```ruby
class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  has_many :pathway_donors
  has_many :pathways

  validates :email, :first_name, :last_name, presence: true
end
```

Add private method and after_create
user
```ruby
class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  has_many :pathway_donors
  has_many :pathways

  validates :email, :first_name, :last_name, presence: true
  after_create :update_access_token!  

  private
  def update_access_token!
    self.access_token = "#{self.id}:#{Devise.friendly_token}"
    save
  end

end
```
assistant