```ruby
require 'rails/generators'
require 'rails/generators/migration'

module Markable
  class MigrationGenerator < Rails::Generators::Base
    include Rails::Generators::Migration

    desc "Generates migration for Mark model"

    def self.orm
      Rails::Generators.options[:rails][:orm]
    end

    def self.source_root
      File.join(File.dirname(__FILE__), 'templates', (orm.to_s unless orm.class.eql?(String)) )
    end

    def self.orm_has_migration?
      [:active_record].include? orm
    end

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

    def create_migration_file
      if self.class.orm_has_migration?
        migration_template 'migration.rb', 'db/migrate/markable_migration'
      end
    end
  end
end

```

Add .rb extension to generated migration file
user
```ruby
require 'rails/generators'
require 'rails/generators/migration'

module Markable
  class MigrationGenerator < Rails::Generators::Base
    include Rails::Generators::Migration

    desc "Generates migration for Mark model"

    def self.orm
      Rails::Generators.options[:rails][:orm]
    end

    def self.source_root
      File.join(File.dirname(__FILE__), 'templates', (orm.to_s unless orm.class.eql?(String)) )
    end

    def self.orm_has_migration?
      [:active_record].include? orm
    end

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

    def create_migration_file
      if self.class.orm_has_migration?
        migration_template 'migration.rb', 'db/migrate/markable_migration.rb'
      end
    end
  end
end

```
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