editors and above have the rights to view and manage others posts so affecting them doesn’t really make sense^*) and then $query->query_vars['post_author'] = $user_ID; does the magic.

Part 2 – comment counts

Changing the comment counts is actually a lot harder as there is no hook you can use to manipulate it as simply. Internally WordPress uses wp_count_comments which takes a single (optional) argument, a Post ID. It’s all or nothing, so to speak – it either returns the comment counts for the whole blog, or for a single blog post. There is a filter which lets you inject replacement values into the function however, so we have a way in. We can create a duplicate of this function, and then use the duplicate as a filter for the core function to inject the comment counts for just the logged in user.
But how do you get the count for a single user? Comments are associated with posts not users… Here caching is going to be your friend. We first have to do a standard query for all posts by the user WP_Query( array('author' => $user_ID,'posts_per_page' => -1) );, and then loop over each post, get the comments, and add up the number. This is comparably intensive so we can store the results in a transient for a length of time that makes sense for your blog. One thing to watch out for is that wp_count_comments expects a stdClass Object so remember to cast the array just before returning it.

^*You could take this further and read some custom meta from the current user that specifies which other users they manage to determine which to show, but that’s for another day…

Putting it all together

Either build this into a simple plugin or put it into your theme’s functions.php depending on your needs: