nodejs - first argument must be a string or Buffer - when using response.write with http.request

Question

I'm simply trying to create a node server that outputs the HTTP status of a given URL.

When I try to flush the response with res.write, I get the error: throw new TypeError('first argument must be a string or Buffer');

But if I replace them with console.log, everything is fine (but I need to write them to the browser not the console).

The code is

var server = http.createServer(function (req, res) {
    res.writeHead(200, {"Content-Type": "text/plain"});

    request({
        uri: 'http://www.google.com',
        method: 'GET',
        maxRedirects:3
    }, function(error, response, body) {
        if (!error) {
            res.write(response.statusCode);
        } else {
            //response.end(error);
            res.write(error);
        }
    });     

    res.end();
});
server.listen(9999);

I believe I should add a callback somewhere but pretty confused and any help is appreciated.

Note that in the simplest case when parsing json in node (so, let args = JSON.parse(incomingText)) this means very simply that the argument was missing. So you later try args.name and name is just not present in the incoming Text. — Fattie
– Fattie, Commented Jul 31, 2022 at 16:50

Alexander Mills · Accepted Answer · 2022-06-29 23:25:47Z

58

I get this error message and it mentions options.body

I had this originally

request.post({
    url: apiServerBaseUrl + '/v1/verify',
    body: {
        email: req.user.email
    }
});

I changed it to this:

request.post({
    url: apiServerBaseUrl + '/v1/verify',
    body: JSON.stringify({
        email: req.user.email
    })
});

and it seems to work now without the error message...seems like bug though. I think this is the more official way to do it:

 request.post({
        url: apiServerBaseUrl + '/v1/verify',
        json: true,
        body: {
            email: req.user.email
        }
    });

edited Jun 29, 2022 at 23:25

answered Dec 20, 2015 at 7:34

Alexander Mills

102k167 gold badges549 silver badges936 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Nuno Tomas Over a year ago

Your problem is different, body is expected by default to be a string or Buffer. You can also change it (to be json serializable) adding json:true to options. Eg: request.post({ url: apiServerBaseUrl + '/v1/verify', body: { email: req.user.email }, json: true })

bsorrentino Over a year ago

You could use this to avoid stringify javascript request.post({ url: apiServerBaseUrl + '/v1/verify', json: { email: req.user.email } }

loganfsmyth · Accepted Answer · 2013-02-12 15:29:44Z

54

response.statusCode is a number, e.g. response.statusCode === 200, not '200'. As the error message says, write expects a string or Buffer object, so you must convert it.

res.write(response.statusCode.toString());

You are also correct about your callback comment though. res.end(); should be inside the callback, just below your write calls.

edited Feb 12, 2013 at 15:29

answered Feb 12, 2013 at 15:19

loganfsmyth

162k31 gold badges349 silver badges259 bronze badges

1 Comment

umutm Over a year ago

Yes, that did the trick. As a nodejs newbie, didn't know that and thanks so much.

Ronan Boiteau · Accepted Answer · 2019-10-10 00:55:03Z

33

Request takes a callback method, its async! So I am assuming, by the time the callback is executed the res.end() might get called. Try closing the request within the callback.

edited Oct 10, 2019 at 0:55

Ronan Boiteau

10.3k7 gold badges39 silver badges62 bronze badges

answered Feb 12, 2013 at 15:20

Gaurav Agarwal

14.9k4 gold badges31 silver badges42 bronze badges

3 Comments

umutm Over a year ago

Did that and also added .toString. Thanks much.

umutm Over a year ago

Seems like I forgot to. Just did it. Thx.

Gaurav Agarwal Over a year ago

@umutm There are more well written and elaborate answers, you should probably accept one of them; making it visible to anyone coming to this question.

freakish · Accepted Answer · 2013-02-12 15:20:09Z

14

Well, obviously you are trying to send something which is not a string or buffer. :) It works with console, because console accepts anything. Simple example:

var obj = { test : "test" };
console.log( obj ); // works
res.write( obj ); // fails

One way to convert anything to string is to do that:

res.write( "" + obj );

whenever you are trying to send something. The other way is to call .toString() method:

res.write( obj.toString( ) );

Note that it still might not be what you are looking for. You should always pass strings/buffers to .write without such tricks.

As a side note: I assume that request is a asynchronous operation. If that's the case, then res.end(); will be called before any writing, i.e. any writing will fail anyway ( because the connection will be closed at that point ). Move that line into the handler:

request({
    uri: 'http://www.google.com',
    method: 'GET',
    maxRedirects:3
}, function(error, response, body) {
    if (!error) {
        res.write(response.statusCode);
    } else {
        //response.end(error);
        res.write(error);
    }
    res.end( );
});

answered Feb 12, 2013 at 15:20

freakish

57k12 gold badges141 silver badges181 bronze badges

1 Comment

umutm Over a year ago

Thank so much for the answer and the detailed info. And, yes, I have moved the res.end into the handler. I have accepted @loganfsmyth as it was earlier. Thx again.

Mohsin Muzawar · Accepted Answer · 2017-04-26 04:38:34Z

1

if u want to write a JSON object to the response then change the header content type to application/json

response.writeHead(200, {"Content-Type": "application/json"});
var d = new Date(parseURL.query.iso);
var postData = {
    "hour" : d.getHours(),
    "minute" : d.getMinutes(),
    "second" : d.getSeconds()
}
response.write(postData)
response.end();

answered Apr 26, 2017 at 4:38

Mohsin Muzawar

1,2129 silver badges9 bronze badges

Comments

Prajith P · Accepted Answer · 2018-03-16 10:04:47Z

1

And there is another possibility (not in this case) when working with ajax(XMLhttpRequest), while sending information back to the client end you should use res.send(responsetext) instead of res.end(responsetext)

answered Mar 16, 2018 at 10:04

Prajith P

691 silver badge2 bronze badges

Comments

Mr.X · Accepted Answer · 2018-05-03 19:24:20Z

1

Although the question is solved, sharing knowledge for clarification of the correct meaning of the error.

The error says that the parameter needed to the concerned breaking function is not in the required format i.e. string or Buffer

The solution is to change the parameter to string

breakingFunction(JSON.stringify(offendingParameter), ... other params...);

or buffer

breakingFunction(BSON.serialize(offendingParameter), ... other params...);

answered May 3, 2018 at 19:24

Mr.X

31.7k27 gold badges150 silver badges231 bronze badges

Comments

A. PRABIN SARAB · Accepted Answer · 2020-01-11 10:29:22Z

0

The first argument must be one of type string or Buffer. Received type object

 at write_

I was getting like the above error while I passing body data to the request module.

I have passed another parameter that is JSON: true and its working.

var option={
url:"https://myfirstwebsite/v1/appdata",
json:true,
body:{name:'xyz',age:30},
headers://my credential
}
rp(option)
.then((res)=>{
res.send({response:res});})
.catch((error)=>{
res.send({response:error});})

answered Jan 11, 2020 at 10:29

A. PRABIN SARAB

412 bronze badges

Collectives™ on Stack Overflow

nodejs - first argument must be a string or Buffer - when using response.write with http.request

8 Answers 8

2 Comments

1 Comment

3 Comments

1 Comment

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

8 Answers 8

2 Comments

1 Comment

3 Comments

1 Comment

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related