从mongodb获取嵌套模型引用

Question

• 我在下面有代码来获取用户的书签博客

  问题 - ＆gt;我还想要用户对象选择字段

  Bookmarkblog.aggregate([{
    $lookup:
       {
          from: "blogs",
          localField: "blog",
          foreignField: "_id",
          as: "blog"
      }
   }, {
    $match: { "user": mongoose.Types.ObjectId(req.headers.userid) }
   }])
  

  当前输出

  [
    {
      "_id": "5a82ce0d80f62b18bc5ac5bf",
      "blog": [
        {
          "_id": "5a696a31f78861dd29bec5bd",
          "user": "59bbbe071b4a358f43dc0cbf",
          "category": "59c3b5022ad1854d496cfb8b",
          "image": [
            "57904805-imac_pro_large.jpg"
          ],
          "tags": [
            "Mac"
          ],
          "content": "",
          "title": "iMac Pro, the most powerful Mac ever",
          "created": "2018-01-25T05:25:05.025Z",
          "__v": 0
        }
      ],
      "user": "59e5a62427543c54603050de",
      "created": "2018-02-13T11:37:49.071Z",
      "__v": 0
    }
  ]