From 72041be4221e43eda54795f6956653622bb74988 Mon Sep 17 00:00:00 2001
From: Adrian Short <adrian.short@gmail.com>
Date: Tue, 26 Jun 2012 12:36:11 +0100
Subject: [PATCH] Added geospatial index and search

---
 app/models/post.rb | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/app/models/post.rb b/app/models/post.rb
index 50cf3db..59d1055 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -10,5 +10,17 @@ class Post
   key :loc,         Hash # { lng, lat }
   timestamps!
 
+  ensure_index [[:loc, '2d']]
+
   belongs_to :feed
+  
+  EARTH_RADIUS_KM = 6378.0
+  
+  def self.near(lat, lng, radius_km)
+    all(
+      :loc => {
+        '$nearSphere' => [ lng, lat ],
+        '$maxDistance' => radius_km / EARTH_RADIUS_KM
+    })
+  end
 end