module GeoKit
# Contains the class method acts_as_mappable targeted to be mixed into ActiveRecord.
# When mixed in, augments find services such that they provide distance calculation
# query services. The find method accepts additional options:
#
# * :origin - can be
# 1. a two-element array of latititude/longitude -- :origin=>[37.792,-122.393]
# 2. a geocodeable string -- :origin=>'100 Spear st, San Francisco, CA'
# 3. an object which responds to lat and lng methods, or latitude and longitude methods,
# or whatever methods you have specified for lng_column_name and lat_column_name
#
# Other finder methods are provided for specific queries. These are:
#
# * find_within (alias: find_inside)
# * find_beyond (alias: find_outside)
# * find_closest (alias: find_nearest)
# * find_farthest
#
# Counter methods are available and work similarly to finders.
#
# If raw SQL is desired, the distance_sql method can be used to obtain SQL appropriate
# to use in a find_by_sql call.
module ActsAsMappable
# Mix below class methods into ActiveRecord.
def self.included(base) # :nodoc:
base.extend ClassMethods
end
# Class method to mix into active record.
module ClassMethods # :nodoc:
# Class method to bring distance query support into ActiveRecord models. By default
# uses :miles for distance units and performs calculations based upon the Haversine
# (sphere) formula. These can be changed by setting GeoKit::default_units and
# GeoKit::default_formula. Also, by default, uses lat, lng, and distance for respective
# column names. All of these can be overridden using the :default_units, :default_formula,
# :lat_column_name, :lng_column_name, and :distance_column_name hash keys.
#
# Can also use to auto-geocode a specific column on create. Syntax;
#
# acts_as_mappable :auto_geocode=>true
#
# By default, it tries to geocode the "address" field. Or, for more customized behavior:
#
# acts_as_mappable :auto_geocode=>{:field=>:address,:error_message=>'bad address'}
#
# In both cases, it creates a before_validation_on_create callback to geocode the given column.
# For anything more customized, we recommend you forgo the auto_geocode option
# and create your own AR callback to handle geocoding.
def acts_as_mappable(options = {})
# Mix in the module, but ensure to do so just once.
return if self.included_modules.include?(GeoKit::ActsAsMappable::InstanceMethods)
send :include, GeoKit::ActsAsMappable::InstanceMethods
# include the Mappable module.
send :include, Mappable
# Handle class variables.
cattr_accessor :distance_column_name, :default_units, :default_formula, :lat_column_name, :lng_column_name, :qualified_lat_column_name, :qualified_lng_column_name
self.distance_column_name = options[:distance_column_name] || 'distance'
self.default_units = options[:default_units] || GeoKit::default_units
self.default_formula = options[:default_formula] || GeoKit::default_formula
self.lat_column_name = options[:lat_column_name] || 'lat'
self.lng_column_name = options[:lng_column_name] || 'lng'
self.qualified_lat_column_name = "#{table_name}.#{lat_column_name}"
self.qualified_lng_column_name = "#{table_name}.#{lng_column_name}"
if options.include?(:auto_geocode) && options[:auto_geocode]
# if the form auto_geocode=>true is used, let the defaults take over by suppling an empty hash
options[:auto_geocode] = {} if options[:auto_geocode] == true
cattr_accessor :auto_geocode_field, :auto_geocode_error_message
self.auto_geocode_field = options[:auto_geocode][:field] || 'address'
self.auto_geocode_error_message = options[:auto_geocode][:error_message] || 'could not locate address'
# set the actual callback here
before_validation_on_create :auto_geocode_address
end
end
end
# this is the callback for auto_geocoding
def auto_geocode_address
address=self.send(auto_geocode_field)
geo=GeoKit::Geocoders::MultiGeocoder.geocode(address)
if geo.success
self.send("#{lat_column_name}=", geo.lat)
self.send("#{lng_column_name}=", geo.lng)
else
errors.add(auto_geocode_field, auto_geocode_error_message)
end
geo.success
end
# Instance methods to mix into ActiveRecord.
module InstanceMethods #:nodoc:
# Mix class methods into module.
def self.included(base) # :nodoc:
base.extend SingletonMethods
end
# Class singleton methods to mix into ActiveRecord.
module SingletonMethods # :nodoc:
