Why is validation being skipped? - ruby

Question

I have an email ActiveRecord (sub-class, different PG DB) with the following validation:
class Email < DbRecord
belongs_to :user
attr_accessor :skip_validation
alias_method :skip_validation?, :skip_validation
validates :value,
presence: true,
uniqueness: true,
format: {
with: URI::MailTo::EMAIL_REGEXP,
message: "is an invalid email address",
allow_blank: true,
},
unless: :skip_validation?
before_validation { |record| record.value = record.value&.downcase }
skip_validation is nil. There are no other instance methods.
When there's no user_id the validation works as expected.
> e = Email.new(value: "foo#bar")
=> #<Email id: nil, user_id: nil, value: "foo#bar">
> e.valid?
=> false
When there's a user_id the bogus email doesn't trigger the validation.
> e = Email.new(user_id: 7, value: "foo#bar")
=> #<Email id: nil, user_id: 7, value: "foo#bar">
> e.valid?
=> true
Note that setting validate: true on belongs_to doesn't help:
class Email < DbRecord
belongs_to :user, validate: true
Still presents:
> e = Email.new(user_id: 7, value: "foo#bar")
=> #<Email id: nil, user_id: 7, value: "foo#bar">
> e.valid?
=> true
Why is that? What else should I be looking at/for?

Answer 1

Two-step answer:
"foo#bar" is a valid email according to URI::MailTo::EMAIL_REGEXP...
I can't even, but others have hit the same issue so...
As I always tell everyone else: check your assumptions. I assumed the validation was failing because of the email address, and in my sleep-deprived state I didn't verify the errors.
So why was it failing validation?
Rails 5 changed belongs_to to make the related ID mandatory, so in order for this to make sense (in my use-case) I also needed to add:
belongs_to :user, optional: true
to get the expected error messages back during validation.