Conexion sinatra con postgres

[deivermora19]

hola, gracias por la respuesta soy nuevo con sinatra y no encuentro mucha documentación .

te muestro el error que da, es como de sintaxis

sly-019@slyDesktop:~/Escritorio/sinatra-blog$ ruby app.rb
/home/sly-019/.rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require': Could not load 'active_record/connection_adapters/sqlite_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile. (LoadError)
from /home/sly-019/.rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `block in require'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `require'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activerecord-4.2.1/lib/active_record/connection_adapters/connection_specification.rb:175:in `spec'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activerecord-4.2.1/lib/active_record/connection_handling.rb:50:in `establish_connection'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/sinatra-activerecord-2.0.6/lib/sinatra/activerecord.rb:43:in `database='
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/sinatra-1.4.6/lib/sinatra/base.rb:1216:in `set'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/sinatra-1.4.6/lib/sinatra/base.rb:1989:in `block (2 levels) in delegate'
from /home/sly-019/Escritorio/sinatra-blog/environments.rb:2:in `block in <top (required)>'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/sinatra-1.4.6/lib/sinatra/base.rb:1410:in `configure'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/sinatra-1.4.6/lib/sinatra/base.rb:1989:in `block (2 levels) in delegate'
from /home/sly-019/Escritorio/sinatra-blog/environments.rb:1:in `<top (required)>'
from /home/sly-019/.rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /home/sly-019/.rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `block in require'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/sly-019/.rvm/gems/ruby-2.0.0-p643/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `require'
from app.rb:5:in `<main>'
sly-019@slyDesktop:~/Escritorio/sinatra-blog$