Question

我有两个User属于Status关系的模型。我正在尝试跟踪对status记录中的User列所做的更改。在我的钩中，我有：

afterUpdate: (instance, options) => {
  if (instance.dataValues.statusId !== instance._previousDataValues.statusId){
    const Track = {
      new_status: sequelize.models.Status.findById(instance.dataValues.statusId).then(status => {
        console.log('1._____');
        console.log(status.dataValues.name);
        return status.dataValues.name;
      })
    }
    console.log('2.____');
    console.log(Track.new_status);
  } else{
    console.log('Status is not changed');
  }
}

输出：

2.____
Promise {
  _bitField: 0,
  _fulfillmentHandler0: undefined,
  _rejectionHandler0: undefined,
  _promise0: undefined,
  _receiver0: undefined }
Executing (default): SELECT "id", "name", "detail", "createdAt", "updatedAt" FROM "Statuses" AS "Status" WHERE "Status"."id" = 18;
1._____
Cancelled

我看到在console.log(Track.new_status)处查询尚未完成，并且在console.log(status.dataValues.name)处正确返回了状态名称。我该如何等待它完成查询？

Answer 1

使用async/await：

async function getTrack(trackID) {
  const track = await Track.findByPk(trackID);
  console.log('track', track);
}

使用承诺：

function getTrack(trackID) {
  const track = Track.findByPk(trackID)
  .then((track) => {
    console.log('track', track);
  });
}

顺序查询返回Promise。如何等待查询返回结果？

1 个答案: