The example is close but not exactly what I want to do. Instead of MySQL I like to use SQLite3 as a development database. The database is stored in a single file and there is no server that you have to configure and maintain. This allows me to delete, copy, or rename the database and proves useful for having a particular snapshot for testing.
I also want to avoid keeping a separate script or firing up a SQL Client to create a new database. ActiveRecord::Migration provides the methods needed to manage your schema. Using the example from the DevDaily site, I added a new Migration class and changed the database adapter to sqlite3. You'll also notice that you don't need a :username parameter and that the :database parameter points to a file.
require "rubygems"
require "activerecord"
ActiveRecord::Base.establish_connection(
:adapter => "sqlite3",
:host => "localhost",
:database => "/home/chuck/.ar.db")
class AddEmployee < ActiveRecord::Migration
def self.up
create_table :employees do |t|
t.column :first_name, :string
t.column :last_name, :string
end
end
def self.down
drop_table :employees
end
end
class Employee < ActiveRecord::Base
end
AddEmployee.up unless Employee.table_exists?
employee = Employee.new
employee.first_name = "Fred"
employee.last_name = "Flinstone"
employee.save
arr = Employee.find(:all)
puts arr.inspect
The new AddEmployee class inherits from Migration and creates the table when AddEmployee.up is called. I don't want to call AddEmployee.up each time since an SQLException is thrown if the table already exists. The ActiveRecord::Base#table_exists? method allows you to check this.
Running the script the first time shows that the table is created:
chuck$ ruby lib/ar.rb
== AddEmployee: migrating ====================================================
-- create_table(:employees)
-> 0.0117s
== AddEmployee: migrated (0.0196s) ===========================================
[#<Employee id: 1, first_name: "Fred", last_name: "Flinstone">]
Running the script a second time shows that a duplicate record is created in the existing table.
chuck$ ruby lib/ar.rb
[#<Employee id: 1, first_name: "Fred", last_name: "Flinstone">, #<Employee id: 2, first_name: "Fred", last_name: "Flinstone">]
Now everything I need to do with the database can be accomplished using Ruby.
