Postman OAuth 2.0 pre-request with 'password' grant type

postman-oauth-pre-request.js

const postRequest = {
  url: pm.collectionVariables.get('token_url'),
  method: 'POST',
  header: 'Content-Type:application/x-www-form-urlencoded; charset=utf-8',
  body: {
    mode: 'urlencoded',
    urlencoded: [
      {
        key: 'client_id',
        value: pm.collectionVariables.get('client_id'),
      },
      {
        key: 'client_secret',
        value: pm.environment.get('client_secret'),
      },
      {
        key: 'scope',
        value: pm.environment.get('scope'),
      },
      {
        key: 'username',
        value: pm.collectionVariables.get('user'),
      },
      {
        key: 'password',
        value: pm.collectionVariables.get('api_key'),
      },
      {
        key: 'grant_type',
        value: 'password',
      },
      {
        key: 'auth_method',
        value: 'password',
      },
    ],
  },
};

var getToken = true;

if (!pm.environment.get('access_token_expiry') || !pm.environment.get('current_access_token')) {
  console.log('Token or expiry date are missing');
} else if (pm.environment.get('access_token_expiry') <= new Date().getTime()) {
  console.log('Token is expired');
} else {
  getToken = false;
  console.log('Token and expiry date are all good');
}

if (getToken === true) {
  pm.sendRequest(postRequest, function (err, res) {
    console.log(err ? err : res.json());
    if (err === null) {
      console.log('Saving the token and expiry date');
      var responseJson = res.json();
      pm.environment.set('current_access_token', responseJson.access_token);

      var expiryDate = new Date();
      expiryDate.setSeconds(expiryDate.getSeconds() + responseJson.expires_in);
      pm.environment.set('access_token_expiry', expiryDate.getTime());
    }
  });
}