Question

我正在创建一个Express终结点，用于验证用户名/密码是否在我的数据库（json文件）中

router.post('/login', (req, res) => {
    let userData = req.body;
    if (validateEmailAndPassword(userData.username, userData.password) {
        res.send(userData);
    } else {
        res.status(401).send({ error: "Username/Password combination is incorrect." });
    }
})

const validateEmailAndPassword = (username, password) => {
    let validCreds = false;
    fs.readFile('db/users.json', 'utf8', (err, data) => {
        if (data) {
            const stream = JSON.parse(data);
            const usersFound = stream.filter(info => {
            if (info.username === username && info.password ===password) { return true; }
            })
        if (usersFound.length >= 1) { validCreds = true; }
        return validCreds;

        } else {
            throw Error(err);
        }
    })
}

第一个代码块第3行中的

'validateEmailAndPassword（userData.username，userData.password）'在if条件下返回'undefined'，因为它是异步的。

同步解析'validateEmailAndPassword（userData.username，userData.password）'的最佳方法是什么，以便在不使用readFileSync的情况下获得true / false值？

谢谢！

Answer 1

使用async await和promises

router.post('/login', async(req, res) => {
    let userData = req.body;
    if (await validateEmailAndPassword(userData.username, userData.password)) {
        res.send(userData);
    } else {
        res.status(401).send({ error: "Username/Password combination is incorrect." });
    }
})

const validateEmailAndPassword = (username, password) => {
    let validCreds = false;
    return new Promise(resolve => {
    fs.readFile('db/users.json', 'utf8', (err, data) => {
        if (data) {
            const stream = JSON.parse(data);
            const usersFound = stream.filter(info => {
            if (info.username === username && info.password ===password) { return true; }
            })
        if (usersFound.length >= 1) { validCreds = true; }
        resolve(validCreds);
        return validCreds;

        } else {
            throw Error(err);

        }
    })
    })
}

tada

Answer 2

要扩展@Estradiaz答案...

听起来您想同步使用它，所以您可以使其同步而不是使其异步并等待它：

readFile-> readFileSync

const validateEmailAndPassword = (username, password) => {
    let validCreds = false;
    var data = fs.readFileSync('db/users.json', 'utf8');
    if (data) {
        const stream = JSON.parse(data);
        const usersFound = stream.filter(info => {
            if (info.username === username && info.password === password)
                return true;
        });

        if (usersFound.length >= 1)
            validCreds = true;

        return validCreds;

    } else {
        throw Error(err);
    }
}

如何使用异步readFile调用来解析为if条件（快速）中的值

2 个答案: