compact过滤数组中的nil

http://ruby-doc.org/core-2.2.0/Array.html#method-i-compact

compact → new_aryclick to toggle source

Returns a copy of self with all nil elements removed.

[ "a", nil, "b", nil, "c", nil ].compact
                  #=> [ "a", "b", "c" ]

 render :json => {
      :videos => result_videos.compact.map do |video|
        if video.class == CmsTvIVideo
          if video.video_type == "live"
            {
              :title => video.title,
              :live_name => video.live_name,
              :live_id=> video.live_id,
              :big_horizontal_image => video.res_img_l,
              :middle_horizontal_image => video.res_img_m,
              :big_vertical_image => video.res_img_s,
              :middle_vertical_image => video.middle_vertical_image,
              :mtype => "live"
            }