Support inv-by cache dependencies from HAL bodies

src/client.ts

@@ -154,6 +154,10 @@ export default class Client {
   cacheState(state: State) {
 
     this.cache.store(state);
+    for(const invByLink of state.links.getMany('inv-by')) {
+      this.addCacheDependency(resolve(invByLink), state.uri);
+    }
+
     const resource = this.resources.get(state.uri);
     if (resource) {
       // We have a resource for this object, notify it as well.
@@ -175,9 +179,29 @@ export default class Client {
    * expire, if another one expires.
    *
    * A server can populate this list using the `inv-by' link.
+   *
+   * @deprecated This property will go private in a future release.
    */
   public cacheDependencies: Map<string, Set<string>> = new Map();
 
+  /**
+   * Adds a cache dependency between two resources.
+   *
+   * If the 'target' resource ever expires, it will cause 'dependentUri' to
+   * also expire.
+   *
+   * Both argument MUST be absolute urls.
+   */
+  addCacheDependency(targetUri: string, dependentUri: string): void {
+
+    if (this.cacheDependencies.has(targetUri)) {
+      this.cacheDependencies.get(targetUri)!.add(dependentUri);
+    } else {
+      this.cacheDependencies.set(targetUri, new Set([dependentUri]));
+    }
+
+  }
+
   /**
    * Helper function for clearing the cache for a resource.
    *

src/middlewares/cache.ts

@@ -30,21 +30,6 @@ export default function(client: Client): FetchMiddleware {
 
     const response = await next(request);
 
-    // If the response had a Link: rel=inv-by header, it means that when the
-    // target uri's cache expires, the uri of this resource should also
-    // expire.
-    if (response.headers.has('Link')) {
-      for (const httpLink of LinkHeader.parse(response.headers.get('Link')!).rel('inv-by')) {
-        const uri = resolve(request.url, httpLink.uri);
-        if (client.cacheDependencies.has(uri)) {
-          client.cacheDependencies.get(uri)!.add(request.url);
-        } else {
-          client.cacheDependencies.set(uri, new Set([request.url]));
-        }
-      }
-    }
-
-
     if (isSafeMethod(request.method)) {
       return response;
     }

test/unit/client.ts

@@ -152,37 +152,85 @@ describe('Client', () => {
     });
   });
 
-  it('should invalidate dependent resources if they were previously linked with "inv-by"', async () => {
-
-    const client = new Client('https://example.org');
-    client.cache.store(new BaseState({
-      client,
-      uri: 'https://example.org/foo',
-      data: 'hello',
-      headers: new Headers(),
-      links: new Links('http://example.org/foo'),
-    }));
-
-    const request1 = new Request('https://example.org/foo', {
-      method: 'GET',
-    });
+  describe('inv-by links', () => {
 
-    const headers = new Headers();
-    headers.append('Link', '</bar>; rel="inv-by"');
-    client.use( async req => {
-      return new Response('OK', { headers });
-    });
+    it('should invalidate dependent resources if they were previously linked with "inv-by"', async () => {
 
-    await client.fetcher.fetch(request1);
-    expect(client.cache.has('https://example.org/foo')).to.equal(true);
+      const client = new Client('https://example.org');
+      client.cacheState(new BaseState({
+        client,
+        uri: 'https://example.org/foo',
+        data: 'hello',
+        headers: new Headers(),
+        links: new Links('http://example.org/foo'),
+      }));
+
+      const headers = new Headers();
+      headers.append('Link', '</bar>; rel="inv-by"');
+      client.use( async req => {
+        return new Response('OK', { headers });
+      });
+
+      // Get the representation of /foo, which should set up the inv-by link
+      await client.go('https://example.org/foo').refresh();
+
+      expect(client.cache.has('https://example.org/foo')).to.equal(true);
+
+      // Lets invalidate /bar, which should also invalidate /foo
+      const request2 = new Request('https://example.org/bar', {
+        method: 'PUT',
+      });
+      await client.fetcher.fetch(request2);
+
+      expect(client.cache.has('https://example.org/foo')).to.equal(false);
 
-    // Lets invalidate /bar, which should also invalidate /foo
-    const request2 = new Request('https://example.org/bar', {
-      method: 'PUT',
     });
-    await client.fetcher.fetch(request2);
 
-    expect(client.cache.has('https://example.org/foo')).to.equal(false);
+    it('should also work when the inv-by dependency was set up via a link in an embedded HAL document', async() => {
+
+      const embeddedLinks = new Links('https://example.org/parent');
+      embeddedLinks.set('inv-by', '/bar');
+
+      const client = new Client('https://example.org');
+      client.cacheState(new BaseState({
+        client,
+        uri: 'https://example.org/parent',
+        data: 'hello',
+        headers: new Headers(),
+        links: new Links('http://example.org/parent'),
+        embedded: [
+
+          // This is the real resource we're interested in expiring
+          new BaseState({
+            client,
+            uri: 'https://example.org/foo',
+            links: embeddedLinks,
+            headers: new Headers(),
+            data: 'sup',
+          }),
+        ]
+      }));
+
+      const headers = new Headers();
+      headers.append('Link', '</bar>; rel="inv-by"');
+      client.use( async req => {
+        return new Response('OK', { headers });
+      });
+
+      // Get the representation of /foo, which should set up the inv-by link
+      await client.go('https://example.org/foo').refresh();
+
+      expect(client.cache.has('https://example.org/foo')).to.equal(true);
+
+      // Lets invalidate /bar, which should also invalidate /foo
+      const request2 = new Request('https://example.org/bar', {
+        method: 'PUT',
+      });
+      await client.fetcher.fetch(request2);
+
+      expect(client.cache.has('https://example.org/foo')).to.equal(false);
+
+    });
 
   });