warrenlalata

Transactions

As your business logic gets complex you may need to implement transactions. The classic example is a bank funds transfer from account A to account B. If the withdrawal from account A fails then the deposit to account B should either never take place or be rolled back.

Basics

All the complexity is handled by ActiveRecord::Transactions. Any model class or instance has a method named .transaction. When called and passed a block, that block will be executed inside a database transaction. If there's an exception raised, the transaction will automatically be rolled back.

Example

warrenlalata

HTTP status code symbols for Rails

Thanks to Cody Fauser for this list of HTTP responce codes and their Ruby on Rails symbol mappings.

Status Code Symbol
1xx Informational
100 :continue
101 :switching_protocols
102 :processing

warrenlalata

Capistrano::Rails::Db
cap production deploy:db:abort_if_pending_migrations  # Run rake db:abort_if_pending_migrations
cap production deploy:db:create                       # Run rake db:create
cap production deploy:db:drop                         # Run rake db:drop
cap production deploy:db:migrate                      # Run rake db:migrate         Migrate the database (options: VERSION=x, VERBOSE=false, SCOPE=blog)
cap production deploy:db:migrate:down                 # Run rake db:migrate:down    Run the "down" for a given migration VERSION
cap production deploy:db:migrate:redo                 # Run rake db:migrate:redo    Rollback the database one migration and re migrate up (options: STEP=x, VERSION=x)
cap production deploy:db:migrate:reset                # Run rake db:migrate:reset   Reset your database using your migrations
cap production deploy:db:migrate:status               # Run rake db:migrate:status  Display status of migrations
cap production deploy:db:migrate:up                   # Run rake db:mi