When I used Postman to add value into my student object array? It gave me the error like this

Question

Could someone have any solution to solve this error?

I used Postman to add new student into students, but when it ran to req.on("data", function (chunk) {…}. It gave me the error which is like below.

create server or import library code which is like http, url,... I already wrote them in my code. The problem here is this function.

Thanks everyone due to watch my post.

function addStudent(req, res) {
    var body = "";

    req.on("data", function (chunk) {   // error from this line
        body += chunk;
    });

    req.on("end", function () {
        var post = url.parse("/?" + body, true);

        let name = post.query.name;
        let gender = post.query.gender;

        students.push({ name: name, gender: gender });
    });

    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end({ success: "true" });
}

node:_http_outgoing:802
    throw new ERR_INVALID_ARG_TYPE(
    ^

TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be of type string or an instance of Buffer or Uint8Array. Received an instance of Object
    at new NodeError (node:internal/errors:387:5)
    at write_ (node:_http_outgoing:802:11)
    at ServerResponse.end (node:_http_outgoing:934:5)
    at addStudent (D:\TDTU\Third_Year\HK1\Advanced_Web_Programming\Tasks\DAY2\520H0549\exercise3.js:27:13)
    at Server.<anonymous> (D:\TDTU\Third_Year\HK1\Advanced_Web_Programming\Tasks\DAY2\520H0549\exercise3.js:40:12)
    at Server.emit (node:events:513:28)
    at parserOnIncoming (node:_http_server:1013:12)
    at HTTPParser.parserOnHeadersComplete (node:_http_common:117:17) {
  code: 'ERR_INVALID_ARG_TYPE'
}

Colorado Akpan · Answer 1 · 2022-09-17T14:01:51.923

0

The error above shows that you're trying to assign an object to a string

In your case, you defined the var body to be a type of string, while in your callback function, an object was received.

to fix that, if you're unsure of the type of data/argument you'll be receiving in your callback, you can set the var body to be type any, like the code below;

    function addStudent(req, res) {
    var body = []; //this will set the data type to any, so you can push in any datatype/argument to it.

    req.on("data", function (chunk) {   // error from this line
        body.push(...chunk);
    });

    req.on("end", function () {
        var post = url.parse("/?" + body, true);

        let name = post.query.name;
        let gender = post.query.gender;

        students.push({ name: name, gender: gender });
    });
res.writeHead(200, { "Content-Type": "application/json" });
return res.end({ success: "true" });
}

edited Sep 17 '22 at 14:01

answered Sep 17 '22 at 12:51

Colorado Akpan

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1
12

Thank you for answering my post. But it didn't work. I did remove like you said, but it still gave that error – Yoru Sep 17 '22 at 13:02
how about you assign the body as an new object instead of appending it, since from your code about the body object doesn't exist before within the function. like example, body = chunk or use body.push(...chunk) – Colorado Akpan Sep 17 '22 at 13:21
have edited the above code to use object destructuring method – Colorado Akpan Sep 17 '22 at 13:25
it's still the same. – Yoru Sep 17 '22 at 13:33
I will give you a picture which shows how I use postman to send data – Yoru Sep 17 '22 at 13:34
alright, i will be expecting – Colorado Akpan Sep 17 '22 at 13:39
here https://ibb.co/9yBhfcP – Yoru Sep 17 '22 at 13:39
Thank you for helping me. I think I already solved the problem in this post https://stackoverflow.com/questions/61865764/the-chunk-argument-must-be-of-type-string-or-an-instance-of-buffer – Yoru Sep 17 '22 at 13:56
orh i see, you're welcome – Colorado Akpan Sep 17 '22 at 14:01
I made it. But simply, I just use res.write(JSON.stringify({ success: "true" })) instead of res.end({ success: true}). And it worked – Yoru Sep 17 '22 at 14:01
alright that was cool one. but why not using express? it can be much simpler and easier – Colorado Akpan Sep 17 '22 at 14:03
I know. But it is my homework request in advanced web programming class. So I must use nodejs to solve the problem without using any module installed by package manager – Yoru Sep 17 '22 at 14:08

When I used Postman to add value into my student object array? It gave me the error like this

1 Answers1