`adapter_class': undefined method `to_sym' for nil:NilClass

[anthony-bernardo]

I cannot setup rom-rails

When I do a "bin/rails", I got :

/var/lib/gems/2.4.0/gems/sequel-5.6.0/lib/sequel/database/connecting.rb:17:in adapter_class': undefined method to_sym' for nil:NilClass (NoMethodError)

# config/initializers/rom.rb
ROM::Rails::Railtie.configure do |config|
  config.gateways[:default] = [:sql, 'localhost'] 
end

gem 'rom'
gem 'rom-sql'
gem 'rom-rails'

[anthony-bernardo]

Resolved by adding :

# Database for rom
gem 'pg'
gem 'sequel_pg', :require => 'sequel'

But the documentation on the Rails setup must be improved.