Craig Ambrose

PluginInstances - a Different Way to Use Rails Plugins

I’ve just released the PluginInstances pluging at: http://github.com/craigambrose/plugin_instances/

This plugin allows you to have individual route sets for other plugins, including a unique instance id.

Without using this plugin you can specify a routes.rb in your plugins (as of rails 2.3), and these routes are merged into the global route set used when determining how to process the current request. This is great for allowing a plugin to introduce a set of functionality which exists only once on the site (like a login system).

The PluginInstances plugin is designed to enable individual instances of plugins to be placed in different places on the site. For example, lets say that your site is content managed, and has tabs across the top which link to various types of functionality:

In your application’s routes.rb file:

1
  map.plugin_instances "/tabs/:id"

When a request is detected with a path like “/tabs/23/admin”, it realises that this matches the plugin_instances route, finds the relevant instance (eg: PluginInstance.find(23)), asks that instance what plugin it represents (eg: a forum, user profile, etc), and then passes the route “/admin” to the route set for that plugin, along with the plugin instance object. Thus, a forum plugin could be written which can be instantiated at different places in the site, and just has to scope itself using the plugin instance id.

For detailed usage instructions, see the README file displayed at the github project page.

I’m using this plugin at present to build a pluggable wiki, where each new page that you create could be just a simple page of versioned text (like a regular wiki), or it could be a calendar, a forum, etc. People using drupal will also find this sort of routing system familiar, so I’m sure there are plenty of other useful applications for it.