嗨，我是Ruby on Rails的新手。我已经安装了轨道，一切正常。然后，我将数据库从SQLITE更改为PostGre（因为Heroku不支持它），Git推到Heroku。一切都很好。但是，当我重新启动本地存储库时，它向我展示了（在本地存储库）：
用户〜：$ Rails Server
=> Booting WEBrick
=> Rails 3.2.13 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:1215:in `initialize': FATAL: role "roma" does not exist (PG::ConnectionBad)
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:1215:in `new'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:1215:in `connect'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:323:in `initialize'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:27:in `new'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/postgresql_adapter.rb:27:in `postgresql_connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
from /usr/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
from /usr/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
from /usr/lib/ruby/vendor_ruby/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
from /usr/lib/ruby/vendor_ruby/active_record/railtie.rb:88:in `block in <class:Railtie>'
from /usr/lib/ruby/vendor_ruby/rails/initializable.rb:30:in `instance_exec'
from /usr/lib/ruby/vendor_ruby/rails/initializable.rb:30:in `run'
from /usr/lib/ruby/vendor_ruby/rails/initializable.rb:55:in `block in run_initializers'
from /usr/lib/ruby/vendor_ruby/rails/initializable.rb:54:in `each'
from /usr/lib/ruby/vendor_ruby/rails/initializable.rb:54:in `run_initializers'
from /usr/lib/ruby/vendor_ruby/rails/application.rb:136:in `initialize!'
from /usr/lib/ruby/vendor_ruby/rails/railtie/configurable.rb:30:in `method_missing'
from /home/roma/Templates/first_app/config/environment.rb:5:in `<top (required)>'
from /home/roma/Templates/first_app/config.ru:3:in `require'
from /home/roma/Templates/first_app/config.ru:3:in `block in <main>'
from /usr/lib/ruby/vendor_ruby/rack/builder.rb:55:in `instance_eval'
from /usr/lib/ruby/vendor_ruby/rack/builder.rb:55:in `initialize'
from /home/roma/Templates/first_app/config.ru:in `new'
from /home/roma/Templates/first_app/config.ru:in `<main>'
from /usr/lib/ruby/vendor_ruby/rack/builder.rb:49:in `eval'
from /usr/lib/ruby/vendor_ruby/rack/builder.rb:49:in `new_from_string'
from /usr/lib/ruby/vendor_ruby/rack/builder.rb:40:in `parse_file'
from /usr/lib/ruby/vendor_ruby/rack/server.rb:277:in `build_app_and_options_from_config'
from /usr/lib/ruby/vendor_ruby/rack/server.rb:199:in `app'
from /usr/lib/ruby/vendor_ruby/rails/commands/server.rb:46:in `app'
from /usr/lib/ruby/vendor_ruby/rack/server.rb:314:in `wrapped_app'
from /usr/lib/ruby/vendor_ruby/rack/server.rb:250:in `start'
from /usr/lib/ruby/vendor_ruby/rails/commands/server.rb:70:in `start'
from /usr/lib/ruby/vendor_ruby/rails/commands.rb:55:in `block in <top (required)>'
from /usr/lib/ruby/vendor_ruby/rails/commands.rb:50:in `tap'
from /usr/lib/ruby/vendor_ruby/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
这可能是什么原因？对不起，英语不好。另外，这是我的数据库。yml文件
development:
adapter: postgresql
database: my_database_development
pool: 5
timeout: 5000
test:
adapter: postgresql
database: my_database_development
pool: 5
timeout: 5000
production:
adapter: postgresql
database: my_database_development
pool: 5
timeout: 5000
基于错误，您需要将用户 roma供您使用，以使您的导轨服务器使用以连接到数据库。您可以使用createuser来使您的用户在database.yml中定义。您可能需要先做：
sudo su - postgres
createuser -P -s -e {your_machine_username}
但是，只有当createuser使用普通createuser -P -s -e {user_defined_in_databaseyml}引发错误。
然后，您可以退出该用户（exit将删除su），并做：
createuser -P -s -e {user_defined_in_databaseyml}
然后，您应该能够 rails s很好（请确保您首先rake您的DB相关任务）。