Gem versions and constraints in Ruby - Mini Project: Build & Apply

Gem versions and constraints

📖 Scenario: You are managing a Ruby project that uses gems (libraries). You want to specify exact versions and version constraints for gems in your Gemfile to ensure your project uses the right gem versions.

🎯 Goal: Learn how to write gem version constraints in a Gemfile by specifying exact versions, minimum versions, and version ranges.

📋 What You'll Learn

Create a Gemfile with gem entries

Specify an exact version for one gem

Specify a minimum version constraint for another gem

Specify a version range constraint for a third gem

Print the contents of the Gemfile to verify

💡 Why This Matters

🌍 Real World

Ruby developers use Gemfiles to manage gem versions so their apps run reliably on all machines.

💼 Career

Understanding gem version constraints is essential for Ruby developers, DevOps engineers, and anyone maintaining Ruby applications.

1

Create a Gemfile with three gems

Create a file called Gemfile and add these three gems exactly as shown: gem 'rails', gem 'nokogiri', and gem 'puma' without any version constraints.

Ruby

# Create a Gemfile with three gems: rails, nokogiri, and puma
# Your code here

Need a hint?

Just write each gem line exactly as gem 'gem_name' without versions.

2

Add an exact version constraint for rails

Modify the Gemfile to specify that rails must be exactly version 7.0.4. Keep the other gems unchanged.

Ruby

gem 'rails'
gem 'nokogiri'
gem 'puma'
# Change rails to version '7.0.4' exactly
# Your code here

Need a hint?

Use gem 'rails', '7.0.4' to specify exact version.

3

Add a minimum version constraint for nokogiri

Modify the Gemfile to specify that nokogiri must be version 1.13 or higher. Keep the other gems unchanged.

Ruby

gem 'rails', '7.0.4'
gem 'nokogiri'
gem 'puma'
# Change nokogiri to version '>= 1.13'
# Your code here

Need a hint?

Use gem 'nokogiri', '>= 1.13' to specify minimum version.

4

Add a version range constraint for puma and print Gemfile

Modify the Gemfile to specify that puma must be between versions 5.0 and 5.5 inclusive. Then write Ruby code to read and print the contents of the Gemfile.

Ruby

gem 'rails', '7.0.4'
gem 'nokogiri', '>= 1.13'
gem 'puma'
# Change puma to version '>= 5.0', '<= 5.5'
# Then read and print Gemfile contents
# Your code here

Need a hint?

Use gem 'puma', '>= 5.0', '<= 5.5' for version range.
Use puts File.read('Gemfile') to print the file.