Ajax Datatable

ItemDatatable.rb

class ItemsDatatable
  delegate :params, :h, to: :@view

  def initialize(view)
    @view = view
  end

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

private

  def data
    items.map do |item|
      [
        item.id,
      ]
    end
  end

  def items
    @items ||= fetch_items
  end

  def fetch_items
    items = Item.order("#{sort_column} #{sort_direction}")
    items = items.page(page).per_page(per_page)
    if params[:sSearch].present?
      items = items.where("CAST(items.id AS TEXT) ilike :search", search: "%#{params[:sSearch]}%")
    end
    items
  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[id]
    sort_col = "items.#{columns[params[:iSortCol_0].to_i]}"
  end

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