title: rails mysql adapter error
body: <p>I'm having trouble finding a solution to this problem. I'm getting the error</p>
  
  <blockquote>
    <p>Please install the mysql adapter: 'gem install activerecord-mysql-adapter'</p>
  </blockquote>
  
  <p>when I specify either <code>ruby-mysql</code> or <code>mysql2</code> in my <code>Gemfile</code>. This has only happened since I've upgraded to Rails 3.1.0-rc1. I'm running OSX 10.6, Ruby 1.9.2.</p>
  
  <pre><code>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 &lt;class:Railtie&gt;'
  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 `&lt;top (required)&gt;'
  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 &lt;class:Railtie&gt;'
  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 `&lt;top (required)&gt;'
  from script/rails:6:in `require'
  from script/rails:6:in `&lt;main&gt;'
  </code></pre>
  
  <p>Here is the <code>gem env</code> output</p>
  
  <pre><code>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 =&gt; true
     - :verbose =&gt; true
     - :benchmark =&gt; false
     - :backtrace =&gt; false
     - :bulk_threshold =&gt; 1000
     - :sources =&gt; ["http://gems.rubyforge.org/", "http://gems.github.com"]
  - REMOTE SOURCES:
     - http://gems.rubyforge.org/
     - http://gems.github.com
  </code></pre>