Auto-Increment ID's for OAuth2.0 Access Tokens in Postman

Question

I am trying to implement an auto-incrementing ID to append to my token name in order to differentiate better between tokens retrieved at different times.

I was able to get as far as figuring out to create a variable called tokenCount and autoincrement it in the tests tab using this code:

let tokenCount = pm.collectionVariables.get("tokenCount");
tokenCount++;
pm.collectionVariables.set("tokenCount", tokenCount);

However, this only increments when I send my request; not when I retrieve a new access token. Is there any way that I can run this code upon the access token retrieval instead?

Answer 1

The following is an example of a pre-request script that authenticates against Microsoft using OAuth 2.0.

You will need to change the body to match the grant type you are using.

let currentDateTime = Date.now();
let tokenExpiry = pm.environment.get("bearerTokenExpiresOn")
// console.log("currentDateTime: " + currentDateTime);
// console.log("tokenExpiry: " + tokenExpiry);
if (!pm.environment.get("bearerToken") || currentDateTime > tokenExpiry) {
    pm.test("Pre-request check for Environment Variables", function () {
        let vars = ['clientId', 'clientSecret', 'tenantId', 'username', 'password', 'scope'];
        vars.forEach(function (item) {
            // console.log(item);
            pm.expect(pm.environment.get(item), item + " variable not set").to.not.be.undefined;
            pm.expect(pm.environment.get(item), item + " variable not set").to.not.be.empty;
        });
        pm.sendRequest({
            url: 'https://login.microsoftonline.com/' + pm.environment.get("tenantId") + '/oauth2/v2.0/token',
            method: 'POST',
            header: 'Content-Type: application/x-www-form-urlencoded',
            body: {
                mode: 'urlencoded',
                urlencoded: [
                    { key: "client_id", value: pm.environment.get("clientId"), disabled: false },
                    { key: "scope", value: pm.environment.get("scope"), disabled: false },
                    { key: "username", value: pm.environment.get("username"), disabled: false },
                    { key: "password", value: pm.environment.get("password"), disabled: false },
                    { key: "client_secret", value: pm.environment.get("clientSecret"), disabled: false },
                    { key: "grant_type", value: "password", disabled: false },
                ]
            }
        }, function (err, res) {
            if (err) {
                console.log(err);
            } else {
                pm.test("Pre-request Microsoft login Status code is 200", () => {
                    pm.expect(res).to.have.status(200);
                    let resJson = res.json();
                    // console.log(resJson);
                    let tokenName = pm.environment.get("tokenName")
                    let tokenCount = pm.environment.get("tokenCount");
                    tokenCount++;
                    pm.environment.set(tokenName + tokenCount, resJson.id_token);
                    pm.environment.set("bearerTokenExpiresOn", Date.now() + resJson.expires_in * 1000);
                    pm.environment.set("tokenCount", tokenCount);
                    // console.log("bearerTokenExpiresOn: " + pm.environment.get("bearerTokenExpiresOn"));
                });
            }
        });
    });
};

These are the added lines that deal with the auto-incrementing number.

let tokenName = pm.environment.get("tokenName")
let tokenCount = pm.environment.get("tokenCount");
tokenCount++;
pm.environment.set(tokenName + tokenCount, resJson.id_token);
pm.environment.set("tokenCount", tokenCount);

You will need Environment variables called tokenName and tokenCount. You will also need to initialise the tokenCount. For example 000.