Module: Geocoder::ClassMethods

Defined in:
lib/geocoder.rb

Overview

Methods which will be class methods of the including class.

Instance Method Summary collapse

Instance Method Details

#_get_coordinates(object) ⇒ Object

Get the coordinates [lat,lon] of an object. This is not great but it seems cleaner than polluting the object method namespace.



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# File 'lib/geocoder.rb', line 110

def _get_coordinates(object)
  [object.send(geocoder_options[:latitude]),
  object.send(geocoder_options[:longitude])]
end

#find_near(location, radius = 20, options = {}) ⇒ Object

DEPRECATED: Please use the near method/named scope instead.



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# File 'lib/geocoder.rb', line 48

def find_near(location, radius = 20, options = {})
  warn "Geocoder deprecation warning: the 'find_near' class method is " +
    "deprecated, please use the 'near' method, which is a named scope."
  near(location, radius, options)
end

#near_scope_options(latitude, longitude, radius = 20, options = {}) ⇒ Object

Get options hash suitable for passing to ActiveRecord.find to get records within a radius (in miles) of the given point. Taken from excellent tutorial at: www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL

Options hash may include:

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)



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# File 'lib/geocoder.rb', line 66

def near_scope_options(latitude, longitude, radius = 20, options = {})

  # set defaults/clean up arguments
  options[:order] ||= 'distance ASC'
  radius            = radius.to_i

  # constrain search to a (radius x radius) square
  factor = (Math::cos(latitude * Math::PI / 180.0) * 69.0).abs
  lon_lo = longitude - (radius / factor);
  lon_hi = longitude + (radius / factor);
  lat_lo = latitude  - (radius / 69.0);
  lat_hi = latitude  + (radius / 69.0);

  # build limit clause
  limit = nil
  if options[:limit] or options[:offset]
    options[:offset] ||= 0
    limit = "#{options[:offset]},#{options[:limit]}"
  end
  
  # generate hash
  lat_attr = geocoder_options[:latitude]
  lon_attr = geocoder_options[:longitude]
  {
    :select => "*, 3956 * 2 * ASIN(SQRT(" +
      "POWER(SIN((#{latitude} - #{lat_attr}) * " +
      "PI() / 180 / 2), 2) + COS(#{latitude} * PI()/180) * " +
      "COS(#{lat_attr} * PI() / 180) * " +
      "POWER(SIN((#{longitude} - #{lon_attr}) * " +
      "PI() / 180 / 2), 2) )) as distance",
    :conditions => [
      "#{lat_attr} BETWEEN ? AND ? AND " +
      "#{lon_attr} BETWEEN ? AND ?",
      lat_lo, lat_hi, lon_lo, lon_hi],
    :having => "distance <= #{radius}",
    :order  => options[:order],
    :limit  => limit
  }
end