= link_to new_admin_attendance_path(event_id: event.id, date: params[:date]),
remote: true, class: 'btn btn-success' do %span.glyphicon.glyphicon-plus

def new
    @attendance = Attendance.new

    if params[:event_id]
      @attendance.event_id = params[:event_id]
    end

    respond_to do |format|
      format.js
    end
  end