Add the option to regenerate the page view ID with each page view eve…

…nt (close #436)

package.json

@@ -11,6 +11,7 @@
     "sha1": "git://github.com/pvorb/node-sha1.git#v1.0.0"
   },
   "devDependencies": {
+    "js-base64": "2.1.9",
     "JSON": "1.0.0",
     "grunt": "0.4.5",
     "grunt-browserify": "5.0.0",

src/js/snowplow.js

@@ -92,6 +92,7 @@
 			/* Tracker identifier with version */
 			version = 'js-' + '<%= pkg.version %>', // Update banner.js too
 
+			// Initial ID. Can be regenerated by trackPageView
 			pageViewId = uuid.v4(),
 
 			/* Contains four variables that are shared with tracker.js and must be passed by reference */
@@ -127,7 +128,7 @@
 			// Flush all POST queues
 			lodash.forEach(mutSnowplowState.bufferFlushers, function (flusher) {
 				flusher();
-			})
+			});
 
 			/*
 			 * Delay/pause (blocks UI)

src/js/tracker.js

@@ -56,7 +56,8 @@
 	 * @param functionName global function name
 	 * @param namespace The namespace of the tracker object
 	 * @param version The current version of the JavaScript Tracker
-	 * @param pageViewId ID for the current page view, to be attached to all events in the web_page context
+	 * @param pageViewId Initial (can be modified) ID for the current page view, to be attached to 
+	 *        all events in the web_page context.
 	 * @param mutSnowplowState An object containing hasLoaded, registeredOnLoadHandlers, and expireDateTime
 	 * 	      Passed in by reference in case they are altered by snowplow.js
 	 * @param argmap Optional dictionary of configuration options. Supported fields and their default values:
@@ -264,16 +265,15 @@
 			commonContexts = [],
 
 			// Enhanced Ecommerce Contexts to be added on every `trackEnhancedEcommerceAction` call
-			enhancedEcommerceContexts = [];
+			enhancedEcommerceContexts = [],
+
+			// Whether pageViewId should be regenerated after each trackPageView. Affect web_page context
+			preservePageViewId = false;
 
 		if (argmap.hasOwnProperty('discoverRootDomain') && argmap.discoverRootDomain) {
 			configCookieDomain = helpers.findRootDomain();
 		}
 
-		if (autoContexts.webPage) {
-			commonContexts.push(getWebPageContext());
-		}
-
 		if (autoContexts.gaCookies) {
 			commonContexts.push(getGaCookiesContext());
 		}
@@ -738,6 +738,16 @@
 			return ('https:' === documentAlias.location.protocol ? 'https' : 'http') + '://' + rawUrl;
 		}
 
+		/**
+		 * Reset initial `pageViewId` if necessary after successful
+		 * `trackPageView`
+		 */
+		function resetPageViewState() {
+			if (!preservePageViewId) {
+				pageViewId = uuid.v4();
+			}
+		}
+
 		/**
 		 * Add common contexts to every event
 		 * TODO: move this functionality into the core
@@ -748,6 +758,10 @@
 		function addCommonContexts(userContexts) {
 			var combinedContexts = commonContexts.concat(userContexts || []);
 
+			if (autoContexts.webPage) {
+				combinedContexts.push(getWebPageContext());
+			}
+
 			// Add PerformanceTiming Context
 			if (autoContexts.performanceTiming) {
 				var performanceTimingContext = getPerformanceTimingContext();
@@ -1162,6 +1176,8 @@
 				purify(customReferrer || configReferrerUrl),
 				addCommonContexts(finalizeContexts(context, contextCallback)),
 				tstamp);
+
+			resetPageViewState();
 
 			// Send ping (to log that user has stayed on page)
 			var now = new Date();
@@ -2202,6 +2218,13 @@
 			trackError: function (message, filename, lineno, colno, error, contexts) {
 				var enrichedContexts = addCommonContexts(contexts);
 			    errorManager.trackError(message, filename, lineno, colno, error, enrichedContexts);
+			},
+
+			/**
+			 * Stop regenerating `pageViewId` (available from `web_page` context)
+			 */
+			preservePageViewId: function () {
+				preservePageViewId = true
 			}
 		};
 	};

tests/integration/integration.js

@@ -37,8 +37,10 @@ define([
 	'intern/chai!assert',
 	'intern/dojo/node!lodash',
 	'intern/dojo/node!http',
-	'intern/dojo/node!url'
-], function(registerSuite, assert, lodash, http, url) {
+	'intern/dojo/node!url',
+	"intern/dojo/node!js-base64"
+], function(registerSuite, assert, lodash, http, url, jsBase64) {
+	var decodeBase64 = jsBase64.Base64.fromBase64;
 
 	/**
 	 * Expected amount of request for each browser
@@ -198,6 +200,11 @@ define([
 						(event.data.message != null)
 				}
 			}))
+		},
+
+		'Check pageViewId is regenerated for each trackPageView': function () {
+			assert.isTrue(pageViewsHaveDifferentIds());
 		}
+
 	})
 });

tests/pages/integration-template.html

@@ -24,7 +24,10 @@
 		window.snowplow('newTracker', 'cf', subdomain + '.ngrok.io', {
 			encodeBase64: true,
 			appId: 'CFe23a',
-			platform: 'mob'
+			platform: 'mob',
+			contexts: {
+				webPage: true
+			}
 		});
 
 		window.snowplow('setUserId', 'Malcolm');
@@ -37,6 +40,9 @@
 			}
 		]);
 
+		// This should have different pageViewId in web_page context
+		window.snowplow('trackPageView');
+
 		window.snowplow('trackStructEvent', 'Mixes', 'Play', 'MRC/fabric-0503-mix', '', '0.0');
 		window.snowplow('trackUnstructEvent', {
 			schema: 'iglu:com.acme_company/viewed_product/jsonschema/5-0-0',