rails mysql adapter error

Question

I'm having trouble finding a solution to this problem. I'm getting the error

Please install the mysql adapter: 'gem install activerecord-mysql-adapter'

when I specify either ruby-mysql or mysql2 in my Gemfile. This has only happened since I've upgraded to Rails 3.1.0-rc1. I'm running OSX 10.6, Ruby 1.9.2.

cody$ rails c
/Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:71:in `rescue in establish_connection': Please install the mysql adapter: `gem install activerecord-mysql-adapter` (mysql is not part of the bundle. Add it to Gemfile.) (RuntimeError)
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:68:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:60:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/connection_adapters/abstract/connection_specification.rb:55:in `establish_connection'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/railtie.rb:69:in `block (2 levels) in <class:Railtie>'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:36:in `instance_eval'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:36:in `execute_hook'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:43:in `block in run_load_hooks'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:42:in `each'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.1.0.rc1/lib/active_support/lazy_load_hooks.rb:42:in `run_load_hooks'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/base.rb:2135:in `<top (required)>'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/activerecord-3.1.0.rc1/lib/active_record/railtie.rb:34:in `block in <class:Railtie>'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/railtie.rb:177:in `call'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/railtie.rb:177:in `block in load_console'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/railtie.rb:177:in `each'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/railtie.rb:177:in `load_console'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/application.rb:115:in `block in load_console'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/application/railties.rb:8:in `each'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/application/railties.rb:8:in `all'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/application.rb:115:in `load_console'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/commands/console.rb:26:in `start'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/commands/console.rb:8:in `start'
from /Users/cody/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.1.0.rc1/lib/rails/commands.rb:40:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

Here is the gem env output

cody$ gem env
RubyGems Environment:
- RUBYGEMS VERSION: 1.6.2
- RUBY VERSION: 1.9.2 (2011-02-18 patchlevel 180) [x86_64-darwin10.7.3]
- INSTALLATION DIRECTORY: /Users/cody/.rvm/gems/ruby-1.9.2-p180
- RUBY EXECUTABLE: /Users/cody/.rvm/rubies/ruby-1.9.2-p180/bin/ruby
- EXECUTABLE DIRECTORY: /Users/cody/.rvm/gems/ruby-1.9.2-p180/bin
- RUBYGEMS PLATFORMS:
  - ruby
  - x86_64-darwin-10
- GEM PATHS:
   - /Users/cody/.rvm/gems/ruby-1.9.2-p180
   - /Users/cody/.rvm/gems/ruby-1.9.2-p180@global
- GEM CONFIGURATION:
   - :update_sources => true
   - :verbose => true
   - :benchmark => false
   - :backtrace => false
   - :bulk_threshold => 1000
   - :sources => ["http://gems.rubyforge.org/", "http://gems.github.com"]
- REMOTE SOURCES:
   - http://gems.rubyforge.org/
   - http://gems.github.com

Answer 1

You'll have to change your config/database.yml to use the mysql2 adapter instead of mysql.

So replace:

adapter: mysql

With:

adapter: mysql2

Answer 2

I had to enforce the use of mysql2 gem version 0.2.7 and while trying to upgrade my rails 3.0.7 app to 3.1.0.rc1, I also noticed ,that you'll need the following new gems in your Gemfile, too:

gem 'mysql2', '< 0.3' # as stated above

# Asset template engines
gem 'json'
gem 'sass'
gem 'coffee-script'
gem 'uglifier'
# other required things for rails 3.1
gem 'jquery-rails'
gem 'mustang' # this is ONE execjs backend of many, and the only one that worked for me.

Tell me if that worked for you.

Answer 3

Fixed the problem by updating the gemfile for my app to identify mysql2 as part of the bundle.

To do this, navigate to the root of your app, run open gemfile

Add the line gem 'mysql2', '< 0.3.7' directly below the gem line for rails.

While in terminal at the root of your app, run bundle install

Run bundle show mysql2 to verify the bundle worked. You should be good to go with the adapter now.

My environment is Rails 3.1, MySql 5.5, Ruby 1.9.2.