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Rails 6 requires Ruby 2.5 or newer
Rails 6.0 was recently released.
As per rails/rails#34754, a Rails 6 app requires Ruby version 2.5 or newer.
Let's discuss what we need to know if we are dealing with Rails 6.
Ensuring a valid Ruby version is set while creating a new Rails 6 app
While creating a new Rails 6 app, we need to ensure that the current Ruby version in the shell is set to 2.5 or newer.
If it is set to an older version
then the same version will be used
by the rails new command
to
set the Ruby version in
.ruby-version and in Gemfile respectively
in the created Rails app.
1\$ ruby -v
2ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]
3
4\$ rails new meme-wizard
5create
6create README.md
7create Rakefile
8create .ruby-version
9create config.ru
10create .gitignore
11create Gemfile
12[...] omitted the rest of the output
13
14\$ cd meme-wizard && grep -C 2 -Rn -a "2.3.1" .
15./.ruby-version:1:2.3.1
16--
17--
18./Gemfile-2-git_source(:github) { |repo| "https://github.com/#{repo}.git" }
19./Gemfile-3-
20./Gemfile:4:ruby '2.3.1'
21./Gemfile-5-
22./Gemfile-6-# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
An easy fix for this
is to install a Ruby version 2.5 or newer
and
use that version prior to running the rails new command.
1\$ ruby -v
2ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]
3
4\$ rbenv local 2.6.0
5
6\$ ruby -v
7ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-darwin18]
8
9\$ rails new meme-wizard
10
11\$ cd meme-wizard && grep -C 2 -Rn -a "2.6.0" .
12./.ruby-version:1:2.6.0
13--
14--
15./Gemfile-2-git_source(:github) { |repo| "https://github.com/#{repo}.git" }
16./Gemfile-3-
17./Gemfile:4:ruby '2.6.0'
18./Gemfile-5-
19./Gemfile-6-# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
Upgrading an older Rails app to Rails 6
While upgrading an older Rails app to Rails 6,
we need to update the Ruby version to 2.5 or newer
in .ruby-version and Gemfile files respectively.
What else do we need to know?
Since
Ruby 2.5 has added Hash#slice method,
the extension method with the same name
defined by
activesupport/lib/active_support/core_ext/hash/slice.rb
has been
removed from Rails 6.
Similarly,
Rails 6 has also
removed
the extension methods
Hash#transform_values
and
Hash#transform_values!
from Active Support
in favor of the native methods with the same names
which exist in Ruby.
These methods were
introduced in Ruby 2.4 natively.
If we try to explicitly require
active_support/core_ext/hash/transform_values
then it would print a deprecation warning.
1
2> > require "active_support/core_ext/hash/transform_values"
3
4# DEPRECATION WARNING: Ruby 2.5+ (required by Rails 6) provides Hash#transform_values natively, so requiring active_support/core_ext/hash/transform_values is no longer necessary. Requiring it will raise LoadError in Rails 6.1. (called from irb_binding at (irb):1)
5
6=> true