Ruby on Rails：ActiveRecord ::连接未建立

Question

I'm trying to enable mySQL for my Ruby on Rails application. I generated a model for Project in Rails, used bundle exec rake db:migrate , and it added all fields required to myapp_dev database (mySQL). But when I go to localhost:3000/projects , I get this error:

ActiveRecord::ConnectionNotEstablished

activerecord (3.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:374:in `retrieve_connection'
activerecord (3.2.0) lib/active_record/connection_adapters/abstract/connection_specification.rb:168:in `retrieve_connection'
activerecord (3.2.0) lib/active_record/connection_adapters/abstract/connection_specification.rb:142:in `connection'
activerecord (3.2.0) lib/active_record/query_cache.rb:67:in `rescue in call'
activerecord (3.2.0) lib/active_record/query_cache.rb:61:in `call'
activerecord (3.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.0) lib/active_support/callbacks.rb:405:in `_run__93413930__call__216979767__callbacks'
activesupport (3.2.0) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.0) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.0) lib/rails/rack/logger.rb:26:in `call_app'
railties (3.2.0) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.0) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.0) lib/action_dispatch/middleware/static.rb:53:in `call'
railties (3.2.0) lib/rails/engine.rb:479:in `call'
railties (3.2.0) lib/rails/application.rb:220:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.0) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
/usr/share/ruby-rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/usr/share/ruby-rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/usr/share/ruby-rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

What is the problem here? Here is my database.yml

development:
  adapter: mysql
  encoding: utf8
  database: myapp_dev
  username: root
  password: root
  host: localhost

Answer 1

Seems like, your MySql db connection is not working, try to login to your my sql server with following command

mysql -uroot -proot myapp_dev

Make sure this works, if this works your app also should be able to access the DB, If you get any error, posting the error here will get someone to help you

cheers

Answer 2

Try putting 'dev' section on the top of database.yml:

dev:
  adapter: mysql
  encoding: utf8
  database: myapp_dev
  username: root
  password: root
  host: localhost

and leave 'development' section as it is.