/ Ruby on Rails
/
method

extract!

v6.1.3.1 - Show latest stable - Class: Hash
extract!(*keys)
public

Removes and returns the key/value pairs matching the given keys.

hash = { a: 1, b: 2, c: 3, d: 4 }
hash.extract!(:a, :b) # => {:a=>1, :b=>2}
hash                  # => {:c=>3, :d=>4}

2Notes

without a bang

freemanoid321 · Sep 8, 2013

We can use hash#slice[http://api.rubyonrails.org/classes/Hash.html#method-i-slice] if we want an Hash#extract (without bang) like behavior.

Non-existent key semantics changed.

matthewtuck · Aug 13, 2014

For Rails 4.0, the behaviour of this has changed when you pass a key that isn't in the hash.

3.2 (undocumented):

{ a: 1, b: 2 }.extract!(:a, :x) # => {:a=>1, :x => nil}

4.0 (as per docs):

{ a: 1, b: 2 }.extract!(:a, :x) # => {:a=>1}

The 4.0 behaviour is now consistent with the behaviour of slice, the 3.2 behaviour was not.