javascript - 为什么我在运行 mysql 查询时在 Node JS 中收到 'Converting circular structure to JSON' 错误？

Question

我正在做一个 mysql 查询来选择表中的所有数据(名称 LOGIN)和

https://localhost:2000/select and the params to be passed in the req.body is the table_name value is login and when i hit the api using postman, it returns an empty set with consolelog says,

TypeError: Converting circular structure to JSON
    at JSON.stringify (<anonymous>)
    at Object.selecting (/home/andiswamy/Documents/fuDDie/shayam/dbConnection.js:67:23)
    at process._tickCallback (internal/process/next_tick.js:68:7)

我的代码是:

router.get('/select', async (req, res) =>
{   
    let table_name =  req.headers.table_name;
    try {
        let inserting = await db.selecting(table_name);
        console.log(inserting);

        res.send(stringify(inserting));
        res.end();
    } catch(err) {
        console.log(err);
    }
});

async function selecting(table_name) {
    try {
        let result = await testDB.query(`SELECT * FROM ${table_name}`);
        console.log(typeof result);
        result = JSON.stringify(result);
        return result;
    } catch (e) {
        return e;
    }
}

Answer 1

let room = {
  number: 23
};

let meetup = {
  title: "Conference",
  participants: ["john", "ann"]
};

meetup.place = room;       // meetup references room
room.occupiedBy = meetup; // room references meetup

JSON.stringify(meetup); // Error: Converting circular structure to JSON

请参阅上面的示例，当您将两个对象相互引用并尝试将它们字符串化时，就会发生此错误。