# Extends the existing find method in potentially two ways:
# - If a mappable instance exists in the options, adds a distance column.
# - If a mappable instance exists in the options and the distance column exists in the
# conditions, substitutes the distance sql for the distance column -- this saves
# having to write the gory SQL.
def find(*args)
prepare_for_find_or_count(:find, args)
super(*args)
end
# Extends the existing count method by:
# - If a mappable instance exists in the options and the distance column exists in the
# conditions, substitutes the distance sql for the distance column -- this saves
# having to write the gory SQL.
def count(*args)
prepare_for_find_or_count(:count, args)
super(*args)
end
# Finds within a distance radius.
def find_within(distance, options={})
options[:within] = distance
find(:all, options)
end
alias find_inside find_within
# Finds beyond a distance radius.
def find_beyond(distance, options={})
options[:beyond] = distance
find(:all, options)
end
alias find_outside find_beyond
# Finds according to a range. Accepts inclusive or exclusive ranges.
def find_by_range(range, options={})
options[:range] = range
find(:all, options)
end
# Finds the closest to the origin.
def find_closest(options={})
find(:nearest, options)
end
alias find_nearest find_closest
# Finds the farthest from the origin.
def find_farthest(options={})
find(:farthest, options)
end
# Finds within rectangular bounds (sw,ne).
def find_within_bounds(bounds, options={})
options[:bounds] = bounds
find(:all, options)
end
# counts within a distance radius.
def count_within(distance, options={})
options[:within] = distance
count(options)
end
alias count_inside count_within
# Counts beyond a distance radius.
def count_beyond(distance, options={})
options[:beyond] = distance
count(options)
end
alias count_outside count_beyond
# Counts according to a range. Accepts inclusive or exclusive ranges.
def count_by_range(range, options={})
options[:range] = range
count(options)
end
# Finds within rectangular bounds (sw,ne).
def count_within_bounds(bounds, options={})
options[:bounds] = bounds
count(options)
end
# Returns the distance calculation to be used as a display column or a condition. This
# is provide for anyone wanting access to the raw SQL.
def distance_sql(origin, units=default_units, formula=default_formula)
case formula
when :sphere
sql = sphere_distance_sql(origin, units)
when :flat
sql = flat_distance_sql(origin, units)
end
sql
end
private
# Prepares either a find or a count action by parsing through the options and
# conditionally adding to the select clause for finders.
def prepare_for_find_or_count(action, args)
options = defined?(args.extract_options!) ? args.extract_options! : extract_options_from_args!(args)
# Obtain items affecting distance condition.
origin = extract_origin_from_options(options)
units = extract_units_from_options(options)
formula = extract_formula_from_options(options)
bounds = extract_bounds_from_options(options)
# if no explicit bounds were given, try formulating them from the point and distance given
bounds = formulate_bounds_from_distance(options, origin, units) unless bounds
# Apply select adjustments based upon action.
add_distance_to_select(options, origin, units, formula) if origin && action == :find
# Apply the conditions for a bounding rectangle if applicable
apply_bounds_conditions(options,bounds) if bounds
# Apply distance scoping and perform substitutions.
apply_distance_scope(options)
substitute_distance_in_conditions(options, origin, units, formula) if origin && options.has_key?(:conditions)
# Order by scoping for find action.
apply_find_scope(args, options) if action == :find
# Unfortunatley, we need to do extra work if you use an :include. See the method for more info.
handle_order_with_include(options,origin,units,formula) if options.include?(:include) && options.include?(:order) && origin
# Restore options minus the extra options that we used for the
# GeoKit API.
args.push(options)
end
# If we're here, it means that 1) an origin argument, 2) an :include, 3) an :order clause were supplied.
# Now we have to sub some SQL into the :order clause. The reason is that when you do an :include,
# ActiveRecord drops the psuedo-column (specificically, distance) which we supplied for :select.
# So, the 'distance' column isn't available for the :order clause to reference when we use :include.
def handle_order_with_include(options, origin, units, formula)
# replace the distance_column_name with the distance sql in order clause
options[:order].sub!(distance_column_name, distance_sql(origin, units, formula))
end
# Looks for mapping-specific tokens and makes appropriate translations so that the
# original finder has its expected arguments. Resets the the scope argument to
# :first and ensures the limit is set to one.
def apply_find_scope(args, options)
case args.first
when :nearest, :closest
args[0] = :first
options[:limit] = 1
options[:order] = "#{distance_column_name} ASC"
when :farthest
args[0] = :first
options[:limit] = 1
options[:order] = "#{distance_column_name} DESC"
