Fix of edge case state handling

Author: danielmurrmann

libs/ngrx-hateoas/src/lib/store-features/with-hypermedia-resource.spec.ts

@@ -376,6 +376,36 @@ describe('withHypermediaResource', () => {
         httpTestingController.verify();
     });
 
+    it('resets state when url signal changes to null after being loaded', (done: DoneFn) => {
+        const resourceFirst: TestModel = {
+            numProp: 2,
+            objProp: { stringProp: 'first response' }
+        };
+
+        const urlSignal = signal<string | null>('api/test-model');
+        store.loadTestModelFromUrl(urlSignal);
+
+        TestBed.flushEffects();
+
+        httpTestingController.expectOne('api/test-model').flush(resourceFirst);
+
+        setTimeout(() => {
+            expect(store.testModelState.isLoaded()).toBeTrue();
+            expect(store.testModel.objProp.stringProp()).toBe('first response');
+
+            urlSignal.set(null);
+            TestBed.flushEffects();
+
+            expect(store.testModelState.url()).toBe('');
+            expect(store.testModelState.isLoaded()).toBeFalse();
+            expect(store.testModelState.isLoading()).toBeFalse();
+            expect(store.testModel()).toBe(initialTestModel);
+
+            httpTestingController.verify();
+            done();
+        }, 0);
+    });
+
     it('loads the resource reactively from a url signal and reloads when signal changes', (done: DoneFn) => {
         const resourceFirst: TestModel = {
             numProp: 2,

libs/ngrx-hateoas/src/lib/store-features/with-linked-hypermedia-resource.spec.ts

@@ -230,4 +230,50 @@ describe('withLinkedHypermediaResource', () => {
         httpTestingController.verify();
     });
 
+    it('resets state when link disappears from root resource after being loaded', async () => {
+        const rootModelFromUrl: RootModel = {
+            apiName: 'loaded model',
+            _links: {
+                testModel: { href: '/api/test-model' }
+            }
+        };
+
+        const testModelFromLink: TestModel = {
+            name: 'from link'
+        };
+
+        const loadRootModel = store.loadRootModelFromUrl('/api/root-model');
+
+        httpTestingController.expectOne('/api/root-model').flush(rootModelFromUrl);
+        httpTestingController.verify();
+
+        await loadRootModel;
+        await firstValueFrom(timer(0));
+
+        httpTestingController.expectOne('/api/test-model').flush(testModelFromLink);
+        httpTestingController.verify();
+
+        await firstValueFrom(timer(0));
+
+        expect(store.testModelState.isLoaded()).toBeTrue();
+        expect(store.testModelState.isAvailable()).toBeTrue();
+        expect(store.testModel.name()).toBe('from link');
+
+        // Reload root model without the link
+        const reloadRootModel = store.reloadRootModel();
+
+        httpTestingController.expectOne('/api/root-model').flush({ apiName: 'loaded model', _links: {} } satisfies RootModel);
+        httpTestingController.verify();
+
+        await reloadRootModel;
+        await firstValueFrom(timer(0));
+
+        expect(store.testModelState.isLoaded()).toBeFalse();
+        expect(store.testModelState.isAvailable()).toBeFalse();
+        expect(store.testModelState.isLoading()).toBeFalse();
+        expect(store.testModel()).toBe(initialTestModel);
+
+        httpTestingController.verify();
+    });
+
 });

libs/ngrx-hateoas/src/lib/store-features/with-linked-hypermedia-resource.ts

@@ -153,6 +153,13 @@ export function withLinkedHypermediaResource<ResourceName extends string, TResou
                     pipe(
                         filter(resource => resource !== undefined),
                         map(resource => hateoasService.getLink(resource, linkMetaName)?.href),
+                        tap(href => {
+                            if (!isValidHref(href)) {
+                                patchState(store,
+                                    updateData(dataKey, initialValue),
+                                    updateState(stateKey, { url: '', isLoading: false, isLoaded: false, isAvailable: false }));
+                            }
+                        }),
                         filter(href => isValidHref(href)),
                         map(href => href!),
                         filter(href => getState(store, stateKey).url !== href),