I am mac user (OS X Sierra 10.12.5) and I tried to set up database, but got this error
galeria egorsorokin$ rake db:migrate
rake aborted!
ActiveRecord::NoDatabaseError: FATAL: database "dev" does not exist
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:661:in 'rescue in connect'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in 'connect'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in 'initialize'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in 'new'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in 'postgresql_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in 'new_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in 'checkout_new_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in 'acquire_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in 'block in checkout'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in 'checkout'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in 'block in connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in 'connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in 'retrieve_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_handling.rb:113:in 'retrieve_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_handling.rb:87:in connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/migration.rb:916:in 'initialize'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/migration.rb:823:in 'new'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/migration.rb:823:in 'up'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/migration.rb:801:in 'migrate'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/tasks/database_tasks.rb:137:in 'migrate'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/railties/databases.rake:44:in 'block (2 levels) in <top (required)>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)
After that I tried to create database "dev" by the command "rake db:create" or "rake db:create:all" and got this error
rake db:create
rake aborted!
ActiveRecord::AdapterNotSpecified: 'development' database is not configured. Available: []
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:248:in 'resolve_symbol_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:211:in 'resolve_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:139:in 'resolve'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:169:in 'spec'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/connection_handling.rb:50:in 'establish_connection'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/tasks/database_tasks.rb:109:in 'create_current'
/Library/Ruby/Gems/2.0.0/gems/activerecord-4.2.6/lib/active_record/railties/databases.rake:17:in 'block (2 levels) in <top (required)>'
Tasks: TOP => db:create
(See full trace by running task with --trace)
I spent some hours to resolve this problem but didn't find a right solution on stackoverflow and github. Usually people who faced it recommend to check "database.yml", but looks like it's OK. Any ideas how to resolve it? Without it I can't continue the course