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))
Returns a new hash with only the given keys.
# File 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
Replaces the hash with only the given keys. Returns a hash contained the removed key/value pairs
{:a => 1, :b => 2, :c => 3, :d => 4}.slice!(:a, :b) # => {:c => 3, :d =>4}
# File lib/active_support/core_ext/hash/slice.rb, line 29 def slice!(*keys) keys = keys.map! { |key| convert_key(key) } if respond_to?(:convert_key) omit = slice(*self.keys - keys) hash = slice(*keys) replace(hash) omit end
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