I am using rails 6.1.4 and added transalations table to post via this migration

class TransalatePosts < ActiveRecord::Migration[6.1]
  def change
    def self.up
      Post.create_translation_table!({
        :title => :string,
        :body => :text
      }, {
        :migrate_data => true,
        :remove_source_columns => true
      })
    end
  
    def self.down
      Post.drop_translation_table! :migrate_data => true
    end
  end
end

My post model looks like this

class Post < ApplicationRecord
    translates :title,:body

    validates :title, presence:true
    validates :body, presence:true
end

What is exactly happening wrong ? I am exactly following the steps any help will be appreciated