How to specify content type for individual formdata elements

Grafana k6 OSS Support
1

Is it possible to use something like Blob in K6, in order to have form data elements with different content types? i.e one is a file (easy enough), another is json. Each would have their own respective content types.

Something like:

const fd = new FormData();
   fd.append('bookInfo', new Blob([JSON.stringify({
        name: "Book",
        quantity: "12"
    })], {
        type: "application/json"
    }));
  fd.append('testFile', http.file(someFile, 'somefil.txt', 'application/octet-stream'));
2

Hi @jclarknet, welcome to the forum and sorry for the slow reploy :bowing_man:

It seems to not have been documented but you can just append an object with keys:

  • data - which will be the data you want
  • filename - you can skip that if you don’t want filename set.
  • content_type - with the content type you want, if not provided it will be application/octet-stream

You can see it done here

3

Hi, did you find a solution for this? because I am facing the same problem, I followed the solution provided by @mstoykov , which worked but I got an error , I will add my code here as well.

const fd = new FormData();
    fd.append("version", number);
    fd.append("file",{data: new http.file(binFile), filename: 'test.bin',content_type: 'application/octet-stream'});
    fd.append("firmwareId", "b5b51538-72b2-433f-b873-d65abf04b4b2");```

OUPUT:

execution: local
script: tester.js
output: -

scenarios: (100.00%) 1 scenario, 1 max VUs, 10m30s max duration (incl. graceful stop):
* default: 1 iterations for each of 1 VUs (maxDuration: 10m0s, gracefulStop: 30s)

INFO[0017] number of devices: 1 organizationName: Pr Organazation t1 source=console
ERRO[0018] Uncaught (in promise) TypeError: Value is not a constructor

 ✓ status code: 200
4

Hi @Zahida.Parveen,

This topic is 1year+ old and unlikely to get a new response.

Also, your errors seem unlikely to be directly related to the topic at hand.

I would recommend opening a new topic with more info in order for somebody to be able to help you.

5

Hey @Zahida.Parveen , it’s been a while since I wrote this, but below is the code that worked for me:

fd.append('someFile', http.file(someFile, 'myfile.bin', 'application/octet-stream'));
 
const res = http.post('https://someurl', fd.body(), {
    headers: { 'Content-Type': 'multipart/form-data; boundary=' + fd.boundary },
});
3 Likes
6

@jclarknet Thankyou…