javascript - Firebase 简单查询给出错误 : "Converting circular structure to JSON at JSON.stringify"

Question

我正在尝试遍历/users 路径并将其加入我的 auth().listUsers 结果，但是这段代码:

https://github.com/QuantumInformation/svelte-fullstack-starter/blob/master/firebase_specific/functions/src/users.ts#L32

export async function getSomeUsers(amount: number) {
    try {
        const listUsersResult = await admin.auth().listUsers(amount)
        const parsedUsers = listUsersResult.users.map(stripUserSensitiveInfo).map(async user => {
            console.log("try read_______________" + user.uid)
            let userProfileSnapshot = await admin
                .database()
                .ref("users/" + user.uid)
                .once("value")

            console.log("end try read_______________" + user.uid)
            return { ...user, userProfileSnapshot }
        })

        return parsedUsers
    } catch (error) {
        console.error("Error listing users:", error)
        throw new Error("Error users" + error)
    }
}

给出这个错误

Converting circular structure to JSON at JSON.stringify () at stringify

但这段代码工作正常

export async function getSomeUsers(amount: number) {
    try {
        const listUsersResult = await admin.auth().listUsers(amount)


        const parsedUsers = listUsersResult.users.map(stripUserSensitiveInfo).map( user => {


            return 1
        })


        return parsedUsers
    } catch (error) {
        console.error("Error listing users:", error)
        throw new Error("Error users" + error)
    }
}

Answer 1

问题在于 map 中的嵌入式异步调用。运算符(operator)
为了使其工作，您需要等待每次迭代，这也是非常低效的。这是因为对于每个额外的查询，所花费的时间都会线性增加。
我的建议是以可扩展的方式转换整个逻辑。幸运的是，您的 listAllUsers() 就是这种情况。一次调用返回所有结果的函数

export async function getSomeUsers(amount: number) {
try {
    /**
     * fetch all the users with the provided limit
     */
    const allUsers = await admin.auth().listUsers(amount)
    /**
     * loop through the returned values and create a promise to fetch
     * Each of their document
     */
    const listUsersResult = allUsers.users.map(user => {
        return admin
            .database()
            .ref("users/" + user.uid)
            .once("value")
    })
    /**
     * When all the user documents have been fetched, iterare through them and deduce their values
     */
    const parsedUsers = await Promise.all(listUsersResult).then(docSnashots => {
        return docSnashots.map(snapshot => {
            console.log("end try read_______________" + snapshot.val())
            /**
             * The records need to be matched with the original values
             */
            const originalUserData = allUsers.users.find(u => u.uid === snapshot.key)
            return { ...originalUserData, ...snapshot.val() }
        })
    })
    return parsedUsers

} catch (error) {
    console.error("Error listing users:", error)
    throw new Error("Error users" + error)
}
}

注意 由于循环，此方法的计算密集度更高，但由于每个读取操作彼此独立，因此更省时。它可以在您确定读取操作总是需要很短的时间并且(也许)比循环的计算更节省资源的情况下进行修改