generates migration to change columns from integer to bigint

migrate_from_int_to_bigint.rb

connection ||= ActiveRecord::Base.connection
tables = connection.tables
pks_to_be_changed = ''
fks_to_be_changed = ''

tables.each do |table|
  connection.columns(table)
  pk = connection.primary_key(table)
  create_bigint_pk = false
  connection.columns(table).each do |column|
    if column.name == pk && column.type == :integer && column.limit == 4
      pks_to_be_changed << "change_column :#{table}, :#{pk}, :bigint\n"
    end

    if column.name.ends_with?('_id') && column.type == :integer && column.limit == 4 
      fks_to_be_changed << "change_column :#{table}, :#{column.name}, :bigint\n"
    end
  end
end