Notes posted by sselvamani22

association our data

we can load our data whenever we want.

ActiveRecord::Associations::Preloader.new.preload(@users, :company)

Preload our own with out incude

we can preload our data whenever we want.

ActiveRecord::Associations::Preloader.new.preload(@users, :address)

group on hash

‘

def group_by_hash hash, value
  hash.group_by do |k,v| 
    v > value ? "Big" : "Small"
  end
end

marks = {"Chair" => 30, "Table" => 40, "Bed" => 60, "stool" => 20}
group_by_hash(marks, 30)

Add method to instacne eval

We can add method to instance by using instance_eval.

Code example

string = "String"
string.instance_eval do
  def new_method
    self.reverse
  end
end

Output

irb(main):033:0> string.new_method
=> "gnirtS"