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