Error while running the ruby server says connection not established - ruby-on-rails

Question

I am using rails 3.2.9 and database of postgres.
I have edited database.yml file in the following way and also gem pg was also installed..
When I run bundle command it shows pg gem in that list. But if I run the rails server command it shows the active connection not established.
development:
adapter: postgresql
database: db_pchamara/development.postgresql
pool: 5
username: database username
password: password
host: database ip address
test:
adapter: postgresql
database: database name/test.postgresql
pool: 5
username:database username
password: password
production:
adapter: postgresql
database: database name/production.postgresql
pool: 5
username: database username
password: password
But when I run command rails server it shows as follows:
[root#vdimc04 my_app]# rails server
=> Booting WEBrick
=> Rails 3.2.9 application starting in development on http
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2012-12-06 12:49:35] INFO WEBrick 1.3.1
[2012-12-06 12:49:35] INFO ruby 1.9.3 (2012-11-10) [i686-linux]
[2012-12-06 12:49:35] INFO WEBrick::HTTPServer#start: pid=7536 port=3000
Started GET "/assets/rails.png" for 127.0.0.1 at 2012-12-06 12:49:53 +0530
ActiveRecord::ConnectionNotEstablished (ActiveRecord::ConnectionNotEstablished):
activerecord (3.2.9) lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
activerecord (3.2.9) lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
activerecord (3.2.9) lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
activerecord (3.2.9) lib/active_record/query_cache.rb:67:in `rescue in call'
activerecord (3.2.9) lib/active_record/query_cache.rb:61:in `call'
activerecord (3.2.9) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.9) lib/active_support/callbacks.rb:405:in `_run__626989987__call__446659449__callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.9) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.9) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.9) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.9) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.9) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.9) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.9) 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 (3.2.9) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.9) lib/rails/engine.rb:479:in `call'
railties (3.2.9) lib/rails/application.rb:223:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.9) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p327/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p327/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/usr/local/rvm/rubies/ruby-1.9.3-p327/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
Rendered /usr/local/rvm/gems/ruby-1.9.3-p327/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.3ms)
Rendered /usr/local/rvm/gems/ruby-1.9.3-p327/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (3.0ms)
Rendered /usr/local/rvm/gems/ruby-1.9.3-p327/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (29.4ms)
Please help me to solve this problem.

Answer 1

The problem is in the configuration of the file:
development:
adapter: postgresql
database: db_pchamara/development.postgresql
pool: 5
username: database username
password: password
host: database ip address
change it to:
development:
adapter: postgresql
database: name_of_database
pool: 5
username: db_user
password: db_pass
host: db_host
most of the time db_host is just localhost
also, make sure you can connect with psql before you actually try to connect with rails.
if the db doesn't exist, you have to create the db with
rake db:create
cheers ;)