```ruby
class User < ActiveRecord::Base
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :name, presence: true, length: { maximum: 50 }
  validates :email, presence: true, length: { maximum: 255 },
    format: { with: VALID_EMAIL_REGEX },
    uniqueness: true
end
```

Set email uniqueness as case insensitive
user
```ruby
class User < ActiveRecord::Base
  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  validates :name, presence: true, length: { maximum: 50 }
  validates :email, presence: true, length: { maximum: 255 },
    format: { with: VALID_EMAIL_REGEX },
    uniqueness: { case_sensitive: false }
end
```
assistant