Sample code for Yahoo! local

CS290F Fall 2006 - UCSB Computer Science - Thorsten von Eicken

This is sample code for fetching restaurants in Isla Vista, CA. It is similar to what was shown in class. Stefan abstracted some things a bit more nicely.

Note that this example uses PostgreSQL. In any case, you will need to edit the parameters to ActiveRecord::Base.establish_connection

require 'pp'
require 'net/http'
require 'rubygems'
require_gem 'xml-simple'
require_gem 'activerecord'

# augment the standard classes String and Hash with the
# ability to encode themselves as URL-encoded query strings

class String
  def url_encode
    gsub(/[^a-zA-Z0-9\-_\.!~*'+]/n){|x| sprintf('%%%02x', x[0])}
  end
  def query_encode
    gsub(/ /,'+').url_encode
  end
end
class Hash
  def query_encode
    collect{|k,v| "#{k.to_s.url_encode}=#{v.to_s.query_encode}"}.join('&')
  end
end

# define how to make a web-API call to the Yahoo local search service

def yahoo_local_url args
  args[:appid] ||= 'ucsbcs290f'
  "http://api.local.yahoo.com/LocalSearchService/V1/localSearch?#{args.query_encode}"
end

url = yahoo_local_url :query=>'restaurants', :city=>'isla vista', :state=>'CA'
data = Net::HTTP.get_response(URI.parse(url)).body

# now parse the XML response and get the desired data out of it

results = XmlSimple.xml_in(data,'ForceArray'=>false)['Result'].collect do |r|
  { :name => r['Title'], :address => r['Address'], :url => r['ClickUrl'] }
end

# finally, connect to the database and save the results into it

ActiveRecord::Base.establish_connection(
  :adapter  => 'postgresql',
  :host     => 'localhost',
  :database => 'cs290f',
  :username => 'stefan'
)

ActiveRecord:: Base.logger = Logger.new(STDOUT)

class Restaurant < ActiveRecord::Base
  # for now, do nothing.
end

results.each {|x| Restaurant.new(x).save}

Under PostgreSQL, the database schema is the following:

create table restaurants (
  id serial primary key,
  name text,
  address text,
  url text
);

An alternative is to let ActiveRecord create the table (note the absence of the id field):

ActiveRecord::Migration.create_table(:restaurants, :force => true) do |t|
  t.column :name, :string
  t.column :address, :string
  t.column :url, :string
end