ruby on rails - Insert data in migration if it does not exist -

i have following migration:

sequel.migration       create_table :user_settings       primary_key :id        string :signature, null: true, text: true     end      alter_table :user_settings       add_foreign_key :user_id, :users, null: false, on_delete: :cascade        add_index :user_id     end   end    down     drop_table :user_settings   end end 

this add default user settings.

the problem have want create row in user_settings table every user in database not have row, prior migration.

i want check if each user has row a matching user_id in database , if not, want insert default values.

how can in migration?

normally, kind of things done using rake task need in migration. guess have added association in user , usersetting model , has_one association. need create new migration file

def   users = user.includes([:user_setting]).where(:user_setting => {:user_id => nil})   users.each |user|     user.create_user_setting     # or can write     # usersetting.create({:user_id => user.id, :signature => 'your-custom-text'})   end end