Rails 4 - Gem::LoadError: Specified 'mysql2' for database adapter, but the gem is not loaded

Question

In my gemfile I have:

gem \'mysql2\'

My database.yml is as follows:

default: &default
  adapter: mysql2
  database: <         


        

Answer 1

Had same issue but adding source 'https://rubygems.org' to the top of gem file solved issue.

Steps:

add source 'https://rubygems.org' to your gem file. Comment out mysql2 gem and add gem 'mysql2', '~> 0.3.18' Run bundle install

Answer 2

Just a further update - the solution in the question is correct.

The 4th comment is worth taking note of:

This isn't a bug with mysql2, it's a problem with the requirement in the ActiveRecord adapter: http://github.com/rails/rails/issues/21544. This is fixed in rails master: https://github.com/rails/rails/commit/5da5e3772c32593ecf2f27b8865e81dcbe3af692

I was able to tie Rails 4.2.4 to the 4-2-stable branch and get it working with the latest mysql2:

gem 'rails', '~> 4.2.4', git: "git://github.com/rails/rails.git", branch: '4-2-stable'
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw] #-> Rails 4.1+

#DB
gem 'mysql2'

Answer 3

As a complete beginner i got confused on how to do this so I just did a trial check and finally got my server working , here is how i got it working .

get into the file of working directory("work") and from there get into the file of the app you created("sample_app")which has mysql 2 installed go to gem file ("Gemfile")edit gem 'mysql2' to gem 'mysql2', '~> 0.3.18'

now go back to cmd and run command "bundle install".

so the directory to edit file taking consideration of above files in brackets should be . "c\work\sample_app\Gemfile"

hope i was of some help .