Module: ActiveSupport::CoreExtensions::Hash::Slice

Included in:
Hash
Defined in:
lib/gems/activesupport-2.2.2/lib/active_support/core_ext/hash/slice.rb

Overview

Slice a hash to include only the given keys. This is useful for limiting an options hash to valid keys before passing to a method:

def search(criteria = {})
  assert_valid_keys(:mass, :velocity, :time)
end

search(options.slice(:mass, :velocity, :time))

If you have an array of keys you want to limit to, you should splat them:

valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))

Instance Method Summary collapse

Instance Method Details

#slice(*keys) ⇒ Object

Returns a new hash with only the given keys.



19
20
21
22
23
24
 
# File 'lib/gems/activesupport-2.2.2/lib/active_support/core_ext/hash/slice.rb', line 19

def slice(*keys)
  keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key)
  hash = self.class.new
  keys.each { |k| hash[k] = self[k] if has_key?(k) }
  hash
end

#slice!(*keys) ⇒ Object

Replaces the hash with only the given keys.



27
28
29
 
# File 'lib/gems/activesupport-2.2.2/lib/active_support/core_ext/hash/slice.rb', line 27

def slice!(*keys)
  replace(slice(*keys))
end