Add function setDefaultEventParameters() to set data that will be logged on every analytics SDK event

.changeset/silly-panthers-mix.md

@@ -0,0 +1,5 @@
+---
+'@firebase/analytics': minor
+---
+
+Add function `setDefaultEventParameters()` to set data that will be logged on every Analytics SDK event

common/api-review/analytics.api.md

@@ -391,6 +391,9 @@ export function setAnalyticsCollectionEnabled(analyticsInstance: Analytics, enab
 // @public @deprecated
 export function setCurrentScreen(analyticsInstance: Analytics, screenName: string, options?: AnalyticsCallOptions): void;
 
+// @public
+export function setDefaultEventParameters(customParams: CustomParams): void;
+
 // @public
 export function settings(options: SettingsOptions): void;
 

packages/analytics/src/api.test.ts

@@ -19,15 +19,22 @@ import { expect } from 'chai';
 import { SinonStub, stub } from 'sinon';
 import '../testing/setup';
 import { getFullApp } from '../testing/get-fake-firebase-services';
-import { getAnalytics, initializeAnalytics } from './api';
+import {
+  getAnalytics,
+  initializeAnalytics,
+  setDefaultEventParameters
+} from './api';
 import { FirebaseApp, deleteApp } from '@firebase/app';
 import { AnalyticsError } from './errors';
 import * as init from './initialize-analytics';
 const fakeAppParams = { appId: 'abcdefgh12345:23405', apiKey: 'AAbbCCdd12345' };
+import * as factory from './factory';
+import { defaultEventParametersForInit } from './functions';
 
 describe('FirebaseAnalytics API tests', () => {
   let initStub: SinonStub = stub();
   let app: FirebaseApp;
+  const wrappedGtag: SinonStub = stub();
 
   beforeEach(() => {
     initStub = stub(init, '_initializeAnalytics').resolves(
@@ -94,4 +101,26 @@ describe('FirebaseAnalytics API tests', () => {
     const analyticsInstance = initializeAnalytics(app);
     expect(getAnalytics(app)).to.equal(analyticsInstance);
   });
+  it('setDefaultEventParameters() updates defaultEventParametersForInit if gtag does not exist ', () => {
+    const eventParametersForInit = {
+      'github_user': 'dwyfrequency',
+      'company': 'google'
+    };
+    app = getFullApp(fakeAppParams);
+    setDefaultEventParameters(eventParametersForInit);
+    expect(defaultEventParametersForInit).to.deep.equal(eventParametersForInit);
+  });
+  it('setDefaultEventParameters() calls gtag set if wrappedGtagFunction exists', () => {
+    const eventParametersForInit = {
+      'github_user': 'dwyfrequency',
+      'company': 'google'
+    };
+    stub(factory, 'wrappedGtagFunction').get(() => wrappedGtag);
+    app = getFullApp(fakeAppParams);
+    setDefaultEventParameters(eventParametersForInit);
+    expect(wrappedGtag).to.have.been.calledWithExactly(
+      'set',
+      eventParametersForInit
+    );
+  });
 });

packages/analytics/src/api.ts

@@ -35,7 +35,7 @@ import {
   getModularInstance,
   deepEqual
 } from '@firebase/util';
-import { ANALYTICS_TYPE } from './constants';
+import { ANALYTICS_TYPE, GtagCommand } from './constants';
 import {
   AnalyticsService,
   initializationPromisesMap,
@@ -47,7 +47,8 @@ import {
   setCurrentScreen as internalSetCurrentScreen,
   setUserId as internalSetUserId,
   setUserProperties as internalSetUserProperties,
-  setAnalyticsCollectionEnabled as internalSetAnalyticsCollectionEnabled
+  setAnalyticsCollectionEnabled as internalSetAnalyticsCollectionEnabled,
+  _setDefaultEventParametersForInit
 } from './functions';
 import { ERROR_FACTORY, AnalyticsError } from './errors';
 
@@ -224,6 +225,23 @@ export function setAnalyticsCollectionEnabled(
     enabled
   ).catch(e => logger.error(e));
 }
+
+/**
+ * Adds data that will be set on every event logged from the SDK, including automatic ones.
+ * With gtag's "set" command, the values passed persist on the current page and are passed with
+ * all subsequent events.
+ * @public
+ * @param customParams Any custom params the user may pass to gtag.js.
+ */
+export function setDefaultEventParameters(customParams: CustomParams): void {
+  // Check if reference to existing gtag function on window object exists
+  if (wrappedGtagFunction) {
+    wrappedGtagFunction(GtagCommand.SET, customParams);
+  } else {
+    _setDefaultEventParametersForInit(customParams);
+  }
+}
+
 /**
  * Sends a Google Analytics event with given `eventParams`. This method
  * automatically associates this logged event with this Firebase web

packages/analytics/src/functions.test.ts

@@ -23,7 +23,9 @@ import {
   logEvent,
   setUserId,
   setUserProperties,
-  setAnalyticsCollectionEnabled
+  setAnalyticsCollectionEnabled,
+  defaultEventParametersForInit,
+  _setDefaultEventParametersForInit
 } from './functions';
 import { GtagCommand } from './constants';
 
