Reputation: 2746
In my rails projects I have a lot of association tables. And I have some validations. Nothing really difficult, and it works almost every times.
But from time to time (like tonight), I have to switch from
validates_presence_of :project_id
validates_presence_of :tag_id
validates_uniqueness_of :project_id, :scope => [:tag_id]
to
validates_presence_of :project
validates_presence_of :tag
validates_uniqueness_of :project, :scope => [:tag]
Do you know the difference ? Do you if one is better than the other ?
Upvotes: 0
Views: 155
Reputation: 13952
From the Rails Guides: http://guides.rubyonrails.org/active_record_validations.html#presence
2.9 presence This helper validates that the specified attributes are not empty. It uses the blank? method to check if the value is either nil or a blank string, that is, a string that is either empty or consists of whitespace.
class Person < ActiveRecord::Base
validates :name, :login, :email, presence: true
end
If you want to be sure that an association is present, you'll need to test whether the associated object itself is present, and not the foreign key used to map the association.
class LineItem < ActiveRecord::Base
belongs_to :order
validates :order, presence: true
end
So, you should use the second example you gave, which tests if the associated object itself is present, and not the first example, which only tests if the foreign key used to map the association is present.
Upvotes: 2