Rails 4 Action Controller: Exception caught Mysql2::Error

Question

Rails 4 Action Controller: Exception caught Mysql2::Error

Trying to open "Lynda.com Essential Ruby on rails 4" exercise files app on localhost:3000/ and this is what i get:

Mysql2::Error
Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

Thanks!!

Update: 25/01 These are my logs:

Started GET "/" for 127.0.0.1 at 2014-01-22 15:46:18 +0200

Mysql2::Error (Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)):
  mysql2 (0.3.13) lib/mysql2/client.rb:58:in `connect'
  mysql2 (0.3.13) lib/mysql2/client.rb:58:in `initialize'
  activerecord (4.0.0) lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `new'
  activerecord (4.0.0) lib/active_record/connection_adapters/mysql2_adapter.rb:18:in     `mysql2_connection'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:440:in `new_connection'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:450:in `checkout_new_connection'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:421:in `acquire_connection'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:356:in `block in checkout'
   /home/ggeorgiev/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/monitor.rb:211:in `    mon_synchronize'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:355:in `checkout'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract    /connection_pool.rb:265:in `block in connection'
  /home/ggeorgiev/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/monitor.rb:211:in     `mon_synchronize'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'
  activerecord (4.0.0) lib/active_record/connection_handling.rb:79:in `retrieve_connection'
  activerecord (4.0.0) lib/active_record/connection_handling.rb:53:in `connection'
  activerecord (4.0.0) lib/active_record/migration.rb:792:in `current_version'
  activerecord (4.0.0) lib/active_record/migration.rb:800:in `needs_migration?'
  activerecord (4.0.0) lib/active_record/migration.rb:379:in `check_pending!'
  activerecord (4.0.0) lib/active_record/migration.rb:366:in `call'
  actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.0.0) lib/active_support/callbacks.rb:373:in      `_run__4564087381787545460__call__callbacks'
  activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks'
  actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call'
  actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
  actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call'
  activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged'
  activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged'
  activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged'
   railties (4.0.0) lib/rails/rack/logger.rb:21:in `call'
   actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
   rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
   rack (1.5.2) lib/rack/runtime.rb:17:in `call'
   activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
   rack (1.5.2) lib/rack/lock.rb:17:in `call'
   actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call'
  railties (4.0.0) lib/rails/engine.rb:511:in `call'
  railties (4.0.0) lib/rails/application.rb:97:in `call'
   rack (1.5.2) lib/rack/lock.rb:17:in `call'
   rack (1.5.2) lib/rack/content_length.rb:14:in `call'
   rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
   /home/ggeorgiev/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/webrick/httpserver.rb:138:in     `service'
  /home/ggeorgiev/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/webrick/httpserver.rb:94:in     `run'
          /home/ggeorgiev/.rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/webrick/server.rb:295:in      `block in start_thread'

    Rendered /home/ggeorgiev/.rvm/gems/ruby-2.0.0-p353/gems/actionpack-4.0.0/lib    /action_dispatch/middleware/templates/rescues/_source.erb (0.7ms)
    Rendered /home/ggeorgiev/.rvm/gems/ruby-2.0.0-p353/gems/actionpack-4.0.0/lib    /action_dispatch/middleware/templates/rescues/_trace.erb (1.6ms)
    Rendered /home/ggeorgiev/.rvm/gems/ruby-2.0.0-p353/gems/actionpack-4.0.0/lib    /action_dispatch/middleware/templates/rescues/_request_and_response.erb (1.1ms)
    Rendered /home/ggeorgiev/.rvm/gems/ruby-2.0.0-p353/gems/actionpack-4.0.0/lib    /action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (16.2ms)

Answer 1

The server has not started. You could start it from System Preference.

System Preference -> Mysql -> Start Server.

Or else you could start it from the terminal. The command varies depending on how you installed MySQL. Try this first:

sudo /Library/StartupItems/MySQLCOM/MySQLCOM start

If that fails:

cd /usr/local/mysql
sudo ./bin/mysqld_safe
(Enter your password, if necessary)
(Press Control-Z)
bg

If that doesn't work then try below

mysql.server start
mysqladmin variables | grep socket

For me it gave,

| socket                                                 | /tmp/mysql.sock

Then add a line to your config/database.yml

development:
 adapter: mysql2
 host: localhost
 username: root
 password: xxxx
 database: xxxx
 socket: /tmp/mysql.sock

Hope that solves your problem.