Simplifying code using Rails presence Method

Rails has a useful method called presence that allows you to use the value of an object, otherwise it returns nil.

It is very simple. Below is the implemenation.

  def presence
    self if present?
  end

We can use it to refactor the following code

state   = params[:state]   if params[:state].present?
country = params[:country] if params[:country].present?
region  = state || country || 'US'

to this

region = params[:state].presence || params[:country].presence || 'US'