From e7bf3ba38ee156afb2ede0ac95da17e78c89f629 Mon Sep 17 00:00:00 2001
From: Alex Reisner <alex@alexreisner.com>
Date: Thu, 24 Mar 2011 20:29:54 -0400
Subject: [PATCH] Add approximate distance/bearing calculations.
Just for interface consistency across database types. NOT for accuracy!
---
lib/geocoder/orms/active_record.rb | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/lib/geocoder/orms/active_record.rb b/lib/geocoder/orms/active_record.rb
index 5123618f..ea20205c 100644
--- a/lib/geocoder/orms/active_record.rb
+++ b/lib/geocoder/orms/active_record.rb
@@ -135,9 +135,29 @@ module Geocoder::Orm
# rather than a circle, so results are very approximate (will include
# objects outside the given radius).
#
+ # Distance and bearing calculations are *extremely inaccurate*. They
+ # only exist for interface consistency--not intended for production!
+ #
def approx_near_scope_options(latitude, longitude, radius, options)
+ lat_attr = geocoder_options[:latitude]
+ lon_attr = geocoder_options[:longitude]
+ options[:bearing] = :linear unless options.include?(:bearing)
+ if options[:bearing]
+ bearing = "CASE " +
+ "WHEN (#{lat_attr} >= #{latitude} AND #{lon_attr} >= #{longitude}) THEN 45.0 " +
+ "WHEN (#{lat_attr} < #{latitude} AND #{lon_attr} >= #{longitude}) THEN 135.0 " +
+ "WHEN (#{lat_attr} < #{latitude} AND #{lon_attr} < #{longitude}) THEN 225.0 " +
+ "WHEN (#{lat_attr} >= #{latitude} AND #{lon_attr} < #{longitude}) THEN 315.0 " +
+ "END"
+ else
+ bearing = false
+ end
+ distance = "(69 * ABS(#{lat_attr} - #{latitude}) / 2) + " +
+ "(60 * ABS(#{lon_attr} - #{longitude}) / 2)"
default_near_scope_options(latitude, longitude, radius, options).merge(
- :select => options[:select] || nil
+ :select => "#{options[:select] || '*'}, " +
+ "#{distance} AS distance" +
+ (bearing ? ", #{bearing} AS bearing" : ""),
)
end
--
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