filters.rb

class CoolController < ApplicationController
  before_action :setup_conditions, only: [ :index ]
  before_action :filter_gender, only: [ :index ]
  before_action :filter_birthday, only: [ :index ]

  def index
    @people = Person.where(@conditions)
  end
  
  
  private
  
  def setup_conditions
    @conditions = {}
  end
  
  def filter_gender
    return if !params[:gender]
    @conditions[:gender] = params[:gender]
  end
  
  def filter_birthday
    return if !params[:start_date] && !params[:end_date]
    @conditions[:birthday] = (params.fetch(:start_date, Time.now)..params.fetch(:end_date, Time.now))
  end
end