-*- indent-tabs-mode:nil; -*-

# HoboFields - Migration Generator

Note that these doctests are good tests but not such good docs. The migration generator doesn't really fit well with the doctest concept of a single IRB session. As you'll see, there's a lot of jumping-through-hoops and doing stuff that no normal user of the migration generator would ever do.

Firstly, in order to test the migration generator outside of a full Rails stack, there's a few things we need to do. First off we need to configure ActiveSupport for auto-loading

    >> require 'rubygems'
    >> require 'activesupport'
    >> require 'activerecord'

We also need to get ActiveRecord set up with a database connection

    >> mysql_adapter = defined?(JRUBY_VERSION) ? 'jdbcmysql' : 'mysql'
    >> mysql_user = 'root'; mysql_password = ''
    >> mysql_login = "-u #{mysql_user} --password='#{mysql_password}'"
    >> mysql_database = "hobofields_doctest"
    >> system "mysqladmin #{mysql_login} --force drop #{mysql_database} 2> /dev/null"
    >> system("mysqladmin #{mysql_login} create #{mysql_database}") or raise "could not create database"
    >> ActiveRecord::Base.establish_connection(:adapter => mysql_adapter,
                                               :database => mysql_database,
                                               :host => "localhost", 
                                               :username => mysql_user, 
                                               :password => mysql_password)

Some load path manipulation you shouldn't need:

    >> $:.unshift File.join(File.expand_path(File.dirname(__FILE__)), '../../hobofields/lib')
    >> $:.unshift File.join(File.expand_path(File.dirname(__FILE__)), '../../hobosupport/lib')

And we'll require:

    >> require 'hobosupport'
    >> require 'hobofields'

OK we're ready to get going.

We'll define a method to make that easier next time

    >>
     def migrate(renames={})
       up, down = HoboFields::MigrationGenerator.run(renames)
       puts up
       ActiveRecord::Migration.class_eval(up)
       ActiveRecord::Base.send(:subclasses).each { |model| model.reset_column_information }
       [up, down]
     end

## Alternate Primary Keys

### create

   >>
    class Foo < ActiveRecord::Base
      fields do
      end
      set_primary_key "foo_id"
    end
   >> up, down = HoboFields::MigrationGenerator.run
   >> up
   =>  
     "create_table :foos, :primary_key => :foo_id do |t|
     end"
   >> migrate
  
### migrate from

   >>
    class Foo < ActiveRecord::Base
      set_primary_key "id"
    end
   >> up, down = HoboFields::MigrationGenerator.run({:foos => {:foo_id => :id}})
   >> up

   => "rename_column :foos, :foo_id, :id"
   >> migrate({:foos => {:foo_id => :id}})

### migrate to

   >>
    class Foo < ActiveRecord::Base
      set_primary_key "foo_id"
    end
   >> up, down = HoboFields::MigrationGenerator.run({:foos => {:id => :foo_id}})
   >> up

   => "rename_column :foos, :id, :foo_id"
   >> migrate({:foos => {:id => :foo_id}})

### ensure it doesn't cause further migrations

   >> up, down = HoboFields::MigrationGenerator.run
   >> up
   => ""

## Cleanup

   >> system  "mysqladmin #{mysql_login} --force drop #{mysql_database} 2> /dev/null"