Rails 6 adds Array#extract!

Amit Choudhary

By Amit Choudhary

on June 24, 2019

This blog is part of our  Rails 6 series.

Rails 6 added extract! on Array class. extract! removes and returns the elements for which the given block returns true.

extract! is different from reject! in the way that reject! returns the array after removing the elements whereas extract! returns removed elements from the array.

Let's checkout how it works.

Rails 6.0.0.beta2

Let's pluck all the user emails and then extract emails which include gmail.com.

1
2> > emails = User.pluck(:email)
3> > SELECT "users"."email" FROM "users"
4
5=> ["amit.choudhary@bigbinary.com", "amit@gmail.com", "mark@gmail.com", "sam@gmail.com"]
6
7> > emails.extract! { |email| email.include?('gmail.com') }
8
9=> ["amit@gmail.com", "mark@gmail.com", "sam@gmail.com"]
10
11> > emails
12
13=> ["amit.choudhary@bigbinary.com"]
14
15> > emails = User.pluck(:email)
16> > SELECT "users"."email" FROM "users"
17
18=> ["amit.choudhary@bigbinary.com", "amit@gmail.com", "mark@gmail.com", "sam@gmail.com"]
19
20> > emails.reject! { |email| email.include?('gmail.com') }
21
22=> ["amit.choudhary@bigbinary.com"]
23
24> > emails
25
26=> ["amit.choudhary@bigbinary.com"]

Here is the relevant pull request.