sepastian

# Given an array of arrays s = [ [1,2,3], [4,5,6], ... ]
# compute the Cartesian product among the elements of s.

require 'pp'

s = [[1, 2], [3, 4, 5], [6, 7, 8, 9]]
pp s[1..-1].inject(s[0]){ |m,v| m = m.product(v).map(&:flatten) }
[[1, 3, 6],
 [1, 3, 7],
 [1, 3, 8],

mlanett

HTTP status code symbols for Rails

Thanks to Cody Fauser for this list of HTTP responce codes and their Ruby on Rails symbol mappings.

Status Code Symbol
1xx Informational
100 :continue
101 :switching_protocols
102 :processing

ProGM

Arel Cheatsheet on Steroids

A (more) complete cheatsheet for Arel, including NamedFunction functions, raw SQL and window functions.

Tables

posts = Arel::Table.new(:posts)
posts = Post.arel_table # ActiveRecord

Table alias