Using validate_uniqueness in Rails 4

Question

I have added another login filled in devise, i.e. contact_no. Either email address or contact no. should provided. To make contact_no unique I added a check in my user model for uniquness.

validates_uniqueness_of :contact_no, allow_nil: true, allow_blank: true

But, it keeps throwing error

Mysql2::Error: Duplicate entry '' for key 'index_users_on_contact_no':

Try removing `allow_nil: true` – Pavan Jul 02 '17 at 18:39 — Pavan, Jul 02 '17 at 18:39

score 1 · Accepted Answer · answered Jul 02 '17 at 18:46

1

This is because of allow_blank: true

Refer to this answer

MySql unique index allows multiple NULL values(if column is NULLable), however in your case, you have allow_blank set to true, which results in multiple empty strings "" inserted to table, which is causing that error

You can fix this by removing allow_blank: true and manually setting contact_no to nil when its blank

For ex:

# user.rb  
after_initialize :set_default, unless: persisted?

def set_default
   self.contact_no = nil if contact_no.nil? || contact_no.blank?
end

answered Jul 02 '17 at 18:46

Sujan Adiga

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Yes! I was bit confused with `allow_nil` – Pavan Jul 02 '17 at 18:51
Okay. I will try that and get back to you. – Shilpi Agrawal Jul 03 '17 at 03:30

Using validate_uniqueness in Rails 4

1 Answers1