Question

我正在对Sequelize进行查询，然后想要根据db中的每个用户运行查询。我不知道如何将这个forEach循环转换为Promise，所以我可以在forEach循环结束后执行操作....

users.forEach(user => {
  let userHideCount = 0
  Comment_List.findAll({
    where: {user_id:user}, attributes: ['user_id','cid'], include: [
      {model: Comment, attributes: ['verb','created_time']}
    ],
    order: [[ Comment, 'created_time', 'DESC' ]],
  })
  .then(cl => {
    cl.forEach(comment => comment.get({plain:true}).comments[0].verb === 'hide' ? userHideCount++ : null)
    hiddenCounts[user] = userHideCount
  })
})

或许有更好的方法可以解决这个问题......任何帮助都非常适合！

Answer 1

使用Promise.all并将forEach转换为返回承诺的map。例如：

var userPromises = users.map(user => {
  let userHideCount = 0
  return Comment_List.findAll({
    where: {user_id:user}, attributes: ['user_id','cid'], include: [
      {model: Comment, attributes: ['verb','created_time']}
    ],
    order: [[ Comment, 'created_time', 'DESC' ]],
  })
  .then(cl => {
    cl.forEach(comment => comment.get({plain:true}).comments[0].verb === 'hide' ? userHideCount++ : null)
    hiddenCounts[user] = userHideCount
  })
})

// Then, sometime later:
Promise.all(userPromises).then(() => {
    // Do stuff.
})

循环异步操作

1 个答案: