```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

  validates :email, presence: true, uniqueness: {case_sensitive: false}

  has_many :comments, :foreign_key => 'author_id'
end
```

Add confirmable module to User model
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,
         :confirmable

  validates :email, presence: true, uniqueness: {case_sensitive: false}

  has_many :comments, :foreign_key => 'author_id'
end
```
assistant