end
end
# If it's a :within query, add a bounding box to improve performance.
# This only gets called if a :bounds argument is not otherwise supplied.
def formulate_bounds_from_distance(options, origin, units)
distance = options[:within] if options.has_key?(:within)
distance = options[:range].last-(options[:range].exclude_end?? 1 : 0) if options.has_key?(:range)
if distance
res=GeoKit::Bounds.from_point_and_radius(origin,distance,:units=>units)
else
nil
end
end
# Replace :within, :beyond and :range distance tokens with the appropriate distance
# where clauses. Removes these tokens from the options hash.
def apply_distance_scope(options)
distance_condition = "#{distance_column_name} <= #{options[:within]}" if options.has_key?(:within)
distance_condition = "#{distance_column_name} > #{options[:beyond]}" if options.has_key?(:beyond)
distance_condition = "#{distance_column_name} >= #{options[:range].first} AND #{distance_column_name} <#{'=' unless options[:range].exclude_end?} #{options[:range].last}" if options.has_key?(:range)
[:within, :beyond, :range].each { |option| options.delete(option) } if distance_condition
options[:conditions]=augment_conditions(options[:conditions],distance_condition) if distance_condition
end
# This method lets you transparently add a new condition to a query without
# worrying about whether it currently has conditions, or what kind of conditions they are
# (string or array).
#
# Takes the current conditions (which can be an array or a string, or can be nil/false),
# and a SQL string. It inserts the sql into the existing conditions, and returns new conditions
# (which can be a string or an array
def augment_conditions(current_conditions,sql)
if current_conditions && current_conditions.is_a?(String)
res="#{current_conditions} AND #{sql}"
elsif current_conditions && current_conditions.is_a?(Array)
current_conditions[0]="#{current_conditions[0]} AND #{sql}"
res=current_conditions
else
res=sql
end
res
end
# Alters the conditions to include rectangular bounds conditions.
def apply_bounds_conditions(options,bounds)
sw,ne=bounds.sw,bounds.ne
lng_sql= bounds.crosses_meridian? ? "(#{qualified_lng_column_name}<#{sw.lng} OR #{qualified_lng_column_name}>#{ne.lng})" : "#{qualified_lng_column_name}>#{sw.lng} AND #{qualified_lng_column_name}<#{ne.lng}"
bounds_sql="#{qualified_lat_column_name}>#{sw.lat} AND #{qualified_lat_column_name}<#{ne.lat} AND #{lng_sql}"
options[:conditions]=augment_conditions(options[:conditions],bounds_sql)
end
# Extracts the origin instance out of the options if it exists and returns
# it. If there is no origin, looks for latitude and longitude values to
# create an origin. The side-effect of the method is to remove these
# option keys from the hash.
def extract_origin_from_options(options)
origin = options.delete(:origin)
res = normalize_point_to_lat_lng(origin) if origin
res
end
# Extract the units out of the options if it exists and returns it. If
# there is no :units key, it uses the default. The side effect of the
# method is to remove the :units key from the options hash.
def extract_units_from_options(options)
units = options[:units] || default_units
options.delete(:units)
units
end
# Extract the formula out of the options if it exists and returns it. If
# there is no :formula key, it uses the default. The side effect of the
# method is to remove the :formula key from the options hash.
def extract_formula_from_options(options)
formula = options[:formula] || default_formula
options.delete(:formula)
formula
end
def extract_bounds_from_options(options)
bounds = options.delete(:bounds)
bounds = GeoKit::Bounds.normalize(bounds) if bounds
end
# Geocode IP address.
def geocode_ip_address(origin)
geo_location = GeoKit::Geocoders::IpGeocoder.geocode(origin)
return geo_location if geo_location.success
raise GeoKit::Geocoders::GeocodeError
end
# Given a point in a variety of (an address to geocode,
# an array of [lat,lng], or an object with appropriate lat/lng methods, an IP addres)
# this method will normalize it into a GeoKit::LatLng instance. The only thing this
# method adds on top of LatLng#normalize is handling of IP addresses
def normalize_point_to_lat_lng(point)
res = geocode_ip_address(point) if point.is_a?(String) && /^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})?$/.match(point)
