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- class Post < ActiveRecord::Base
- belongs_to :feed
-
- EARTH_RADIUS_METRES = 6378000
-
- def self.near(lat, lon, radius_metres)
- # Santize inputs. Is this necessary?
- lat = lat.to_f
- lon = lon.to_f
- radius_metres = radius_metres.to_i
-
- # Calculate distance using the Haversine formula
- self.find_by_sql(<<-ENDQUERY
- SELECT
- p.id,
- p.title,
- p.summary,
- p.url,
- p.lat,
- p.lon,
- p.published,
- f.title as feed_title,
- ( #{EARTH_RADIUS_METRES}
- * acos( cos( radians('#{lat}') )
- * cos( radians( p.lat ) )
- * cos( radians( p.lon )
- - radians('#{lon}') )
- + sin( radians('#{lat}') )
- * sin( radians( p.lat ) ) ) )
- As distance
-
- FROM posts p
- INNER JOIN feeds f
- ON p.feed_id = f.id
-
- WHERE
- ( #{EARTH_RADIUS_METRES}
- * acos( cos( radians('#{lat}') )
- * cos( radians( p.lat ) )
- * cos( radians( p.lon )
- - radians('#{lon}') )
- + sin( radians('#{lat}') )
- * sin( radians( p.lat ) ) ) )
- <= #{radius_metres}
-
- ORDER BY distance
-
- ENDQUERY
- )
- end
- end
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