Get ID of Rails Model before saving…?

Question

How do you get the id of a rails model before it is saved?

For example, if I create a new model instance, how can I get its ID before it is saved?

I know t

Answer 1

I was looking for this too, and I found an answer:

Let's suppose model name is "Model" and table name is "models"

model.rb

before_save {
    next_id=Model.connection.select_value("Select nextval('models_id_seq')")
}

This will output the value your record will take for id IF it gets saved

Answer 2

I don't believe there are any workarounds since the id is actually generated by the database itself. The id should not be available until after the object has been saved to the database.

Answer 3

Consider doing what you want right after the instance is created.

after_create do
  print self.id
end

Answer 4

I know it's an old question, but might as well throw my answer in case anyone needs to reference it

UserModel

class User < ActiveRecord::Base
before_create :set_default_value

def set_default_value
   self.value ||= "#{User.last.id+1}"
end