ActiveRecord modify parameters on initialization

Question

I'm pretty sure what I'm looking for is proper usage of virtual attributes?

Regardless.

Here is an overview of my ActiveRecord in-so-far:

class User < ActiveRecord::Base
  validates :email, uniqueness: { case_sensitive: false }, email: true
  validates :username, uniqueness: { case_sensitive: false }
  validates :password, confirmation: true
  validates :password_confirmation, presence: true
end

And the schema associated:

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |u|
      u.string :email
      u.string :username
      u.string :password_hash
      u.string :salt
      u.timestamps
    end
  end
end

My goal is to be able to initialize a new record with (something like) the following:

User.new({"email"=>"emailaddresshere",
          "username"=>"usernamehere",
          "password"=>"[FILTERED]",
          "password_confirmation"=>"[FILTERED]"})

I need a way to, after all the lovely validation checks, but before attempting to create a new DB record, transform the password into the password_hash, as well as generate a salt. I know HOW to acquire the hash and salt, I just don't know how I would be able to interject a snippet of code into the record creation process, to modify the parameters provided. I am also unsure of how to make sure that it all works without throwing an UnknownAttributeError.

Any way to do this? I could obviously write a "def register" method which manually transforms everything into a new record, but then it would render the password and password_confirmation validations useless, as the record will have been transformed by the time it hits User.new().

I think my question also stems from a severe lack of overall understanding of the ActiveRecord processes... and somewhat of ruby in general — Serge
– Serge, Commented Nov 6, 2014 at 5:07

Srikanth Venugopalan · Accepted Answer · 2014-11-06 05:16:04Z

1

Use Activerecord Callbacks.

In your case you could use after_validation or before_save callback.

An example would be:

class User < ActiveRecord::Base
  validates :email, uniqueness: { case_sensitive: false }, email: true
  validates :username, uniqueness: { case_sensitive: false }
  validates :password, confirmation: true
  validates :password_confirmation, presence: true

  before_save :salt_new_password, :if=>:self.password_changed?

  private
  def salt_new_password
    # self.password = <whatever logic you use>
  end
end

answered Nov 6, 2014 at 5:16

Srikanth Venugopalan

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3 Comments

Serge Over a year ago

This seems to work. I'm going to rename the password_hash field to just password, but until I do that, I'm getting an unknown attribute error on password. I know it's a bit off-topic of the original question, but is there a way to explicitly just say not to store it in the DB?

Serge Over a year ago

Also, thank you for the reference material, that certainly clears things up for me a bit!

Serge Over a year ago

Ah, found it. attr_accessor is apparently what I was looking for. I had seen it earlier but the reference that described it did a poor job. New source: code.tutsplus.com/tutorials/…

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