While working on TDO-Forum, I had to generate a RSS feed for new “forum posts”, not just posts but posts and comments. So I was digging into the RSS feed code. And I discovered something kind of neat.

I knew you get an RSS feed for posts with a specific tag in Wordpress 2.3. I used it on the TDO Mini-Forms plugin as a news page. But did you know you can get an RSS feed for a search too? Neither the tag nor the search rss feed seem to be really support by template tags so you can’t really access them normally within a theme or from a Wordpress enabled webpage.

BTW If you have a site using FeedBurner to wrap RSS feeds and you are using FeedBurner FeedSmith plugin, then this won’t work. This plugin will wrap your posts RSS feed and ignore tag and search distinctions. I did a bit of hacking in th version of this plugin I use on this site to make this post work.

To get an RSS feed for posts with a specific tag, go to the tag archive and, if the site is using fancy permalinks, add “/feed/” to the end of the url. If it’s not using fancy permalinks, add “&feed=rss2″ instead. You can tell a site is not using fancy permalinks if the tag archive URL is like this: http://[site-url]/?tag=tag_slug (i.e. it contains a “?”).

For example: the URL for any posts tagged with Wordpress on this site is:

http://thedeadone.net/tag/wordpress/

The non-fancy-permalink version would be:

http://thedeadone.net/?tag=wordpress

Now to get an RSS feed for that tag you change the URL like this for fancy permalinks:

http://thedeadone.net/tag/wordpress/feed

Change the non-fancy permalink like this:

http://thedeadone.net/?tag=wordpress&feed=rss2

For search, it’s slightly simpler as there does not seem to be a fancy permalink for searches. So do a search for wordpress on my site (you can use the searchbox up there in the top). You’ll end up with a URL like this:

http://thedeadone.net/?s=wordpress

Now just add “&feed=rss2″ to the end and you get a feed for any posts on my blog that mention wordpress.

http://thedeadone.net/?s=wordpress&feed=rss2

This feed will pick up any post I happen to mention the word “Wordpress” in.

Quite neat isn’t it? Now if there was some proper template tags for these feeds I’m sure more themes would natively support them.

What’s the use of using a search rss feed over a tag rss feed? Well you want your blog posts the way you want to read them don’t you? For example, I do not always tag any post about TDOMF with TDOMF. I only tag thoses posts with TDOMF that are relevant to users of TDOMF. But you might want to know everything and anything about TDOMF, so you could use the search rss feed to keep up to date!

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.

Download Plugin Now from Wordpress.org!

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 “+”.

• Example not using fancy permalinks: “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.
• Example using fancy permalinks: “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).