node.js - 如何使用异步 readFile 调用解析为 if 条件中的值 (Express)

Question

我正在创建一个 Express 端点，在其中验证用户名/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 条件中返回“未定义”，因为它是异步的。

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

提前致谢!

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);

        }
    })
    })
}

多田