Add implementation of getGoogleAnalyticsClientId (#7158)

* Add initial implementation of getGoogleAnalyticsClientId

* Update docs devsite

* Add checkset

* Update changeset description

* Add link to client_id in docstring

* Update gtagWrapper to take variable number of args for potential fallthrough case

* Add API test for getGoogleAnalyticsClientId

* Move API functionality to internal function

* Update docs for devsite

* Removed unused function in test

* Update public api with async keyword

* Remove comment

* Update doc string

* Update grammar of changeset

* Remove console.log

* Update variable name from targetId to measurementId

* Removed check for blank measurementId

* Add ERROR_FACTORY for promise rejection

* Change fieldName from clientId

* Update AnalyticsError.NO_CLIENT_ID message

* Testing adding comment

* remove test comment

* Remove comments

Author: dwyfrequency

.changeset/silent-islands-fix.md

@@ -0,0 +1,6 @@
+---
+'@firebase/analytics': minor
+'firebase': minor
+---
+
+Add method `getGoogleAnalyticsClientId()` to retrieve an unique identifier for a web client. This allows users to log purchase and other events from their backends using Google Analytics 4 Measurement Protocol and to have those events be connected to actions taken on the client within their Firebase web app. `getGoogleAnalyticsClientId()` will simplify this event recording process.

common/api-review/analytics.api.md

@@ -133,6 +133,9 @@ export interface EventParams {
 // @public
 export function getAnalytics(app?: FirebaseApp): Analytics;
 
+// @public
+export function getGoogleAnalyticsClientId(analyticsInstance: Analytics): Promise<string>;
+
 // @public
 export interface GtagConfigParams {
     // (undocumented)

docs-devsite/analytics.md

@@ -20,6 +20,7 @@ Firebase Analytics
 |  [getAnalytics(app)](./analytics.md#getanalytics) | Returns an [Analytics](./analytics.analytics.md#analytics_interface) instance for the given app. |
 |  [initializeAnalytics(app, options)](./analytics.md#initializeanalytics) | Returns an [Analytics](./analytics.analytics.md#analytics_interface) instance for the given app. |
 |  <b>function(analyticsInstance...)</b> |
+|  [getGoogleAnalyticsClientId(analyticsInstance)](./analytics.md#getgoogleanalyticsclientid) | Retrieves a unique Google Analytics identifier for the web client. See [client\_id](https://developers.google.com/analytics/devguides/collection/ga4/reference/config#client_id)<!-- -->. |
 |  [logEvent(analyticsInstance, eventName, eventParams, options)](./analytics.md#logevent) | Sends a Google Analytics event with given <code>eventParams</code>. This method automatically associates this logged event with this Firebase web app instance on this device.<!-- -->List of recommended event parameters can be found in [the GA4 reference documentation](https://developers.google.com/gtagjs/reference/ga4-events)<!-- -->. |
 |  [logEvent(analyticsInstance, eventName, eventParams, options)](./analytics.md#logevent) | Sends a Google Analytics event with given <code>eventParams</code>. This method automatically associates this logged event with this Firebase web app instance on this device.<!-- -->List of recommended event parameters can be found in [the GA4 reference documentation](https://developers.google.com/gtagjs/reference/ga4-events)<!-- -->. |
 |  [logEvent(analyticsInstance, eventName, eventParams, options)](./analytics.md#logevent) | Sends a Google Analytics event with given <code>eventParams</code>. This method automatically associates this logged event with this Firebase web app instance on this device.<!-- -->See [Track Screenviews](https://firebase.google.com/docs/analytics/screenviews)<!-- -->. |
@@ -121,6 +122,26 @@ export declare function initializeAnalytics(app: FirebaseApp, options?: Analytic
 
 [Analytics](./analytics.analytics.md#analytics_interface)
 
+## getGoogleAnalyticsClientId()
+
+Retrieves a unique Google Analytics identifier for the web client. See [client\_id](https://developers.google.com/analytics/devguides/collection/ga4/reference/config#client_id)<!-- -->.
+
+<b>Signature:</b>
+
+```typescript
+export declare function getGoogleAnalyticsClientId(analyticsInstance: Analytics): Promise<string>;
+```
+
+### Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  analyticsInstance | [Analytics](./analytics.analytics.md#analytics_interface) |  |
+
+<b>Returns:</b>
+
+Promise&lt;string&gt;
+
 ## logEvent()
 
 Sends a Google Analytics event with given `eventParams`<!-- -->. This method automatically associates this logged event with this Firebase web app instance on this device.

packages/analytics/src/api.ts

@@ -50,7 +50,8 @@ import {
   setUserProperties as internalSetUserProperties,
   setAnalyticsCollectionEnabled as internalSetAnalyticsCollectionEnabled,
   _setConsentDefaultForInit,
-  _setDefaultEventParametersForInit
+  _setDefaultEventParametersForInit,
+  internalGetGoogleAnalyticsClientId
 } from './functions';
 import { ERROR_FACTORY, AnalyticsError } from './errors';
 
