如何在 Expressjs 中向用户显示此错误答案

【问题标题】：How do I display this Error to users in Expressjs如何在 Expressjs 中向用户显示此错误
【发布时间】：2020-09-16 02:31:09
【问题描述】：

我如何访问名字、姓氏、电子邮件和密码。示例：如果 firstname 存在，我如何访问并向用户显示错误，例如 firstname.msg。

[{"firstname":{"value":"","msg":"Firstname is required","param":"firstname","location":"body"},"lastname":{"value":"","msg":"Lastname must not contain number or symbol","param":"lastname","location":"body"},"email":{"value":"","msg":"Email is required","param":"email","location":"body"},"password":{"value":"","msg":"Password is required","param":"password","location":"body"}}]

【问题讨论】：

标签： node.js express ejs

【解决方案1】：

将数组保存到变量中，例如results。然后使用.map()遍历每个results对象，检查是否定义了msg属性；如果是，请将它们保存到新的 errors 数组中。如果没有定义msg 属性，则返回undefined。

然后我们使用.filter() 立即删除所有undefined 的元素，使errors 数组仅包含与results 数组中的msg 字段相等的字符串元素。

最后，我们正在检查errors 数组中是否有任何元素，如果有，则返回第一个元素（错误消息）；表达它会是这样的：

if(errors.length > 0) return res.status(400).json(errors[0]);.

这将始终返回函数遇到的第一个错误。

const results = [{"firstname":{"value":"","msg":"Firstname is required","param":"firstname","location":"body"},"lastname":{"value":"","msg":"Lastname must not contain number or symbol","param":"lastname","location":"body"},"email":{"value":"","msg":"Email is required","param":"email","location":"body"},"password":{"value":"","msg":"Password is required","param":"password","location":"body"}}]

const errors = results
    .map(({ firstname, lastname, email, password }) => {
        if(firstname.msg) return firstname.msg;
        else if (lastname.msg) return lastname.msg;
        else if (email.msg) return email.msg;
        else if (password.msg) return password.msg;
        else return;
    })
    .filter(error => error);

if(errors.length > 0) return errors[0];

【讨论】：