test/fixtures/fr_users.yml @@ -9,13 +9,20 @@ module GreenRiver #:nodoc: # Item.random(5, :conditions => ...) def random(*args) limit = args.first - options = args.last.is_a?(::Hash) ? pop : {} - options[:select] = "id" - options.delete(:limit) - options.delete(:order) - sql = construct_finder_sql(options) - all_ids = connection.select_all(sql, "#{name} Load").collect!{|r| r['id']} - find(Array.new(limit){|i| all_ids.delete_at(rand(all_ids.length - 1))}) + options = args.last.is_a?(::Hash) ? args.pop : {} + # if only one row is requested, use the strategy of getting the size of the + # result set, and then in a second query offset by a random int of that + if limit == 1 + result_size = count(options) + find(:first, options.merge(:offset => rand(result_size - 1))) + else + options[:select] = "id" + options.delete(:limit) + options.delete(:order) + sql = construct_finder_sql(options) + all_ids = connection.select_all(sql, "#{name} Load").collect!{|r| r['id']} + find(Array.new(limit){|i| all_ids.delete_at(rand(all_ids.length - 1))}) + end end end end lib/green_river/find_random.rb @@ -1,20 +1,29 @@ require 'test_helper' -class User < ActiveRecord::Base +class FrUser < ActiveRecord::Base end class FindRandomTest < Test::Unit::TestCase - fixtures :users + fixtures :fr_users def test_size_of_found_collection - assert_equal 4, User.random(4).size + assert_equal 4, FrUser.random(4).size end def test_found_collection_random srand(14) - rand_users = User.random(3) + rand_users = FrUser.random(3) assert_equal 'matilda', rand_users[0].login assert_equal 'silvia', rand_users[1].login assert_equal 'leon', rand_users[2].login end + + def test_finding_single_random_row + srand(8) + assert_equal 'patricia', FrUser.random(1).login + end + def test_finding_single_random_row_with_conditions + srand(9) + assert_equal 'matilda', FrUser.random(1, :conditions => 'login LIKE "%il%"').login + end end test/find_random_test.rb @@ -1,5 +1,5 @@ ActiveRecord::Schema.define(:version => 1) do - create_table "users", :force => true do |t| + create_table "fr_users", :force => true do |t| t.column "login", :string end end test/schema.rb test/fixtures/users.yml 66a2c4901f8129f7a25c7242c24acea8318ced64 Ben Tucker ben@btucker.net http://github.com/btucker/find_random/commit/c437d95bcf0fe9fbbaad714fae92e5397b1f1d21 c437d95bcf0fe9fbbaad714fae92e5397b1f1d21 2008-03-03T14:52:47-08:00 2008-03-03T14:52:47-08:00 use more effective strategy when only one result requested 54e35d8f69d50b563cadef33d3bdf5953abec7bb Ben Tucker ben@btucker.net