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copied!<p>Here's a quick way to do this. These will simply return arrays of ActiveRecord objects.</p> <pre><code>class Area def events Event.joins("INNER JOIN areas ON areas.id=#{id} AND st_contains(areas.geometry, events.geometry)").all end end class Event def areas Area.joins("INNER JOIN events ON events.id=#{id} AND st_contains(areas.geometry, events.geometry)").all end end </code></pre> <p>You probably should memoize (cache the result) so that you don't query the database every time you call the method. That should be straightforward; I leave it as an exercise for the reader.</p> <p>It <em>may</em> be possible to get sophisticated and wrap this up in a true Rails association proxy (so you can get all the Rails association goodies). I haven't looked into this though. It wouldn't be a standard Rails association in any case, because you're not storing IDs.</p> <p>Twelfth is right: you should create spatial indexes for both tables. Activerecord-postgis-adapter should make those easy to do in your migration.</p> <pre><code>change_table :events do |t| t.index :geometry, :spatial => true end change_table :areas do |t| t.index :geometry, :spatial => true end </code></pre> <p>If you're having trouble with installing postgis, I recently wrote up a bunch of blog entries on this stuff. Check out <a href="http://www.daniel-azuma.com/blog/archives/category/tech/georails" rel="noreferrer">http://www.daniel-azuma.com/blog/archives/category/tech/georails</a>. I'm also the author of rgeo and activerecord-postgis-adapter themselves, so I'm happy to help if you're stuck on stuff.</p>

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