bootstrap Grid :
The Bs grid system has four classes: xs (phones), sm (tablets), md (desktops), and lg (larger desktops).
The classes can be combined to create more dynamic and flexible layouts.
.clearfix: clear floats at specific breakpoints to prevent strange wrapping with uneven content.
destroy_all( )
Delete the records of the collection directly from the database ignoring the :dependent Option.
class Person < ActiveRecord::Base
has_many :pets
end
person.pets.size # => 3
person.pets
# => [
# #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# #<Pet id: 2, name: "Spook", person_id: 1>,
# #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# ]
person.pets.destroy_all
person.pets.size # => 0
person.pets # => []
Pet.find(1) # => Couldn't find Pet with id=1