<p>我正在制作一个递归异步函数，该函数正在运行一个mysql查询。这是我正在使用的数据库：</p> <pre class="brush:php;toolbar:false;">+----+-------------------+-----------+----------+-----------+---------------------+ | id | task | completed | parentid | createdby | createdat | +----+-------------------+-----------+----------+-----------+---------------------+ | 1 | 清洁公寓 | 0 | NULL | 1 | 2022-03-24 00:47:33 | | 2 | 清洁浴室 | 0 | 1 | 1 | 2022-03-24 00:47:33 | | 3 | 清洁厨房 | 0 | 1 | 1 | 2022-03-24 00:47:33 | | 4 | 洗淋浴器 | 0 | 2 | 1 | 2022-03-24 00:47:33 | | 5 | 洗马桶 | 0 | 2 | 1 | 2022-03-24 00:47:33 | | 6 | 清洁玻璃窗格 | 1 | 4 | 1 | 2022-03-24 00:47:33 | | 7 | 清洁水龙头 | 0 | 4 | 1 | 2022-03-24 00:47:33 | | 8 | 清洁水槽 | 0 | 3 | 1 | 2022-03-24 00:47:33 | | 9 | 倒垃圾 | 1 | 3 | 1 | 2022-03-24 00:47:33 | +----+-------------------+-----------+----------+-----------+---------------------+</pre> <p>如果我将这个数据库存储在一个数组中，我可以运行这个函数：</p> <pre class="brush:php;toolbar:false;">function comp(tasks, taskId) { var task = tasks.find(task => task.id === taskId) var children = tasks.filter(t => t.parentId === taskId) task.children = children.map(child => comp(tasks, child.id)); return task }</pre> <p>来递归地将子任务嵌套到主任务中。</p> <p>问题是我对异步函数的理解不够好。</p> <p>这是我目前的进展：</p> <pre class="brush:php;toolbar:false;">async function comp(taskId) { // SELECT * FROM tasks WHERE id = taskId var task = await con.promise().query('select * from tasks where id = ' + taskId) // SELECT * FROM tasks WHERE parentId = taskId var children = await con.promise().query('select * from tasks where parentid = ' + taskId) task[0][0].children = children[0].map(child => { comp(child.id) }) console.log(task[0]) }</pre> <p>但是这返回了带有未定义子任务的任务：</p> <pre class="brush:php;toolbar:false;">[ { id: 1, task: '清洁公寓', completed: 0, parentid: null, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ undefined, undefined ] } ]</pre> <p>简而言之，我希望得到的结果如下：</p> <pre class="brush:php;toolbar:false;">{ id: 1, task: '清洁公寓', completed: 0, parentid: null, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ { id: 2, task: '清洁浴室', completed: 0, parentid: 1, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ { id: 4, task: '洗淋浴器', completed: 0, parentid: 2, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ ... ] }, { id: 5, task: '洗马桶', completed: 0, parentid: 2, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ ... ] }, ] }, { id: 3, task: '清洁厨房', completed: 0, parentid: 1, createdby: 1, createdat: 2022-03-23T23:47:33.000Z, children: [ ... ] }, }</pre> <p>有什么建议吗？</p>

await comp(child.id);

Promise.all(array)

const data = [
  {
    id: 1,
    task: "清洁公寓",
    completed: 0,
    parentid: null,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 2,
    task: "清洁浴室",
    completed: 0,
    parentid: 1,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 3,
    task: "清洁厨房",
    completed: 0,
    parentid: 1,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 4,
    task: "洗淋浴器",
    completed: 0,
    parentid: 2,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 5,
    task: "清洗马桶",
    completed: 0,
    parentid: 2,
    createdby: 1,
    createDate: "2022-03-24 00:47:33",
  },
  {
    id: 6,
    task: "清洁玻璃窗",
    completed: 1,
    parentid: 4,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 7,
    task: "清洁水龙头",
    completed: 0,
    parentid: 4,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 8,
    task: "清洁水槽",
    completed: 0,
    parentid: 3,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
  {
    id: 9,
    task: "倒垃圾",
    completed: 1,
    parentid: 3,
    createdby: 1,
    createdat: "2022-03-24 00:47:33",
  },
];

async function comp(tasks, taskId) {
  // 在这里执行你的数据库调用（这里只是模拟延迟，但函数是异步的，所以结果将保持不变）
  var task = await queryFind(tasks, taskId);
  var children = await queryFilter(tasks, taskId);

  // map()返回一个Promise数组，因为comp()返回一个Promise
  // Promise.all()返回一个Promise，当数组中的所有Promise都解决时返回
  task.children = await Promise.all(
    children.map((child) => comp(tasks, child.id))
  );

  return task;
}

// 这个函数模拟了一个异步的数据库访问。
async function queryFind(tasks, taskId) {
  // 等待100毫秒（模拟延迟）
  await sleep(100);
  return tasks.find((task) => task.id === taskId);
}

// 这个函数模拟了一个异步的数据库访问。
async function queryFilter(tasks, taskId) {
  // 等待100毫秒（模拟延迟）
  await sleep(100);
  return tasks.filter((t) => t.parentid === taskId);
}

// 延迟执行，这里应该模拟网络延迟
async function sleep(ms) {
  return new Promise((resolve) => setTimeout(() => resolve(), ms));
}

// 从ID为1的任务开始；需要将函数调用包装在一个异步方法中才能使用await
(async () => {
  const test = await comp(data, 1);
  console.log(JSON.stringify(test, null, 4));
})();