This is another way to apply tags to objects in your radiant site and retrieve objects by tag. If you're looking at this you will also want to look at the tags extension, which does a good job of tag-clouding and may be all you need, and at our library which uses this functionality to make an image gallery and document library and may be a useful starting point for other extensions.

This extension differs from tags in a few ways that matter to me but may not to you:

• We're not so focused on tag clouds - though you can still make them - but more on archival and linking functions.
• We replace the keywords mechanism on pages rather than adding another one.
• Anything can be tagged. By default we only do pages but other extensions can participate with a single line in a model class. See the taggable_events extension for a minimal example or just put is_taggable at the top of a model class and see what happens.
• We don't use has_many_polymorphs (it burns!)
• Or any of the tagging libraries: it only takes a few named_scopes
• it's multi-site compatible: if our fork is installed then you get site-scoped tags and taggings.

When you first install the extension you shouldn't see much difference: all we do out of the box is to take over (and make more prominent) the keywords field in the page-edit view.

I've just stripped out quite a lot of display clutter in order to focus on the basic tagging mechanism here. Retrieval and display is now handled by the library extension. The core radius tags remain here. Anything that used to refer to a tag page is probably now handled by the library page.

The underlying code is fairly well broken-in and has been in production for a couple of years, but I've rearranged it quite drastically and the interface is all new. There are tests now: not detailed but with reasonable coverage. Silly mistakes are getting less likely.

Not too bad, I think. Most of the heavy retrieval functions have been squashed down into single queries. Each of these:

Tag.most_popular(50)
Tag.coincident_with(tag1, tag2, tag3)
Page.tagged_with(tag1, tag2, tag3)
Page.related_pages 								# equivalent to Page.tagged_with(self.attached_tags) - [self]

is handled in a single pass.

The exception is the r:tag_cloud tag: there we have to gather a list of descendant pages first. It's done in a fairly frugal way (by generation rather than individual) but still likely to involve several preparatory queries as well as the cloud computation.

This extension creates several radius tags. There are two kinds:

are used in the usual to display the properties and associations of a given tag (which can be supplied to a library as a query parameter or just specified in the radius tag)

<r:tag:title />
<r:tag:description />
<r:tag:pages:each>...</r:tag:pages:each>

currently only available in a tag cloud (or a top_tags list):

<r:tag:use_count />

These display the tag-associations of a given page.

<r:if_tags>...</r:if_tags>
<r:unless_tags>...</r:unless_tags>
<r:tags:each>...</r:tags:each>
<r:related_pages:each>...</r:related_pages:each>
<r:tag_cloud [url=""] />

The library extension adds a lot more ways to retrieve lists of tags and tagged objects, and to work with assets in the same way as we do here with pages.

The calculation of prominence here applies a logarithmic curve to create a more even distribution of weight. It's continuous rather than banded, and sets the font size and opacity for each tag in a style attribute.

Add tags to your pages by putting a comma-separated list in the 'keywords' box. That's about to get more helpful.

Put this in your layout:

<r:if_tags>
  <h3>See also</h3>
  <ul>
    <r:related_pages.each>
      <li><r:link /></li>
    <r:related_pages.each>
  </ul>
</r:if_tags>

Include the sample tagcloud.css in your styles and put this somewhere in the page or layout:

<r:tag_cloud />

Seek venture capital immediately.

• auto-completer to improve tagging consistency.

• Radiant 0.8.1
• will_paginate gem

This is no longer compatible with 0.7 because we're doing a lot of :having in the scopes and you need rails 2.3 for that.

As usual:

git clone git://github.com/spanner/radiant-taggable-extension.git vendor/extensions/taggable
rake radiant:extensions:taggable:migrate
rake radiant:extensions:taggable:update

The update task will bring over a couple of CSS files for styling tags but you'll want to improve those.

Very likely. Github issues, please, or for little things an email or github message is fine.

• William Ross, for spanner. will at spanner.org
• Copyright 2009 spanner ltd
• released under the same terms as Rails and/or Radiant