Node.js Joi验证Sequelize自定义方法

我目前正试图通过Sequelize验证用户名是否已经存在，但是当前在将响应发送回客户机后，承诺将返回，这意味着Joi每次都认为用户名不存在。任何人都知道如何不让Joi过早地完成验证，并实际处理查询/返回正确的结果

schema.js

const Joi = require('joi')
const { User } = require('../models')

const validateUsername = (value, helpers) => {
    User.findOne({ where: { username: value } }).then(user => {
        if (user) {
            return helpers.error('username.exists')
        }
        return value
    })
}

const schema = Joi.object({
    body: {
        username: Joi.string().min(3).required().custom(validateUsername)
            .messages({
                'string.base': 'Invalid Username',
                'string.empty': 'Username Required',
                'string.min': 'Username Must Be At Least {#limit} Characters Long',
                'any.required': 'Username Required',
                'username.exists': 'Username Already In Use'
            })
    }
})

module.exports = schema

const options = {
    abortEarly: false,
    allowUnknown: true,
    stripUnknown: true
}

const validator = (schema) => {
    return (req, res, next) => {
        const { error } = schema.validate(req, options)
        const valid = error == null

        if (valid) {
            next()
        } else {
            const { details } = error;
            const errors = details.map(i => i.message)
            res.status(422).json({ errors })
        }
    }
}

module.exports = validator

validator.js

const Joi = require('joi')
const { User } = require('../models')

const validateUsername = (value, helpers) => {
    User.findOne({ where: { username: value } }).then(user => {
        if (user) {
            return helpers.error('username.exists')
        }
        return value
    })
}

const schema = Joi.object({
    body: {
        username: Joi.string().min(3).required().custom(validateUsername)
            .messages({
                'string.base': 'Invalid Username',
                'string.empty': 'Username Required',
                'string.min': 'Username Must Be At Least {#limit} Characters Long',
                'any.required': 'Username Required',
                'username.exists': 'Username Already In Use'
            })
    }
})

module.exports = schema

const options = {
    abortEarly: false,
    allowUnknown: true,
    stripUnknown: true
}

const validator = (schema) => {
    return (req, res, next) => {
        const { error } = schema.validate(req, options)
        const valid = error == null

        if (valid) {
            next()
        } else {
            const { details } = error;
            const errors = details.map(i => i.message)
            res.status(422).json({ errors })
        }
    }
}

module.exports = validator