Converting Drupal tables to RoR from any to any database.

OK, OK, it's fairly not only for Drupal source databases :-)

STEP 1 - init databases connections
Create two new connections in database.yml file like this:

# DATABASE CONVERTING SPECIFIC
# old connection
old:
  adapter: mysql
  database: dbname
  username: username
  password: userpass
  host: localhost

# new connection (may be like your development or production connection)
new:
  adapter: postgresql
  database: dbname
  username: username
  password: userpass
  schema_order: development # for example
  host: localhost

STEP 2 - write rake task
create convert.rake file in your lib/tasks rails application directory

    1 namespace :db do
    2   namespace :convert do
    3     task :old2new => :environment do
    4       print "OK, let's do it now!\n"; STDOUT.flush
    5 
    6       # define universal model for old tables
    7       class OldModel < ActiveRecord::Base
    8       end
    9 
   10       # demonic convertor
   11       def convert(srctable, dstclass)
   12         print "- converting class " + dstclass.to_s + "...\n"; STDOUT.flush
   13 
   14         dstclass.establish_connection(:new)
   15         dstclass.delete_all
   16 
   17         OldModel.set_table_name(srctable)
   18         OldModel.find(:all).each { |old|
   19           new = dstclass.new
   20           new = yield(old, new)
   21           new.save(false)
   22         }
   23       end
   24 
   25       # connect to old dying database
   26       ActiveRecord::Base.establish_connection(:old)
   27 
   28       # CONVERTING
   29 
   30       # users
   31       convert('rctc_users', User) {|old, new|
   32         # prepare each field individually, yeah.
   33         new.id = old.uid
   34         new.login = old.name
   35         new.email = old.mail
   36         new.password = Digest::MD5.hexdigest(old.pass + SALT)
   37         new
   38       }
   39 
   40       # convert your tables below like above
   41       # ...
   42 
   43       print "Wow! Processing complete!\n"
   44     end
   45   end
   46 end

STEP 3 - RUN IT!

$ rake db:convert:old2new