How to compare Rails enum types - ruby-on-rails

Question

I have the following enum model in my Rails (4) application:
class Dual < ActiveRecord::Base
enum dual: [:dual, :not_dual]
validates :dual, uniqueness: true
validates :dual, presence: true
end
And I have another model which has many Duals:
class SillColour < ActiveRecord::Base
has_many :sill_colour_duals, dependent: :destroy
has_many :duals, through: :sill_colour_duals
end
I want to be able to test if an instance of SillColour has a Dual enum. This is all I could get to work:
dual = Dual.find(1)
not_dual = Dual.find(2)
sill_colour.duals.include?(dual)
sill_colour.duals.include?(not_dual)
Obviously this is extremely unreliable as the ID of the Duals could be anything in production (for testing IDs are fixed). I tried this:
dual = Dual.where(dual: 0)
not_dual = Dual.where(dual: 1)
and even given the database duals table looks like this:
id | dual
----+------
1 | 0
2 | 1
My tests fail and it seems to be because dual and non_dual are no longer comparing correctly. I've examined them using pry and they appear to be the same as before, but clearly they're not.
Surely there must be a better way? I envisaged being able to do this:
sill_colour.duals.include?(Dual.dual)
sill_colour.duals.include?(Dual.not_dual)
but this doesn't work either.
Any suggestions?

Answer 1

I'll try to answer with a code from my app
class User < ActiveRecord::Base
has_many :contacts
end
class Contact < ActiveRecord::Base
enum status: [:dual, :not_dual]
# see scopes
scope :dual, -> {where(status: Contact.statuses['dual']) }
scope :not_dual, -> {where(status: Contact.statuses['not_dual']) }
end
Now console, check if a User instance has a contact with dual status:
2.1.5 :001 > u = User.last
User Load (0.8ms) SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT 1
=> #<User id: 1, email: "...", ...>
2.1.5 :003 > u.contacts.dual
Contact Load (0.3ms) SELECT "contacts".* FROM "contacts" WHERE "contacts"."user_id" = $1 AND "contacts"."status" = 0 [["user_id", 1]]
=> #<ActiveRecord::AssociationRelation []>
2.1.5 :004 > u.contacts.not_dual
Contact Load (0.3ms) SELECT "contacts".* FROM "contacts" WHERE "contacts"."user_id" = $1 AND "contacts"."status" = 1 [["user_id", 1]]
=> #<ActiveRecord::AssociationRelation []>
As you can see both return empty array, so calling any? on empty array will return false both. Because I don't have any contact with status dual or not_dual, let's create one.
Find a contact:
2.1.5 :005 > c = Contact.last
Contact Load (0.5ms) SELECT "contacts".* FROM "contacts" ORDER BY "contacts"."id" DESC LIMIT 1
=> #<Contact id: 3, user_id: 1, ..., ...., status: nil>
Set it as dual:
2.1.5 :006 > c.dual!
(0.1ms) BEGIN
SQL (15.1ms) UPDATE "contacts" SET "status" = $1, "updated_at" = $2 WHERE "contacts"."id" = 3 [["status", 0], ["updated_at", "2014-12-29 13:16:45.576778"]]
(25.5ms) COMMIT
=> true
Now check if user has dual or not_dual contacts:
2.1.5 :009 > u.contacts.dual.any?
(0.2ms) SELECT COUNT(*) FROM "contacts" WHERE "contacts"."user_id" = $1 AND "contacts"."status" = 0 [["user_id", 1]]
=> true
2.1.5 :010 > u.contacts.not_dual.any?
(0.3ms) SELECT COUNT(*) FROM "contacts" WHERE "contacts"."user_id" = $1 AND "contacts"."status" = 1 [["user_id", 1]]
=> false
2.1.5 :011 >
Checking if user instance has a dual enum returns true. In your case instead of user it will be sill_colour.
If you don't like scopes you can use where:
u.contacts.where(status: Contact.statuses['dual']).any?
=> true
http://edgeapi.rubyonrails.org/classes/ActiveRecord/Enum.html
class Dual < ActiveRecord::Base
enum status: [:dual, :not_dual]
end
Having the class as the one above you can check the status like this:
dual = Dual.find(params[:id])
dual.dual? # will return true or false depends on the status you set.
dual.not_dual? # same, true or false
dual.status = "dual" # if status was set to 0 or not_dual if status was set to 1