正在获取 Firebase Firestore 引用

Question

假设我有以下 Firestore 数据结构：

tickets

{
    name: "Testticket",
    open: true,
    users: [
        "users/abcdefg1234" // Firestore reference
    ]
}

收藏users

{
    name: "John Doe",
    color: "green"
}

我的目标是获取所有open为真的门票，包括用户 object 而不是参考。

目前我正在这样做：

// Firebase Functions node.js code

async function getUserData(item) {
  const queryResult = await item.get();
  return await queryResult.data();
}

exports.getOpenTickets = async (request, response) => {
  const query = await db.collection("tickets").where("open", "==", true).get();

  let tickets = [];
  query.forEach(async (doc) => {
    let data = doc.data();
    console.log("data", data);

    data.userObjects = await Promise.all(data.users.map(getUserData));
    console.log("data.userObjects", data.userObjects);

    tickets.push(data);
  });

  return response.json(tickets);
};

问题：用户数据已获取，但主 function 并未等待（已通过控制台日志语句进行检查）。

这是我的 node.js 控制台日志：

i  functions: Beginning execution of "api"
!  Google API requested!
   - URL: "https://oauth2.googleapis.com/token"
   - Be careful, this may be a production service.
>  data {
>    open: true,
>    name: 'Testticket',
>    users: [
>      DocumentReference {
>        _firestore: [Firestore],
>        _path: [ResourcePath],
>        _converter: [Object]
>      }
>    ]
>  }
i  functions: Finished "api" in 1069.554ms
>  data.userObjects [ { color: 'green', name: 'John Doe' } ]

如何解决这个问题？

Answer 1

如果你想在一个循环中运行异步操作，那么你不应该使用forEach 。 尝试使用for of循环重构代码，如下所示：

exports.getOpenTickets = async (request, response) => {
  const snap = await db.collection("tickets").where("open", "==", true).get();
  let tickets = [];
  
  for (const doc of snap.docs ) {
    let data = doc.data();
    console.log("data", data);

    data.userObjects = await Promise.all(data.users.map(getUserData));
    console.log("data.userObjects", data.userObjects);

    tickets.push(data);
  }

  return response.json(tickets);
};

另请查看 Using async/await with a forEach loop 。