Question

I am creating users from emails.
If an email exists I want to skip creating that user.

Here is my model method:

def invite_users(emails, board)
      invalid_emails =[]
      emails.each do |email| 
        user = User.new(:email => email)
          user.save ? Participant.make(user, board) : invalid_emails << email unless user.errors.each {|key, msg| msg == "has already been taken"}
      end
       invalid_emails if invalid_emails.any?
  end

I want to check if the error generated from user.save is a duplicate email error. If so I don’t want to put that email in the invalid_emails array.

How can I do this?

Answer 1

validates_uniqueness_of is useless for such purposes.

The canonical thing to do is to add a unique index on email to the users table, and use code like:

begin
  -- do stuff that creates records --
rescue ActiveRecord::StatementInvalid => e
  raise unless /Mysql::Error: Duplicate entry/.match(e)  
end

if you want to emulate create or find, you do something like

 result = nil
 begin
   result = User.create(:email => xxxx)
 rescue ActiveRecord::StatementInvalid => e
   if /Mysql::Error: Duplicate entry/.match(e)
     user = User.find_by_email(xxx)
   else
     raise
   end
 end