等待在嵌套的 for...of 循环中不起作用 - typeorm - nodejs

Question

我正在尝试获取一些数据并将其添加到现有数据集（对象），但数据显示为空。但是，我可以使用 typeorm 查询从数据库中获取数据。

我意识到我的错误是该方法在我的循环完全迭代之前返回数据。发现for...of 循环更适合async/await。但仍然没有运气。

这是我想要做的：

export const getTopicDetails = async (
  req: Request,
  res: Response
): Promise<Response> => {
  try {
    let topicDetail: any = await Chapter.createQueryBuilder("topic")
      .leftJoinAndSelect("topic.grs", "grs")
      .leftJoinAndSelect("grs.srs", "srs")
      .leftJoinAndSelect("grs.points", "grs_points")
      .leftJoinAndSelect("srs.points", "srs_points")
      .leftJoinAndSelect("grs_points.srs", "grs_points_srs")
      .leftJoinAndSelect("grs_points.points", "grs_points_points")
      .leftJoinAndSelect("srs_points.points", "srs_points_points")
      .where("topic.id = :id", { id: req.params.id })
      .andWhere("grs.sequence IS NULL")
      .andWhere("srs.parent_sr_id IS NULL")
      .orderBy("grs.id", "ASC")
      .addOrderBy("grs_points.sequence", "ASC")
      .getOne();

    for (const gr of topicDetail.grs) {
      for (const point of gr.points) {
        for (const firstLevelPoint of point.points) {
          var srs = await Srmodule.createQueryBuilder("srs")
            .where("srs.grId = :grId", { grId: firstLevelPoint.id })
            .getMany();

          // this is returning an empty object
          nestedProperty.set(topicDetail, `2`, srs);
          
          // this thing returns as expected
          nestedProperty.set(topicDetail, `3`, [
            {
                "id": 5,
                "srNo": "1.01.02.01",
                "grId": 7,
                "title": "test",
                "description": "lorem ipsum dolor sit amet",
                "created_at": "2021-06-21",
                "addedBy": 1,
            }
        ]);
        }
      }
    }

    if (topicDetail) {
      return res.status(200).json({
        status: true,
        data: topicDetail,
      });
    } else {
      return res.status(404).json({ status: false, error: "No data found" });
    }
  } catch (error) {
    return res.status(500).json({ status: false, error: error });
  }
};

这是我得到的回应：

"status": true,
    "data": {
        "1": 1,
        "2": {},
        "3": [
            {
                "id": 5,
                "srNo": "1.01.02.01",
                "grId": 7,
                "title": "test",
                "description": "lorem ipsum dolor sit amet",
                "created_at": "2021-06-21",
                "addedBy": 1,
            }
        ]
    }

感谢任何帮助。

Answer 1

“await”只能在异步函数中使用！

async function getData() {
  const data = await doSomeAsyncWork();
  console.log(data)
}

function doSomeAsyncWork() {
  return Promise.resolve("data");
}

getData();

所以将你所有的 for 循环包装在一个异步函数中！