Question

I’m writing a SaaS model application.
My application database consist of two logic parts:

• application tables – such as user, roles…
• user-defined tables (he can generate them from UI level) that can be different for each application instance

All tables are created by rails migrations mechanism.

I would like to put user-defined tables in another directory:

• db/migrations – application tables
• db/migrations/custom – tables generated by user

so I can do svn:ignore on db/migrations/custom, and when I do updates of my app on clients servers it would only update application tables migrations.

Is there any way to achieve this in rails?

Answer 1

@Vasily thank’s for your response. After reading it and couple more questions from stackoverflow I came up with this solution:

Since I write my own generator to create user tables I included Rails::Generators::Migration in it so I can override next_migration_number method like this:

def self.next_migration_number(dirname)
 if ActiveRecord::Base.timestamped_migrations
   Time.now.utc.strftime("custom/%Y%m%d%H%M%S")
 else
   "custom/%.3d" % (current_migration_number(dirname) + 1)
 end
end

Now all migrations generated by user are created in db/migrations/custom directory.

Then I wrote normal rails migration that executes all migrations from db/migrations/custom directory:

class ExecuteCustomMigrations < ActiveRecord::Migration
   MIGRATIONS_PATH='db/migrate/custom'
   def self.up
     Dir["#{MIGRATIONS_PATH}/[0-9]*_*.rb"].
     sort.map{|filename|require filename}.flatten.
     each{|class_name| const_get(class_name).up}
   end

   def self.down
     Dir["#{MIGRATIONS_PATH}/[0-9]*_*.rb"].sort.reverse.
     map{|filename|require filename}.flatten.
     each{|class_name| const_get(class_name).down}
   end
end

After user creates custom table i call this migration with this code:

Rake::Task["db:migrate:redo"].execute("VERSION=20110108213453")