Gemfile

gem 'geokit'

geokit.rb

# This is an initialiser which sets up GeoKit

if defined? Geokit
	Geokit::default_units = :miles
	Geokit::default_formula = :sphere
	Geokit::Geocoders::request_timeout = 3
	Geokit::Geocoders::proxy_addr = nil
	Geokit::Geocoders::proxy_port = nil
	Geokit::Geocoders::proxy_user = nil
	Geokit::Geocoders::proxy_pass = nil
	Geokit::Geocoders::yahoo = 'REPLACE_WITH_YOUR_YAHOO_KEY'
	Geokit::Geocoders::google = 'REPLACE_WITH_YOUR_GOOGLE_KEY'
	Geokit::Geocoders::geocoder_us = false 
	Geokit::Geocoders::geocoder_ca = false
	Geokit::Geocoders::provider_order = [:google, :us]
	Geokit::Geocoders::ip_provider_order = [:geo_plugin, :ip]
end

index.html.haml

You'll then have access to the GeoLoc object where you can access
location data such as #lat and #lng.

= debug @tour_date.geo.lat
= debug @tour_date.geo.lng

tour_date.rb

# Here is an example of a simple GeoKit logging function.
# If a query is present we try to find a location from it
# and return an unsaved record.

class TourDate < ActiveRecord::Base
  validates :geo, :presence => true
  serialize :geo, Geokit::GeoLoc
  
  class << self
    def log(params = {})
      if query = params.delete(:query)
        location = Geokit::Geocoders::MultiGeocoder.geocode(query)
        params.merge!(:geo => location) if location.success
      end
      
      new(params)
    end
  end
end

tour_dates_controller.rb

# The tour dates controller expects a params hash just
# like a standard Rails form. If the query isn't present
# we can fall back to an alternative, such as the requesting IP address.

class TourDatesController < ApplicationController
  
  def create
    unless params[:tour_date][:query].present?
      params[:tour_date][:query] = request.ip
    end
    
    @tour_date = TourDate.log(params[:tour_date])
    
    if @tour_date.save
      redirect_to tour_date_path(@tour_date), :notice => "Successfully created tour date."
    else
      render :new
    end
  end
end