@@ -167,6 +168,24 @@ export function setCurrentScreen(
   ).catch(e => logger.error(e));
 }
 
+/**
+ * Retrieves a unique Google Analytics identifier for the web client.
+ * See {@link https://developers.google.com/analytics/devguides/collection/ga4/reference/config#client_id | client_id}.
+ *
+ * @public
+ *
+ * @param app - The {@link @firebase/app#FirebaseApp} to use.
+ */
+export async function getGoogleAnalyticsClientId(
+  analyticsInstance: Analytics
+): Promise<string> {
+  analyticsInstance = getModularInstance(analyticsInstance);
+  return internalGetGoogleAnalyticsClientId(
+    wrappedGtagFunction,
+    initializationPromisesMap[analyticsInstance.app.options.appId!]
+  );
+}
+
 /**
  * Use gtag `config` command to set `user_id`.
  *

packages/analytics/src/constants.ts

@@ -35,5 +35,6 @@ export const enum GtagCommand {
   EVENT = 'event',
   SET = 'set',
   CONFIG = 'config',
-  CONSENT = 'consent'
+  CONSENT = 'consent',
+  GET = 'get'
 }

packages/analytics/src/errors.ts

@@ -28,6 +28,7 @@ export const enum AnalyticsError {
   CONFIG_FETCH_FAILED = 'config-fetch-failed',
   NO_API_KEY = 'no-api-key',
   NO_APP_ID = 'no-app-id',
+  NO_CLIENT_ID = 'no-client-id',
   INVALID_GTAG_RESOURCE = 'invalid-gtag-resource'
 }
 
@@ -66,6 +67,7 @@ const ERRORS: ErrorMap<AnalyticsError> = {
   [AnalyticsError.NO_APP_ID]:
     'The "appId" field is empty in the local Firebase config. Firebase Analytics requires this field to' +
     'contain a valid app ID.',
+  [AnalyticsError.NO_CLIENT_ID]: 'The "client_id" field is empty.',
   [AnalyticsError.INVALID_GTAG_RESOURCE]:
     'Trusted Types detected an invalid gtag resource: {$gtagURL}.'
 };

packages/analytics/src/functions.test.ts

@@ -27,10 +27,13 @@ import {
   defaultEventParametersForInit,
   _setDefaultEventParametersForInit,
   _setConsentDefaultForInit,
-  defaultConsentSettingsForInit
+  defaultConsentSettingsForInit,
+  internalGetGoogleAnalyticsClientId
 } from './functions';
 import { GtagCommand } from './constants';
 import { ConsentSettings } from './public-types';
+import { Gtag } from './types';
+import { AnalyticsError } from './errors';
 
 const fakeMeasurementId = 'abcd-efgh-ijkl';
 const fakeInitializationPromise = Promise.resolve(fakeMeasurementId);
@@ -238,4 +241,34 @@ describe('FirebaseAnalytics methods', () => {
       ...additionalParams
     });
   });
+  it('internalGetGoogleAnalyticsClientId() rejects when no client_id is available', async () => {
+    await expect(
+      internalGetGoogleAnalyticsClientId(
+        function fakeWrappedGtag(
+          unused1: unknown,
+          unused2: unknown,
+          unused3: unknown,
+          callBackStub: (clientId: string) => {}
+        ): void {
+          callBackStub('');
+        } as Gtag,
+        fakeInitializationPromise
+      )
+    ).to.be.rejectedWith(AnalyticsError.NO_CLIENT_ID);
+  });
+  it('internalGetGoogleAnalyticsClientId() returns client_id when available', async () => {
+    const CLIENT_ID = 'clientId1234';
+    const id = await internalGetGoogleAnalyticsClientId(
+      function fakeWrappedGtag(
+        unused1: unknown,
+        unused2: unknown,
+        unused3: unknown,
+        callBackStub: (clientId: string) => {}
+      ): void {
+        callBackStub(CLIENT_ID);
+      } as Gtag,
+      fakeInitializationPromise
+    );
+    expect(id).to.equal(CLIENT_ID);
+  });
 });

packages/analytics/src/functions.ts

@@ -24,6 +24,7 @@ import {
 } from './public-types';
 import { Gtag } from './types';
 import { GtagCommand } from './constants';
+import { AnalyticsError, ERROR_FACTORY } from './errors';
 
 /**
  * Event parameters to set on 'gtag' during initialization.
@@ -137,6 +138,32 @@ export async function setUserProperties(
   }
 }
 
