Postman Pre-request Script to automatically get a Bearer Token from OAuth and save it for reuse

postman-pre-request-script.js

const moment = require('moment');

const getAuthorization = {
    url: pm.environment.get("tokenBaseURL") + '/ia2oauth/token',
    method: 'POST',
    header: {
        'Content-Type': 'application/x-www-form-urlencoded'
    },
    body: {
        mode: 'urlencoded',
        urlencoded: [
            {key: 'grant_type', value: 'password'},
            {key: 'username', value: pm.globals.get("user-id")},
            {key: 'password', value: pm.globals.get("user-pw")},
            {key: 'client_secret', value: pm.environment.get("client_secret")},
            {key: 'client_id', value: pm.environment.get("client_id")},
            {key: 'accountType', value: 'USER'} 
        ]
    }
};

var getToken = true;

if (!_.has(pm.environment.toObject(), 'AccessTokenExpiry') 
    || !_.has(pm.environment.toObject(), 'authorization')
    || pm.environment.get('AccessTokenExpiry') <= moment().valueOf()) {
} else {
    getToken = false;
}

console.log('getToken: ' + getToken);

if (getToken) {
    pm.sendRequest(getAuthorization, (err, res) => {
        console.log('res: ' + res.json());
        if (err === null) {
            pm.environment.set('authorization', `Bearer ${res.json().access_token}`);
            console.log('authorization: ' + pm.environment.get("authorization"));
            
            var expiryDate = moment().add(res.json().expires_in, 's').valueOf();
            pm.environment.set('AccessTokenExpiry', expiryDate);
        } else {
            console.log('error: ' + err);
        }
    });
}