aggregate syntax

db.post.aggregate([
      {
        $lookup:
          {
            from: "like",
            localField: "post_id",
            foreignField: "post_id",
            as: "post_like_collection"
          }
      },
      {

          $lookup:
          {
            from: "comment",
            localField: "post_id",
            foreignField: "post_id",
            as: "post_comment_collection"
          }
      }

  ])