feat(driver): store and set Magento cache ID header (#2743)

libs/driver/magento/src/graphql/cache-header/cache-header-apollo-link.spec.ts

@@ -0,0 +1,90 @@
+import { TestBed } from '@angular/core/testing';
+import {
+  ApolloLink,
+  gql,
+  NextLink,
+  Observable,
+  Operation,
+} from '@apollo/client/core';
+import { Apollo } from 'apollo-angular';
+import {
+  ApolloTestingController,
+  ApolloTestingModule,
+} from 'apollo-angular/testing';
+
+import {
+  DaffMagentoCacheHeaderApolloLinkGenerator,
+  MAGENTO_CUSTOMER_CACHE_ID_HEADER,
+} from './cache-header-apollo-link';
+
+describe('@daffodil/driver/magento | DaffMagentoCacheHeaderApolloLinkGenerator', () => {
+  let service: DaffMagentoCacheHeaderApolloLinkGenerator;
+  let operation: Operation;
+  let apollo: Apollo;
+  let controller: ApolloTestingController;
+  let link: ApolloLink;
+  let linkSpy: jasmine.Spy<NextLink>;
+  let cacheId: string;
+  const query = gql`{ Operation(test: string) { name }}`;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      imports: [
+        ApolloTestingModule,
+      ],
+    });
+
+    controller = TestBed.inject(ApolloTestingController);
+    apollo = TestBed.inject(Apollo);
+    service = TestBed.inject(DaffMagentoCacheHeaderApolloLinkGenerator);
+
+    link = service.getLink();
+    linkSpy = jasmine.createSpy();
+    linkSpy.and.returnValue(Observable.of());
+    cacheId = 'cacheId';
+  });
+
+  describe('getLink', () => {
+    it('should not set the cache header when it was not included with a previous response', () => {
+      apollo.query({ query }).subscribe();
+      operation = controller.expectOne(query).operation;
+      link.request(operation, linkSpy);
+
+      expect(operation.getContext().headers?.[MAGENTO_CUSTOMER_CACHE_ID_HEADER]).toBeFalsy();
+    });
+
+    it('should set the cache header when it was included with a previous response', () => {
+      apollo.query({ query }).subscribe();
+      operation = controller.expectOne(query).operation;
+      operation.setContext({
+        headers: {
+          [MAGENTO_CUSTOMER_CACHE_ID_HEADER]: cacheId,
+        },
+      });
+      link.request(operation, linkSpy);
+
+      expect(operation.getContext().headers?.[MAGENTO_CUSTOMER_CACHE_ID_HEADER]).toEqual(cacheId);
+    });
+
+    it('should set the cache header to the new value when the cache ID changes', () => {
+      const newCacheId = 'newCacheId';
+      apollo.query({ query }).subscribe();
+      operation = controller.expectOne(query).operation;
+      operation.setContext({
+        headers: {
+          [MAGENTO_CUSTOMER_CACHE_ID_HEADER]: cacheId,
+        },
+      });
+      link.request(operation, linkSpy);
+
+      operation.setContext({
+        headers: {
+          [MAGENTO_CUSTOMER_CACHE_ID_HEADER]: newCacheId,
+        },
+      });
+      link.request(operation, linkSpy);
+
+      expect(operation.getContext().headers?.[MAGENTO_CUSTOMER_CACHE_ID_HEADER]).toEqual(newCacheId);
+    });
+  });
+});

libs/driver/magento/src/graphql/cache-header/cache-header-apollo-link.ts

@@ -0,0 +1,40 @@
+import { Injectable } from '@angular/core';
+import { ApolloLink } from '@apollo/client/core';
+
+import { DaffApolloLinkGenerator } from '@daffodil/core/graphql';
+
+export const MAGENTO_CUSTOMER_CACHE_ID_HEADER = 'X-Magento-Cache-Id';
+
+/**
+ * Stores and sets the Magento cache ID header.
+ * This will set the `X-Magento-Cache-Id` header from the most recent value encountered
+ * on a response, if there was a response with that header set.
+ *
+ * @inheritdoc
+ */
+@Injectable({
+  providedIn: 'root',
+})
+export class DaffMagentoCacheHeaderApolloLinkGenerator implements DaffApolloLinkGenerator {
+  private _cacheHeader?: string;
+
+  getLink(): ApolloLink {
+    return new ApolloLink((operation, forward) => {
+      if (this._cacheHeader) {
+        operation.setContext({
+          headers: {
+            ...operation.getContext().headers,
+            [MAGENTO_CUSTOMER_CACHE_ID_HEADER]: this._cacheHeader,
+          },
+        });
+      }
+      return forward(operation).map((response) => {
+        const { headers } = operation.getContext().response;
+        if (headers.get(MAGENTO_CUSTOMER_CACHE_ID_HEADER)) {
+          this._cacheHeader = headers.get(MAGENTO_CUSTOMER_CACHE_ID_HEADER);
+        }
+        return response;
+      });
+    });
+  }
+}

libs/driver/magento/src/graphql/public_api.ts

@@ -2,3 +2,4 @@ export { DaffMagentoApolloCacheableOperationsLinkGenerator } from './cacheable-o
 export * from './cacheable-operations/cacheable-operations-token';
 export * from './type-policies';
 export * from './cache.service';
+export * from './cache-header/cache-header-apollo-link';