Custom gem not loading into rails app - ruby-on-rails

Question

I've pushed gem into github & rubygems, but constants of that gem are not being loaded into rails app. Tried this by loading from multiple sources and results are like this:
rubygems = not loaded
github = not loaded
local path = loaded
Interesting things is that when I load with rubygems/github I can load constants with require 'module/gem_name'
The gemspecs looks fine to me:
# coding: utf-8
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'module/gem_name/version'
Gem::Specification.new do |spec|
spec.name = 'gem_name'
spec.version = Module::GemName::VERSION
spec.authors = ['Mike QWERTY']
spec.email = ['mike.qwerty#gamil.com']
spec.summary = 'some_desc'
spec.homepage = 'https://github.com/mike/gem-name'
spec.license = 'MIT'
if spec.respond_to?(:metadata)
spec.metadata['allowed_push_host'] = 'https://rubygems.org'
else
raise 'RubyGems 2.0 or newer is required to protect against public gem pushes.'
end
spec.files = `git ls-files -z`.split("\x0").reject do |f|
f.match(%r{^(test|spec|features)/})
end
spec.bindir = 'exe'
spec.executables = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
spec.require_paths = ['lib']
spec.required_ruby_version = '>= 2.4.0'
spec.add_runtime_dependency 'graphql', '>= 1.6.0'
spec.add_development_dependency 'bundler', '~> 1.14'
spec.add_development_dependency 'rake', '~> 10.0'
spec.add_development_dependency 'rspec', '~> 3.0'
end
And structure is:
lib/module/gem_name/stuff/others.rb
lib/module/gem_name/extras.rb
lib/module/gem_name.rb
Also, I've been working on this gem basing on other gem that has the same module name. But it loads correctly into app, if this matters.
Any ideas on this?

Answer 1

The gem is not autoloading because the main file (gem_name.rb) is not at the root of the lib directory. It is recommended that your Gem adhere to the following structure:
% tree
.
├── gem_name.gemspec
└── lib
├── gem_name
│ └── some_file.rb
│ └── other_file.rb
└── gem_name.rb
Yours has an extra module nesting. In your Rails application.rb you should see Bundler.require(*Rails.groups). What this method does is loop through every Gem in your Gemfile and call require gem_name. This works for Gem's that follow the convention mentioned above. Your gem does not - so the auto require being done by Bundler doesn't find the correct file to use.
See the Ruby Gems Guide for creating your own Gem for a bit more information on proper code organization.
If you don't want to change the structure of your application, either add
require "module/gem_name" in an initializer, or within the Gemfile:
gem "gem_name", require: "module/gem_name"