Expressjs不返回所有属性从msnodesqlv8 Err对象

在下面的代码中，我通过尝试连接到不SQL Server上存在的数据库引起错误（图）。

const sql = require("msnodesqlv8");
const express = require("express");
const app = express();

// Start server and listen on http://localhost:8081/
const server = app.listen(8081, function () {
    console.log("Server listening on port: %s", server.address().port)
});

const connectionString = "Server=.;Database=DatabaseThatDoesNotExist;Trusted_Connection=Yes;Driver={SQL Server Native Client 11.0}";
const sql = "SELECT * FROM dbo.Table1";

app.get('/', function (req, res)
{
    sql.query(connectionString, sql, (err, recordset) => {
        if(err)
        {
            console.log(err);
            res.status(500).send(err);
            return;
        }

        // else
        res.json(recordset);
    });
})

console.log(err);的结果列出了与四个属性（代码，消息，SQLSTATE和堆栈）的错误的对象：

Array(2) [Error: [Microsoft][SQL Server Native Client 11.0][…, Error: [Microsoft][SQL Server Native Client 11.0][…]
codefile.js:33
length:2
__proto__:Array(0) [, …]
0:Error: [Microsoft][SQL Server Native Client 11.0][SQL Server]Login failed for user 'DOMAIN\USER'.
code:18456
message:"[Microsoft][SQL Server Native Client 11.0][SQL Server]Login failed for user 'DOMAIN\USER'."
sqlstate:"28000"
stack:"Error: [Microsoft][SQL Server Native Client 11.0][SQL Server]Login failed for user 'DOMAIN\USER'."
__proto__:Object {constructor: , name: "Error", message: "", …}
1:Error: [Microsoft][SQL Server Native Client 11.0][SQL Server]Cannot open database "MyDatabase" requested by the login. The login failed.
code:4060
message:"[Microsoft][SQL Server Native Client 11.0][SQL Server]Cannot open database "MyDatabase" requested by the login. The login failed."
sqlstate:"42000"
stack:"Error: [Microsoft][SQL Server Native Client 11.0][SQL Server]Cannot open database "MyDatabase" requested by the login. The login failed."
__proto__:Object {constructor: , name: "Error", message: "", …}

然而，res.status(500).send(err);（在客户端看到的）的结果只包含两个属性（SQLSTATE和代码）：

[
    {
        "sqlstate": "28000",
        "code": 18456
    },
    {
        "sqlstate": "42000",
        "code": 4060
    }
]

我该如何表达也返回消息和堆栈属性？

问题是，Error没有枚举的领域，因此message和stack没有得到序列化到JSON。

见this question办法序列化的错误对象。

对于你的情况迅速解决：res.status(500).send({message: err.message, stack: err.stack});

但是，这当然是不可扩展的。更好的办法是配置json replacer for express：

app.set('json replacer', replaceErrors);

并通过@乔纳森 - lonowski使用来自链接的问题优异的答案替代品实现：

function replaceErrors(key, value) {
  if (value instanceof Error) {
    var error = {};

    Object.getOwnPropertyNames(value).forEach(function (key) {
        error[key] = value[key];
    });

    return error;
  }
  return value;
}