cities_datatable.rb

class CitiesDatatable
  delegate :image_tag,:edit_city_path,:params, :h, :link_to, :number_to_currency, to: :@view

  def initialize(view)
    @view = view
  end

  def as_json(options = {})
    {
      sEcho: params[:sEcho].to_i,
      iTotalRecords: City.count,
      iTotalDisplayRecords: cities.total_entries,
      aaData: data
    }
  end

private

  def data
    cities.map do |city|
      [ "<div class='main-name'>" + 
        link_to(city.name,city,{:remote => :true}) + 
        "</div>",
        (city.country.name if !city.country.nil?),
        (city.desc if !city.desc.nil?),
        "<div class = 'tools dn'> <ul>" + 
        ["<li>" + 
        link_to(image_tag("/assets/icons/view.png"),city,{:remote =>:true}) + 
        "</li>", "<li>" + 
        link_to(image_tag("/assets/icons/edit.png"), edit_city_path(city) ,{:remote =>:true}) + 
        "</li>", "<li>" + 
        link_to(image_tag("/assets/icons/delete.png"),city,method: :delete, data: { confirm: 'Are you sure?' }) + 
        "</li>"].join("  ") + 
        "</ul> </div>"
      ]
    end
  end

  def cities
    @cities ||= fetch_cities
  end

  def fetch_cities
    cities = City.order("#{sort_column} #{sort_direction}")
    cities = cities.page(page).per_page(per_page)
    if params[:sSearch].present?
      cities = cities.where("name like :search", search: "%#{params[:sSearch]}%")
    end
    cities
  end

  def page
    params[:iDisplayStart].to_i/per_page + 1
  end

  def per_page
    params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
  end

  def sort_column
    columns = %w[name ]
    columns[params[:iSortCol_1].to_i]
  end

  def sort_direction
    params[:sSortDir_0] == "desc" ? "desc" : "asc"
  end
end