Some fixes and extensions for WordPress tags such as a tag cloud using only tags found in a specific category and also tag and category intersection.
This plugin is simply intended as an example of how to implement tag and category intersections. However it has got a bit more feature-heavy recently. Please feel free to re-use the code in your plugin. This plugin is based on information found here.
Version 0.5 enables true 'or' tag intersection when using a category. It wasn't working prior to this (and no-one noticed). Thanks to Joel Giddey for spotting it.
WordPress 2.3 introduced native tagging support, which is rather nifty.
But did you know that you can display multiple tags in the one archive and even generate a feed for that?
http://your-blog-uri/?tag=tag1,tag2" this would get all the posts tagged with tag1 or tag2.
http://your-blog-uri/?tag=tag1+tag2" this would get all the posts tagged with tag1 and tag2
http://your-blog-uri/?tag=tag1,tag2&feed=rss" this would get you an RSS feed for all the posts tagged with tag1 or tag2
Neat huh? But did you notice that on the generated tag page you see only one tag listed in the header? This function fixes that and displays all tags used to generate that tag archive. It does this by silently modifying the
single_tag_title template tag. It'll even work on the RSS feed generated by that page!
What would be also be cool is to be able to intersect categories and tags so you could grab posts with tags from a specific category for example?
With this plugin you can. It's not perfect however. It only allows intersection between a single category and one or more tags. Technically WordPress should be able to support multiple categories and tags intersections but it didn't work for me in WordPress 2.3.x and 2.5.
So go to one of your category pages. If your using using fancy permalinks then at the end of the url add "
?tdo_tag=a_tag". If your not using permalinks then you can just use "
&tdo_tag=a_tag". You must use the tag slug, not the full tag name. You can use multiple tags as above using "," and "+".
http://your-blog-uri/?cat=35&tdo_tag=tag1,tag2" this would get all posts in category with id 35 and tagged with either tag1 or tag2.
http://your-blog-uri/category/mycategory/?tdo_tag=tag1+tag2" this would get all posts in the category "mycategory" and tagged with both tag1 and tag2.
This plugin uses this intersection code to automatically modify the built-in tag cloud template tag
wp_tag_cloud so that if it is used on a category archive, it shows only the tags within that category. You can then click on a tag in that tag cloud and it will get the posts for in that category that tagged with that tag. (You can disable this and just use the specific template as you need).