RonR

restated (with slightly more detail) here: http://ronrothman.com/public/leftbraned/archives/2005/11/01/wordpress-fix-category-exclusions-in-next_post_linkprevious_post_link/

confirmed; it does not work (v1.5.2). in fact, it seems that the code isn’t even close to working correctly. to fix it, i’ve hacked up my installation as follows:

in file template-functions-links.php, at approximately line 221 (in function get_previous_post), you’ll see this:


$sql_exclude_cats = '';
if (!empty($excluded_categories)) {
$blah = explode('and', $excluded_categories);
foreach($blah as $category) {
$category = intval($category);
$sql_exclude_cats .= " AND post_category != $category";
}
}


i replaced that block with the following:

$sql_exclude_cats = '';
if (!empty($excluded_categories)) {
# ronr hack BEGIN
$query =
"SELECT post_id
FROM $wpdb->post2cat
WHERE category_id IN ("
. str_replace(',', ',', $excluded_categories)
. ')';
$excluded_post_rows = $wpdb->get_results($query);
if (count($excluded_post_rows) > 0) {
$sql_exclude_cats =
' AND ID NOT IN ('
. intval($excluded_post_rows[0]->post_id);
for ($i = 1; $i < (count($excluded_post_rows)); $i++) {
$sql_exclude_cats .= ',' . intval($excluded_post_rows[$i]->post_
id);
}
$sql_exclude_cats .= ')';
}
# ronr hack END
}


also did the same in get_next_post, a little farther down in the file.

my category excludes are just dandy now. i use them thus:


<?php next_post_link('%link
&raquo;', '%title', false, '15,16,17') ?>


note: my code does not do error checking, and it assumes that the parameters passed in are not screwy. <yada yada yada, other disclaimers omitted. constructive suggestions for improvements are always welcome, but please don’t bitch to me about my code; it’s provided as-is.>

presumably, this will be fixed properly in an upcoming release, so now that i’ve got it working (albeit jury-rigged), i’m not going to spend any more time on it. if it doesn’t get fixed in a future release, perhaps i’ll fold it into an asides plug-in.

anyway, good luck.

p.s., you can see the hack in action, here.

first of all: kudos, team! a great upgrade to a great product.

secondly, i’ve got a quick Q. i just did the 1.5 > 1.5.1 upgrade, and it went perfectly… almost.

the only thing which broke was my archives page, where this call started choking:

wp_list_cats(‘hide_empty=0&sort_column=name&optioncount=1&optiondates=1’);

the error message (which appeared several times–once for each category) was:

WordPress database error: [Unknown column 'cat_ID' in 'field list']
SELECT cat_ID, UNIX_TIMESTAMP( MAX(post_date) ) AS ts FROM wp_posts, wp_post2cat WHERE post_status = 'publish' AND post_id = ID GROUP BY category_id

i dug a little, and eventually changed “cat_ID” in the SELECT statement on wp-includes/template-functions-category.php line 293 to “category_id,” after which things began working as expected.

i’m not necessarily asking for help, since:

(a) it’s fixed (at least it seems to be),
(b) i’ve made some “customizations” (some might say “hacks”) to the WP files which very well could be related (though i don’t currently see how they could be), and
(c) i’m not a dumbass newbie who expects people to spend hours helping me, only to find that i didn’t follow directions (no offense to dumbass newbies–i was once one, too. 😀 )

i simply thought i’d throw this out there in case it helps anyone else, or on the off chance that it is in fact a WP bug. (if anyone wants more info, just ask. fwiw, my archive page is here.

thanks again to the dev team and the entire WP community for creating/supporting a kick-ass product.