Custom validation async validator

[TheDhejavu]

const schema = Joi.object().keys({
        firstName: Joi.string().required(),
        lastName: Joi.string().required(),
        password: Joi.string().min(6).pattern(new RegExp('^[a-zA-Z0-9]{3,30}$')).required(),
        email: Joi.string().email().required().custom(async (value, helpers)=>{
            const emailExist = await User.find({ email: value })
            if (!emailExist) {
                return helper.message("Email already exist")

            } else {
                return true
            }
        }),
    });

    await schema.validateAsync(req.body, {abortEarly: false});

I have tried every possible way to make the above code work without using async but still doesn't work.

Any technical explanation on why JOi decides to support only sync custom validator

[brianle1301]

@TheDhejavu Use any.external()

[niteshrawat1995]

@brianle1301 Can you please share code snippet for it?

[bnymn]

Can we use the combination of string() and any()?

[jonyeezs]

FYI: The current documentation on external is much to be desired. It doesn't have a very good helper nor information on how to return an invalid schema (throw doesn't seem to work nicely). There's this PR that will make external work very similar to custom #2773