Using question mark character in Rails/ActiveRecord column name

问题

In keeping with Ruby's idiom of using a question mark in boolean methods (e.g. person.is_smart?), I'd like to do the same for an ActiveRecord field in Rails:

rails generate model Person is_smart?:boolean

I haven't actually run the above statement. I assume that database fields can't have a question mark in them. Will rails deal with this appropriately? Is the best practice to simply leave question marks off of models?

Using Rails 3.2.8

回答1:

Rails will automatically generate the method smart? if there is a field named 'smart'.

回答2:

One "gotcha" to be aware of if you happen to use :enum in your model, since this stores the value as an integer. The question mark attr method provided by active record expects to evaluate 0 or 1 as false / true respectively in the database. For example:

class Person
  enum mood: ['happy', 'sad', 'bored']
end

p = Person.new(mood: 'happy') # this would store mood as 0 in db
p.mood? #=> false

p.mood = 'sad' # saves as 1 in db
p.mood? #=> true

p.mood = 'bored' # saves as 2 in db
p.mood? #=> true

to see how this method works, see rails source

回答3:

Actually, Im using Rails 4 and I can't call my boolean column without the question mark

pry(main)> User.where(is_validated: false).first.is_validated
  User Load (0.9ms)  SELECT "users".* FROM "users" WHERE "users"."is_validated" = 'f' ORDER BY "users"."id" ASC LIMIT 1
=> nil
[13] pry(main)> User.where(is_validated: false).first.is_validated?
  User Load (0.8ms)  SELECT "users".* FROM "users" WHERE "users"."is_validated" = 'f' ORDER BY "users"."id" ASC LIMIT 1
=> false

来源：https://stackoverflow.com/questions/12559142/using-question-mark-character-in-rails-activerecord-column-name