Unable to read "client_id" even it was provided in code

[weilies]

i had my code as below. i checked many time and ensure "client_id" exists (for security reason, i replace them with "..." in sample code below

async function makePOSTRequest() {
  // POST SAP
  const body = JSON.stringify({
		user_id: "...",
		client_id: "...",
		token_url: "https://api12preview.sapsf.eu:443/oauth/token",
		private_key: "...",
	});

  const options = {
    host: 'xxx.com',
    path: '/idp',
    method: 'POST',
    port: 443,
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
      'Content-Length': Buffer.byteLength(body) // Set Content-Length header
    }
  }; 
  
  
  return new Promise((resolve, reject) => {
    const req = https.request(options, res => {
      let rawData = '';

      res.on('data', chunk => {
        rawData += chunk;
      });

      res.on('end', () => {
        try {
          resolve(JSON.parse(rawData));
        } catch (err) {
          reject(new Error(err));
        }
      });
    });

    req.on('error', err => {
      reject(new Error(err));
    });

    req.write(body); // Write the request body
    req.end();
  });
}

when i run the program it returns

node index.js
{
  errorHttpCode: '500',
  errorMessage: 'Parameter "client_id" is required in the OAuth request'
}

i am new to this package. kindly comment and thanks

[SaiKumar2121]

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[JimmyDaddy]

@weilies
Your content-type is application/x-www-form-urlencoded, use JSON.stringify to format request body isn't correct.
You should replace

const body = JSON.stringify({
  user_id: "...",
  client_id: "...",
  token_url: "https://api12preview.sapsf.eu:443/oauth/token",
  private_key: "...",
});

to

const querystring = require('querystring');
...

const body = querystring.stringify({
  user_id: "...",
  client_id: "...",
  token_url: "https://api12preview.sapsf.eu:443/oauth/token",
  private_key: "...",
});

or

const FormData = require('form-data');

...

const body = new FormData();
form.append('user_id', '...');
form.append('client_id', '...');
...

OOOOR you can concat the body string by yourself like follow format
user_id=...&client_id=...&token_url=https%3A%2F%2Fapi12preview.sapsf.eu%3A443%2Foauth%2Ftoken&private_key=...