保存用户前如何检查电子邮件是否存在

Question

I'm starting nodeJS / MongoDB and I'm trying to create a simple auth API. I began by the SignIn function, but I have some difficulties with async functions when I check my form values. I try to check every values before save a row in database. So I check password and email format, and my difficulties begin when I want to check if the email already exist.

Here you can see my function called when I submit my form :

export function signUp(req, res) {
    const { email, password, confirmPassword } = req.body || '';
    const allFields = { email, password, confirmPassword };

    let errors = {};
    Object.keys(allFields).forEach(async field => {
        const value = allFields[field];

        if (value === '') {
            errors = {...errors, [field]: 'Ce champ est requis'}
        } else {
            if (field === 'email') {
                if (!checkEmailFormat(value)) {
                    errors = {...errors, [field]: 'Le format de mail n\'est pas valide'}
                } else {
                    const { error, exist } = await checkEmailExist(value);
                    if (exist) {
                        console.log(exist);
                        console.log(error);
                        errors = {...errors, ...error};
                    }
                }
            }
            if (field === 'password' && password !== '' && password < 6) {
                errors = {...errors, [field]: 'Le mot de passe doit contenir plus de 6 caractères'}
            }
        }
    });

    console.log(errors);
    console.log(Object.keys(errors).length);
    console.log('--------------------');

    // Retour des erreurs vers le FRONT ou Save de l'user
    if (Object.keys(errors).length > 0) {
        console.log(errors);
        res.json({ errors });
    } else {
        ...Save my row in db
    }
}

And here my function checkEmailExist who check in db

const checkEmailExist = async (value) => {
    const { error, exist } = await User.findOne({'email': value}).exec()
        .then(user => {
            let res = {};
            if (user) {
                res = { error: { 'email': "Cet adresse email n'est pas disponible" }, exist: true };
            } else {
                res = { error: { 'email': "" }, exist: false };
            }
            return res;
        })
        .catch(err => console.log(err))

    return { error, exist };
}

My goal is to get the error returned from the checkEmailExist function, and send this errors to the FRONT with the others errors. But findOne is an async function and the query is always pending when I check my array of errors if (Object.keys(errors).length > 0) { . So the user can be saved with and existing email.

How can I properly check if email exist before saving the user ?

Thanks

Answer 1

Solution one : use checkEmailExist when user type the email in textfield using onchange or leaving the email field.

Solution two : Use ES6 ASYNC/AWAIT to hold the flow until return true or false from checkEmailExist method.

REMOVE .then query... why do you need then if your are using await...

const checkEmailExist = async (value) => {
    const { error, exist } = await User.findOne({'email': value}).exec()
    return { error, exist };
}

Answer 2

looks like you're mixing a .then with an await. i confess to not being an expert on async/await here, especially when mixed with promises, but could your checkEmailExist function look like:

const checkEmailExist = async (value) => {
    const user = await User.findOne({'email': value}).exec()
        .catch(err => console.log(err))

    let res = {};
    if (user) {
        res = { error: { 'email': "Cet adresse email n'est pas disponible" }, exist: true };
    } else {
        res = { error: { 'email': "" }, exist: false };
    }
    return res;
}

?

not sure if it makes a difference, but mixing the await and the then seems like it might give you unexpected results

Answer 3

The problem at Object.keys(allFields).forEach(async field . The code inside foreach is async function, so it intermediately execute and the next line of code not waiting for it to end. You should make signUp async : export async function signUp and replace forEach with a regular loop:

for (const field in allFields) {
   ...
}