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Useful Iterators and Methods for Ruby on Rails

By Barry Burd

Part of Ruby on Rails For Dummies Cheat Sheet

When you want to travel through the items in a database you created with Ruby on Rails, knowing the iterators to use is key. The following table shows helpful iterators and methods:

[1, 2, 3].each { } => [1, 2, 3]
[1, nil, nil, 2, 3, nil].compact { } => [1, 2, 3]
[1, 2, 3].delete_if { |x| x >= 3 } => [1, 2]
[1, 2, 3].collect { |x| x + 1 } => [2, 3, 4]
[1, 2, 3].find_all { |x| x % 2 == 1 } => [1, 3]
[1, 2, 3].reject { |x| x % 2 == 1 } => [2]
[2, 5, 1, 0, 7].sort => [0, 1, 2, 5, 7]
[2, 5, 1, 0, 7].max => 7
[1, [2, 3]].flatten => [1, 2, 3]
[1, 2, 3].empty? => false
[].empty? => true
[0, 5, 9].length => 3
[1, 2, 3].include?(2) => true
[1, 2, 3].include?(16) => false
[1, 2, 3].reverse => [3, 2, 1]