activerecord - Ruby, use of '?' - db or model method? -

activerecord - Ruby, use of '?' - db or model method? -

i love using ? boolean fields, e.g, 'animals' table "alive?" obvious. define this? name db field when creating table migration(don't think so). or automatic boolean fields or have little method in active record model class animals says def alive? if live true else false end ?

rails automatically generates method ending in ? each of fields in model. examples:

animal #=> animal(id: integer, alive: boolean, name: string) = animal.new a.alive #=> nil a.alive? #=> false a.alive = true a.alive? #=> true a.name #=> nil a.name? #=> false a.name = "giraffe" a.name? #=> true

also note can define own ? methods:

class animal def young? created_at > 1.day.ago end end

ruby-on-rails activerecord