Key and value checks for Ruby arrays and hashes

Posted on 23 May 2012

Array and Hash classes in ruby have a basic functionality for the keys and values presence checks. However if you need some more advanced features, like testing if array contains all or any of the keys, you'll probably write a inline method. Having more frienly methods and ability to not repeat yourself is a huge plus.

Here is a small snippet with core class extensions for Array and Hash:

class Array
  def include_all?(values)
    (values - self).empty?
  end

  def include_any?(values)
    (self & values).any?
  end
end

class Hash
  def include_all?(keys)
    self.keys.include_all?(keys)
  end

  def include_any?(keys)
    self.keys.include_any?(keys)
  end
end

Examples:

[1,2,3].include_any?([1,2])     # => true
[1,2,3].include_any?([4,5,6])   # => false
[1,2,3].include_all?([1,2,3,4]) # => true
[1,2,3].include_all?([1,2])     # => false

For hashes:

({'a' => 1, 'b' => 2}.include_any?(['a', 'b', 'c'])) # => true
({'a' => 1, :b => 2}.include_any?(['a', 'b', 'c']))  # => true
({'a' => 1, 'b' => 2}.include_all?(['a','b', 'c']))  # => true
({'a' => 1, 'b' => 2}.include_all?(['c']))           # => false