rails 5 mysql adapter issue - mysql

Question

Am trying to create a model in rails 5 and have installed mysql-community-server. Also I have installed both mysql and mysql2 gem's. But when i run rails generate model Book getting below error,
[root#server-linux library]# rails generate model Book
/root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `require': Could not load 'active_record/connection_adapters/mysql_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile. (LoadError)
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `block in require'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:259:in `load_dependency'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `require'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_handling.rb:53:in `establish_connection'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/railtie.rb:125:in `block (2 levels) in <class:Railtie>'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:45:in `block in run_load_hooks'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:44:in `each'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:44:in `run_load_hooks'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/base.rb:324:in `<module:ActiveRecord>'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/base.rb:24:in `<top (required)>'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:338:in `active_record_configured?'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:259:in `disconnect_database'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:97:in `preload'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:143:in `serve'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:131:in `block in run'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:125:in `loop'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:125:in `run'
from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application/boot.rb:19:in `<top (required)>'
from /root/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /root/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from -e:1:in `<main>'
[root#server-linux library]#
database.yaml:
[root#server-linux library]# cat config/database.yml
development:
adapter: mysql2
database: library_development
username: root
password: [password]
host: localhost
test:
adapter: mysql2
database: library_test
username: root
password: [password]
host: localhost
production:
adapter: mysql2
database: library_production
username: root
password: [password]
host: localhost
[root#server-linux library]#
Version details:
[root#server-linux library]# rails -v
Rails 5.0.0
[root#karthick-linux library]# gem list | grep mysql
activerecord-mysql-adapter (0.0.1)
mysql (2.9.1)
mysql2 (0.4.4)
[root#server-linux library]#
Even I created application with the command rails new library -d mysql
Any idea why its failing with mysql adapter connection.

Answer 1

Did you try installing bundler. I am guessing that mysql2 gem is installed for different version of ruby and not your current version of ruby. Try installing bundler first.
gem install bundler
bundle install
rails db:migrate
rails g model book
Also you won't need mysql gem, you can just delete it and use mysql2 as adapter in your database.yml file.

Answer 2

Check your Gem file
in your gem file find gem 'mysql2'
if not found please add gem 'mysql2' then run bundle install and restart server.