Rails Database Mechanics

Rails DB Mechanics

• ActiveRecord
  • Layer in RoR which is the connection between the rails application and the underlying database
  • For advanced designs, there are options other than Activerecord
• Naming
  • Model.rb file is named singular, e.g. User
  • Corresponding db table is plural and lower case, e.g. users
• Correspondences
  • Each instance of the class (e.g. User) corresponds to a single record in the dabase
  • When a query returns a bunch of records, you get a collection of instances of the class
  • (this is classic Active Record model)
• Attributes
  • Rails will automagically create the methods to access each field of the record in the database
• Different database ‘servers’
  • Sqllite - local database, no need for a server
  • MySql - Standard industrial strength database, free
  • Postgress - Becoming very popular with Rails community
• Migration Rails Guide: Migrations
  • rails generate model -h
  • rails generate migration -h
• Datatypes supported by Rails
  • DB datatypes for Rails 4

• Queries and other ways to access the database

• Validations
  • Rails Validations
• Tools and notes
  • Check out MesaSQLite
  • Handy Rake Info: Rake “tasks” (commands)