+/**
+ * Retrieves a unique Google Analytics identifier for the web client.
+ * See {@link https://developers.google.com/analytics/devguides/collection/ga4/reference/config#client_id | client_id}.
+ *
+ * @param gtagFunction Wrapped gtag function that waits for fid to be set before sending an event
+ */
+export async function internalGetGoogleAnalyticsClientId(
+  gtagFunction: Gtag,
+  initializationPromise: Promise<string>
+): Promise<string> {
+  const measurementId = await initializationPromise;
+  return new Promise((resolve, reject) => {
+    gtagFunction(
+      GtagCommand.GET,
+      measurementId,
+      'client_id',
+      (clientId: string) => {
+        if (!clientId) {
+          reject(ERROR_FACTORY.create(AnalyticsError.NO_CLIENT_ID));
+        }
+        resolve(clientId);
+      }
+    );
+  });
+}
+
 /**
  * Set whether collection is enabled for this ID.
  *

packages/analytics/src/helpers.test.ts

@@ -332,6 +332,37 @@ describe('Gtag wrapping functions', () => {
       expect((window['dataLayer'] as DataLayer).length).to.equal(1);
     });
 
+    it('new window.gtag function does not wait when sending "get" calls', async () => {
+      wrapOrCreateGtag(
+        { [fakeAppId]: Promise.resolve(fakeMeasurementId) },
+        fakeDynamicConfigPromises,
+        {},
+        'dataLayer',
+        'gtag'
+      );
+      window['dataLayer'] = [];
+      (window['gtag'] as Gtag)(
+        GtagCommand.GET,
+        fakeMeasurementId,
+        'client_id',
+        clientId => console.log(clientId)
+      );
+      expect((window['dataLayer'] as DataLayer).length).to.equal(1);
+    });
+
+    it('new window.gtag function does not wait when sending an unknown command', async () => {
+      wrapOrCreateGtag(
+        { [fakeAppId]: Promise.resolve(fakeMeasurementId) },
+        fakeDynamicConfigPromises,
+        {},
+        'dataLayer',
+        'gtag'
+      );
+      window['dataLayer'] = [];
+      (window['gtag'] as Gtag)('new-command-from-gtag-team', fakeMeasurementId);
+      expect((window['dataLayer'] as DataLayer).length).to.equal(1);
+    });
+
     it('new window.gtag function waits for initialization promise when sending "config" calls', async () => {
       const initPromise1 = new Deferred<string>();
       wrapOrCreateGtag(

packages/analytics/src/helpers.ts

@@ -277,37 +277,49 @@ function wrapGtag(
    * @param gtagParams Params if event is EVENT/CONFIG.
    */
   async function gtagWrapper(
-    command: 'config' | 'set' | 'event' | 'consent',
-    idOrNameOrParams: string | ControlParams,
-    gtagParams?: GtagConfigOrEventParams | ConsentSettings
+    command: 'config' | 'set' | 'event' | 'consent' | 'get' | string,
+    ...args: unknown[]
   ): Promise<void> {
     try {
       // If event, check that relevant initialization promises have completed.
       if (command === GtagCommand.EVENT) {
+        const [measurementId, gtagParams] = args;
         // If EVENT, second arg must be measurementId.
         await gtagOnEvent(
           gtagCore,
           initializationPromisesMap,
           dynamicConfigPromisesList,
-          idOrNameOrParams as string,
+          measurementId as string,
           gtagParams as GtagConfigOrEventParams
         );
       } else if (command === GtagCommand.CONFIG) {
+        const [measurementId, gtagParams] = args;
         // If CONFIG, second arg must be measurementId.
         await gtagOnConfig(
           gtagCore,
           initializationPromisesMap,
           dynamicConfigPromisesList,
           measurementIdToAppId,
-          idOrNameOrParams as string,
+          measurementId as string,
           gtagParams as GtagConfigOrEventParams
         );
       } else if (command === GtagCommand.CONSENT) {
-        // If CONFIG, second arg must be measurementId.
+        const [gtagParams] = args;
         gtagCore(GtagCommand.CONSENT, 'update', gtagParams as ConsentSettings);
-      } else {
+      } else if (command === GtagCommand.GET) {
+        const [measurementId, fieldName, callback] = args;
+        gtagCore(
+          GtagCommand.GET,
+          measurementId as string,
+          fieldName as string,
+          callback as (...args: unknown[]) => void
+        );
+      } else if (command === GtagCommand.SET) {
+        const [customParams] = args;
         // If SET, second arg must be params.
-        gtagCore(GtagCommand.SET, idOrNameOrParams as CustomParams);
+        gtagCore(GtagCommand.SET, customParams as CustomParams);
+      } else {
+        gtagCore(command, ...args);
       }
     } catch (e) {
       logger.error(e);

packages/analytics/src/types.ts

@@ -73,6 +73,13 @@ export interface Gtag {
     subCommand: 'default' | 'update',
     consentSettings: ConsentSettings
   ): void;
+  (
+    command: 'get',
+    measurementId: string,
+    fieldName: string,
+    callback: (...args: unknown[]) => void
+  ): void;
+  (command: string, ...args: unknown[]): void;
 }
 
 export type DataLayer = IArguments[];