to show how as_json can be overridden and used effectively

as_json_example.rb

# override as_json method of User class
def as_json(options={})
  super(only: [:picture, :age],
          methods: [:name])
end
# put helper methods, such as creating full name from given first_name and last_name attribute of user 
def name 
  self.first_name +" " +self.last_name
end
# example response, note that timestamps, authentication token and password digest fields are not present
# user: {
#   name: "some name",
#   picture: "url",
#   age: 20
# }
# most important: calling render json: @user returns this response