Sending null values in post request

[Lex-talionis]

Hi, when trying to sending a null value to a post endpoint, k6 converts null into '<nil>'. is there a way to fix this in my end?

[na--]

Can you post your code and tell us which k6 version you are using, since this seems like a bug, but I can't reproduce it. This code:

import http from "k6/http";

export default function () {
    let resp = http.post("https://httpbin.org/post", null);
    console.log(resp.body);
}

produces

{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Content-Length": "0", 
    "Host": "httpbin.org", 
    "User-Agent": "k6/0.25.1 (https://k6.io/)"
  }, 
  "json": null, 
  "url": "https://httpbin.org/post"
} 

which seems normal

[Lex-talionis]

Hi @na-- thanks for your quick response. Im sorry my last post wasnt clear at all

           let url = httpParams.url + "/api/v1/login";
           let payload = {
               username: "myusername",
               password: "mypassword",
               company_id: null ,
               vendor_id : null ,
               ldap_id : null ,
           };
           let params = {
               "Content-Type": "application/json"
           };
           let res = http.post(url, payload, params);

my response i get within the node api is

{
  company_id: '<nil>',
  ldap_id: '<nil>',
  password: 'mypassword',
  username: 'mypassword',
  vendor_id: '<nil>' 
}

[mstoykov]

This is duplicate of #878, so I am closing this.

For a quick fix you can useJSON.stringify(payload)(the issue above explains what is happening but as :

import http from "k6/http";

export default function () {
    let payload = {
        username: "myusername",
        password: "mypassword",
        company_id: null ,
        vendor_id : null ,
        ldap_id : null ,
    };
    let params = {
        "Content-Type": "application/json"
    };
    let resp = http.post("https://httpbin.org/post", JSON.stringify(payload), params);
    console.log(resp.body);
}

will get you:

 {
  "args": {},
  "data": "{\"username\":\"myusername\",\"password\":\"mypassword\",\"company_id\":null,\"vendor_id\":null,\"ldap_id\":null}",
  "files": {},
  "form": {},
  "headers": {
    "Content-Length": "99",
    "Host": "httpbin.org",
    "User-Agent": "k6/0.26.0-dev (https://k6.io/)"
  },
  "json": {
    "company_id": null,
    "ldap_id": null,
    "password": "mypassword",
    "username": "myusername",
    "vendor_id": null
  },
  "origin": "46.233.49.37, 46.233.49.37",
  "url": "https://httpbin.org/post"
}

I have also opened new issue to fix the problem when urlencoding: #1185

[Lex-talionis]

@mstoykov thanks for your response i did have a check on existing issues and couldn't find a similar one, obviously i didn't look hard enough.

[na--]

Don't worry @Lex-talionis, the issue wasn't easy to find since it stated the same problem in a different way... We just knew it because we've hit it before, and even then, your issue told us something that we didn't know before about the way null values are encoded, which we'd like to fix now, thus the new issue. The other reason we knew about the old issue is because we're currently investigating how to add a new and better HTTP API in k6 that would both be more flexible, and also solve issues like this that such confusion and frustration.

[aniketRaj-goPlus]

Use blank string instead of null in your json format like this:

import http from "k6/http";

export default function () {
    let payload = {
        username: "myusername",
        password: "mypassword",
        company_id: "" ,
        vendor_id : "" ,
        ldap_id : "" ,
    };}