Question

onSnapshot方法出现问题。它不会等待第二次onsnapshot调用，因此返回的值不正确。在第二次onsnapshot调用中获取的用户，当值已经返回时，稍后将在控制台日志中显示。

如果您喜欢其他结构，欢迎提出任何解决方案和建议！谢谢大家。

export const FirebaseGetStrikeLists2 = async (houseId: string) => {
    let strikes: StrikeListDocument[] = [];

    firestore()
        .collection(FirebaseConstraints.HouseCollection)
        .doc(houseId)
        .collection(FirebaseConstraints.StrikeSubCollection)
        .onSnapshot(async x => {
            x.forEach(async x => {
                const strikeListDocument = x.data() as StrikeListDocument
                strikeListDocument.users = []
                strikeListDocument.id = x.id;

                x.ref.collection(FirebaseConstraints.UserCollection).onSnapshot(
                    async x => {
                        let strikeListUsers: StrikeListDocumentUser[] = [];
                        x.forEach(async y => {
                            let userDocument = y.data() as StrikeListDocumentUser;
                            strikeListUsers.push(userDocument)
                        })
                        await Promise.all(strikeListUsers)
                        console.log('users found: ', strikeListUsers.length)
                        strikeListDocument.users = strikeListUsers
                    })
                console.log('users set in array: ', strikeListDocument.users.length)
                strikes.push(strikeListDocument)
            })
        })
    return strikes;
}

我的Firestore结构如下： / houses / {HouseID} / strikelists / {StrikeListID} / users / {UserID}

编辑：

我让它在其他班级工作。首先，我尝试让代码等待，然后返回它，但找不到解决方案。所以我改变了我的结构。每当接收到数据时，它将更新状态（必须位于同一文件中）。我正在使用mobx作为可观察对象。

ps：也可以从UI组件调用此代码并将其更改为useState挂钩。

现在看起来像这样：

@observable private _strikeLists: StrikeListDocument[] | undefined;

export const firestoreStrikeListSubscription = (houseId: string) => {
    firestore()
        .collection(FirebaseConstraints.HouseCollection)
        .doc(houseId)
        .collection(FirebaseConstraints.StrikeSubCollection)
        .onSnapshot(x => {
            x.forEach(x => {
                let strikeListDocument = x.data() as StrikeListDocument
                strikeListDocument.id = x.id;

                x.ref.collection(FirebaseConstraints.UserCollection).onSnapshot(
                    x => {
                        let strikeListDocumentUsers: StrikeListDocumentUser[] = []
                        x.forEach(y => {
                            let userDocument = y.data() as StrikeListDocumentUser;
                            strikeListDocumentUsers.push(userDocument)
                        })
                        const strikeList = this._strikeLists?.find(x => x.id == strikeListDocument.id)
                        if (strikeList)
                            strikeList.users = strikeListDocumentUsers
                    })
                this._strikeLists?.push(strikeListDocument)
            })
        })
}

Answer 1

<template>返回onSnapshot()。

请参见https://firebase.google.com/docs/reference/js/firebase.firestore.CollectionReference#onsnapshot

您可以尝试以下代码吗？

void

Firestore嵌套onSnapshot等待/异步

1 个答案: