gtm-server-side-example-visitor-stitching-client.js

const claimRequest = require('claimRequest');
const getRequestBody = require('getRequestBody');
const getRequestPath = require('getRequestPath');
const getRequestQueryParameters = require('getRequestQueryParameters');
const getTimestamp = require('getTimestampMillis');
const returnResponse = require('returnResponse');
const setResponseBody = require('setResponseBody');
const setResponseStatus = require('setResponseStatus');
const getRequestMethod = require('getRequestMethod');
const getContainerVersion = require('getContainerVersion');
const JSON = require('JSON');
const log = require('logToConsole');
const setResponseHeader = require('setResponseHeader');
const sendHttpRequest = require('sendHttpRequest');
const templateDataStorage = require('templateDataStorage');

if (getRequestPath() === '/stitch') {
    claimRequest();

    // returns a failure message and status code
    const fail = msg => {
        setResponseStatus(500);
        setResponseBody(msg);
        returnResponse();
    };
    var params;
    const reqMethod = getRequestMethod();
    if (reqMethod === "GET") { // expects a request like https://<your domain>/stitch?id=the_id_to_stitch&async_response=0
        params = getRequestQueryParameters(); // gets query params into object like { id: "12345", async_response: "0" }
    } else if (reqMethod === "POST") {
        params = JSON.parse(getRequestBody()); // in case we get the data in a POST body, we simply take the JSON payload
    }
    log("Got the following parameters from the " + reqMethod + " request:");
    log(params);
    const uid = params.id; // get the user ID
    if (!uid) {
        fail("no user ID provided!");
    }

    const containerVersion = getContainerVersion();
    const containerId = containerVersion.containerId;
    // to make transport to another pubsub message frictionless, we provide all attributes as strings instead of Booleans
    var isDebug = "0";
    if (containerVersion.debugMode) {
        isDebug = "1";
    }
    // Cloud Function Endpoint URL
    const API_PATH = 'https://<YOUR GCP DOMAIN>.cloudfunctions.net/<CLOUD-FUNCTION-PATH>';
    const data = {
        url: API_PATH,
        body: {
            "eventPayload": params,
            "token": "XXXXXXXXX", // secret token without which the cloud function won't do anything
            "attrs": {
                "origin": "gtm",
                "gtmContainerId": containerId,
                "gtmDebugMode": isDebug
            }
        }
    };

    const postHeaders = {'Content-Type': 'application/json'};
    let postBodyData = data.body;

    const postBody = JSON.stringify(postBodyData);
    const now = getTimestamp();
    const twoHoursAgo = now - 1000 * 60 * 60 * 2;

    const stored_uid_ts = uid + "_timestamp"; // name of the file that tells us when this user ID's data was last requested
    // if tpldatastorage does not have a cached file or if this file is older than 2 hours, we initiate the request to pubsub+cloud functions
    if (!templateDataStorage.getItemCopy(uid) || templateDataStorage.getItemCopy(stored_uid_ts) < twoHoursAgo) {
        // fire pubsub request
        sendHttpRequest(data.url, (statusCode, headers, body) => {
            if (statusCode >= 200 && statusCode < 300) {
                log(body);
                setResponseStatus(200);
                setResponseHeader('Content-Type', 'application/json');
                setResponseBody(JSON.stringify(body));
                log('Got Response from Google Cloud Function. Storing in Template Storage Cache and returning to requestor.');
                templateDataStorage.setItemCopy(uid, JSON.stringify(body));
                templateDataStorage.setItemCopy(stored_uid_ts, now);
                returnResponse();
            } else {
                fail("request failed!");
            }
        }, {headers: postHeaders, method: 'POST', timeout: 5000}, postBody); // wait max 5 sec for the response
    } else {
        const cached_data = templateDataStorage.getItemCopy(uid);
        setResponseHeader('Content-Type', 'application/json');
        setResponseBody(cached_data);
        log('Data for User ID ' + uid + ' found in template data cache, returning cached version.');
        log(cached_data);
        returnResponse();
    }
}