@@ -170,4 +172,24 @@ describe('FirebaseAnalytics methods', () => {
     expect(window[`ga-disable-${fakeMeasurementId}`]).to.be.true;
     delete window[`ga-disable-${fakeMeasurementId}`];
   });
+  it('_setDefaultEventParametersForInit() stores individual params correctly', async () => {
+    const eventParametersForInit = {
+      'github_user': 'dwyfrequency',
+      'company': 'google'
+    };
+    _setDefaultEventParametersForInit(eventParametersForInit);
+    expect(defaultEventParametersForInit).to.deep.equal(eventParametersForInit);
+  });
+  it('_setDefaultEventParametersForInit() replaces previous params with new params', async () => {
+    const eventParametersForInit = {
+      'github_user': 'dwyfrequency',
+      'company': 'google'
+    };
+    const additionalParams = { 'food': 'sushi' };
+    _setDefaultEventParametersForInit(eventParametersForInit);
+    _setDefaultEventParametersForInit(additionalParams);
+    expect(defaultEventParametersForInit).to.deep.equal({
+      ...additionalParams
+    });
+  });
 });

packages/analytics/src/functions.ts

@@ -23,6 +23,12 @@ import {
 } from './public-types';
 import { Gtag } from './types';
 import { GtagCommand } from './constants';
+
+/**
+ * Event parameters to set on 'gtag' during initialization.
+ */
+export let defaultEventParametersForInit: CustomParams | undefined;
+
 /**
  * Logs an analytics event through the Firebase SDK.
  *
@@ -142,3 +148,15 @@ export async function setAnalyticsCollectionEnabled(
   const measurementId = await initializationPromise;
   window[`ga-disable-${measurementId}`] = !enabled;
 }
+
+/**
+ * Sets the variable `defaultEventParametersForInit` for use in the initialization of
+ * analytics.
+ *
+ * @param customParams Any custom params the user may pass to gtag.js.
+ */
+export function _setDefaultEventParametersForInit(
+  customParams?: CustomParams
+): void {
+  defaultEventParametersForInit = customParams;
+}

packages/analytics/src/initialize-analytics.test.ts

@@ -29,6 +29,8 @@ import { FirebaseApp } from '@firebase/app';
 import { Deferred } from '@firebase/util';
 import { _FirebaseInstallationsInternal } from '@firebase/installations';
 import { removeGtagScript } from '../testing/gtag-script-util';
+import { setDefaultEventParameters } from './api';
+import { defaultEventParametersForInit } from './functions';
 
 const fakeMeasurementId = 'abcd-efgh-ijkl';
 const fakeFid = 'fid-1234-zyxw';
@@ -97,6 +99,25 @@ describe('initializeAnalytics()', () => {
       'send_page_view': false
     });
   });
+  it('calls gtag set if there are default event parameters', async () => {
+    stubFetch();
+    const eventParametersForInit = {
+      'github_user': 'dwyfrequency',
+      'company': 'google'
+    };
+    setDefaultEventParameters(eventParametersForInit);
+    await _initializeAnalytics(
+      app,
+      dynamicPromisesList,
+      measurementIdToAppId,
+      fakeInstallations,
+      gtagStub,
+      'dataLayer'
+    );
+    expect(gtagStub).to.be.calledWith(GtagCommand.SET, eventParametersForInit);
+    // defaultEventParametersForInit is reset after initialization.
+    expect(defaultEventParametersForInit).to.equal(undefined);
+  });
   it('puts dynamic fetch promise into dynamic promises list', async () => {
     stubFetch();
     await _initializeAnalytics(

packages/analytics/src/initialize-analytics.ts

@@ -28,6 +28,10 @@ import {
 import { ERROR_FACTORY, AnalyticsError } from './errors';
 import { findGtagScriptOnPage, insertScriptTag } from './helpers';
 import { AnalyticsSettings } from './public-types';
+import {
+  defaultEventParametersForInit,
+  _setDefaultEventParametersForInit
+} from './functions';
 
 async function validateIndexedDB(): Promise<boolean> {
   if (!isIndexedDBAvailable()) {
@@ -140,5 +144,12 @@ export async function _initializeAnalytics(
   // Note: This will trigger a page_view event unless 'send_page_view' is set to false in
   // `configProperties`.
   gtagCore(GtagCommand.CONFIG, dynamicConfig.measurementId, configProperties);
+
+  // Detects if there is data that will be set on every event logged from the SDK.
+  if (defaultEventParametersForInit) {
+    gtagCore(GtagCommand.SET, defaultEventParametersForInit);
+    _setDefaultEventParametersForInit(undefined);
+  }
+
   return dynamicConfig.measurementId;
 }