From 315120ffc18b0448fbcccc2bd27fb05b6d569018 Mon Sep 17 00:00:00 2001
From: Alex Reisner <alex@alexreisner.com>
Date: Sat, 23 May 2009 09:48:56 -0400
Subject: [PATCH] Add order, limit, and offset options to nearby_mysql_query
method.
---
lib/geocoder.rb | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/lib/geocoder.rb b/lib/geocoder.rb
index 4b795828..7cabb49d 100644
--- a/lib/geocoder.rb
+++ b/lib/geocoder.rb
@@ -102,12 +102,21 @@ module Geocoder
# Find all records within a radius (in miles) of the given point.
# Taken from excellent tutorial at:
# http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL
+ #
+ # Options hash may include:
+ #
+ # +latitude+ :: name of column storing latitude data
+ # +longitude+ :: name of column storing longitude data
+ # +order+ :: column(s) for ORDER BY SQL clause
+ # +limit+ :: number of records to return (for LIMIT SQL clause)
+ # +offset+ :: number of records to skip (for LIMIT SQL clause)
#
def self.nearby_mysql_query(table, latitude, longitude, radius = 20, options = {})
# Alternate column names.
options[:latitude] ||= 'latitude'
options[:longitude] ||= 'longitude'
+ options[:order] ||= 'distance ASC'
# Constrain search to a (radius x radius) square.
factor = (Math::cos(latitude * Math::PI / 180.0) * 69.0).abs
@@ -117,6 +126,13 @@ module Geocoder
lat_hi = latitude + (radius / 69.0);
where = "#{options[:latitude]} BETWEEN #{lat_lo} AND #{lat_hi} AND " +
"#{options[:longitude]} BETWEEN #{lon_lo} AND #{lon_hi}"
+
+ # Build limit clause.
+ limit = ""
+ if options[:limit] or options[:offset]
+ options[:offset] ||= 0
+ limit = "LIMIT #{options[:offset]},#{options[:limit]}"
+ end
# Generate query.
"SELECT *, 3956 * 2 * ASIN(SQRT(" +
@@ -125,7 +141,8 @@ module Geocoder
"COS(#{options[:latitude]} * PI() / 180) * " +
"POWER(SIN((#{longitude} - #{options[:longitude]}) * " +
"PI() / 180 / 2), 2) )) as distance " +
- "FROM #{table} WHERE #{where} HAVING distance <= #{radius}"
+ "FROM #{table} WHERE #{where} HAVING distance <= #{radius} " +
+ "ORDER BY #{options[:order]} #{limit}"
end
##
--
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