res = GeoKit::LatLng.normalize(point) unless res
res
end
# Augments the select with the distance SQL.
def add_distance_to_select(options, origin, units=default_units, formula=default_formula)
if origin
distance_selector = distance_sql(origin, units, formula) + " AS #{distance_column_name}"
selector = options.has_key?(:select) && options[:select] ? options[:select] : "*"
options[:select] = "#{selector}, #{distance_selector}"
end
end
# Looks for the distance column and replaces it with the distance sql. If an origin was not
# passed in and the distance column exists, we leave it to be flagged as bad SQL by the database.
# Conditions are either a string or an array. In the case of an array, the first entry contains
# the condition.
def substitute_distance_in_conditions(options, origin, units=default_units, formula=default_formula)
original_conditions = options[:conditions]
condition = original_conditions.is_a?(String) ? original_conditions : original_conditions.first
pattern = Regexp.new("\s*#{distance_column_name}(\s<>=)*")
condition = condition.gsub(pattern, distance_sql(origin, units, formula))
original_conditions = condition if original_conditions.is_a?(String)
original_conditions[0] = condition if original_conditions.is_a?(Array)
options[:conditions] = original_conditions
end
# Returns the distance SQL using the spherical world formula (Haversine). The SQL is tuned
# to the database in use.
def sphere_distance_sql(origin, units)
lat = deg2rad(origin.lat)
lng = deg2rad(origin.lng)
multiplier = units_sphere_multiplier(units)
case connection.adapter_name.downcase
when "mysql"
sql=<<-SQL_END
(ACOS(least(1,COS(#{lat})*COS(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*COS(RADIANS(#{qualified_lng_column_name}))+
COS(#{lat})*SIN(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*SIN(RADIANS(#{qualified_lng_column_name}))+
SIN(#{lat})*SIN(RADIANS(#{qualified_lat_column_name}))))*#{multiplier})
SQL_END
when "postgresql"
sql=<<-SQL_END
(ACOS(least(1,COS(#{lat})*COS(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*COS(RADIANS(#{qualified_lng_column_name}))+
COS(#{lat})*SIN(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*SIN(RADIANS(#{qualified_lng_column_name}))+
SIN(#{lat})*SIN(RADIANS(#{qualified_lat_column_name}))))*#{multiplier})
SQL_END
else
sql = "unhandled #{connection.adapter_name.downcase} adapter"
end
end
# Returns the distance SQL using the flat-world formula (Phythagorean Theory). The SQL is tuned
# to the database in use.
def flat_distance_sql(origin, units)
lat_degree_units = units_per_latitude_degree(units)
lng_degree_units = units_per_longitude_degree(origin.lat, units)
case connection.adapter_name.downcase
when "mysql"
sql=<<-SQL_END
SQRT(POW(#{lat_degree_units}*(#{origin.lat}-#{qualified_lat_column_name}),2)+
POW(#{lng_degree_units}*(#{origin.lng}-#{qualified_lng_column_name}),2))
SQL_END
when "postgresql"
sql=<<-SQL_END
SQRT(POW(#{lat_degree_units}*(#{origin.lat}-#{qualified_lat_column_name}),2)+
POW(#{lng_degree_units}*(#{origin.lng}-#{qualified_lng_column_name}),2))
SQL_END
else
sql = "unhandled #{connection.adapter_name.downcase} adapter"
end
end
end
end
end
end
# Extend Array with a sort_by_distance method.
# This method creates a "distance" attribute on each object,
# calculates the distance from the passed origin,
# and finally sorts the array by the resulting distance.
class Array
def sort_by_distance_from(origin, opts={})
distance_attribute_name = opts.delete(:distance_attribute_name) || 'distance'
self.each do |e|
e.class.send(:attr_accessor, distance_attribute_name) if !e.respond_to? "#{distance_attribute_name}="
e.send("#{distance_attribute_name}=", origin.distance_to(e,opts))
end
self.sort!{|a,b|a.send(distance_attribute_name) <=> b.send(distance_attribute_name)}
end
end