108588: Fixed browse by issue date show loading icon indefinitely when empty

(cherry picked from commit 6f51bd866c)

src/app/browse-by/browse-by-date-page/browse-by-date-page.component.spec.ts

@@ -23,6 +23,7 @@ import { PaginationServiceStub } from '../../shared/testing/pagination-service.s
 import { APP_CONFIG } from '../../../config/app-config.interface';
 import { environment } from '../../../environments/environment';
 import { SortDirection } from '../../core/cache/models/sort-options.model';
+import { cold } from 'jasmine-marbles';
 
 describe('BrowseByDatePageComponent', () => {
   let comp: BrowseByDatePageComponent;
@@ -112,9 +113,13 @@ describe('BrowseByDatePageComponent', () => {
     fixture.detectChanges();
   });
 
-  it('should initialize the list of items', () => {
+  it('should initialize the list of items', (done: DoneFn) => {
+    expect(comp.loading$).toBeObservable(cold('(a|)', {
+      a: false,
+    }));
     comp.items$.subscribe((result) => {
       expect(result.payload.page).toEqual([firstItem]);
+      done();
     });
   });
 

src/app/browse-by/browse-by-date-page/browse-by-date-page.component.ts

@@ -4,7 +4,7 @@ import {
   browseParamsToOptions,
   getBrowseSearchOptions
 } from '../browse-by-metadata-page/browse-by-metadata-page.component';
-import { combineLatest as observableCombineLatest } from 'rxjs';
+import { combineLatest as observableCombineLatest, Observable } from 'rxjs';
 import { hasValue, isNotEmpty } from '../../shared/empty.util';
 import { ActivatedRoute, Params, Router } from '@angular/router';
 import { BrowseService } from '../../core/browse/browse.service';
@@ -85,12 +85,21 @@ export class BrowseByDatePageComponent extends BrowseByMetadataPageComponent {
    * @param scope           The scope under which to fetch the earliest item for
    */
   updateStartsWithOptions(definition: string, metadataKeys: string[], scope?: string) {
-    const firstItemRD = this.browseService.getFirstItemFor(definition, scope, SortDirection.ASC);
-    const lastItemRD = this.browseService.getFirstItemFor(definition, scope, SortDirection.DESC);
+    const firstItemRD$: Observable<RemoteData<Item>> = this.browseService.getFirstItemFor(definition, scope, SortDirection.ASC);
+    const lastItemRD$: Observable<RemoteData<Item>> = this.browseService.getFirstItemFor(definition, scope, SortDirection.DESC);
+    this.loading$ = observableCombineLatest([
+      firstItemRD$,
+      lastItemRD$,
+    ]).pipe(
+      map(([firstItemRD, lastItemRD]: [RemoteData<Item>, RemoteData<Item>]) => firstItemRD.isLoading || lastItemRD.isLoading)
+    );
     this.subs.push(
-      observableCombineLatest([firstItemRD, lastItemRD]).subscribe(([firstItem, lastItem]) => {
-        let lowerLimit: number = this.getLimit(firstItem, metadataKeys, this.appConfig.browseBy.defaultLowerLimit);
-        let upperLimit: number = this.getLimit(lastItem, metadataKeys, new Date().getUTCFullYear());
+      observableCombineLatest([
+        firstItemRD$,
+        lastItemRD$,
+      ]).subscribe(([firstItemRD, lastItemRD]: [RemoteData<Item>, RemoteData<Item>]) => {
+        let lowerLimit: number = this.getLimit(firstItemRD, metadataKeys, this.appConfig.browseBy.defaultLowerLimit);
+        let upperLimit: number = this.getLimit(lastItemRD, metadataKeys, new Date().getUTCFullYear());
         const options: number[] = [];
         const oneYearBreak: number = Math.floor((upperLimit - this.appConfig.browseBy.oneYearLimit) / 5) * 5;
         const fiveYearBreak: number = Math.floor((upperLimit - this.appConfig.browseBy.fiveYearLimit) / 10) * 10;

src/app/browse-by/browse-by-metadata-page/browse-by-metadata-page.component.html

@@ -32,7 +32,7 @@
 
     <section class="comcol-page-browse-section">
     <div class="browse-by-metadata w-100">
-    <ds-themed-browse-by *ngIf="startsWithOptions" class="col-xs-12 w-100"
+    <ds-themed-browse-by *ngIf="!(loading$ | async)" class="col-xs-12 w-100"
       title="{{'browse.title' | translate:
       {
         collection: dsoNameService.getName((parent$ | async)?.payload),
@@ -49,7 +49,7 @@
       (prev)="goPrev()"
       (next)="goNext()">
     </ds-themed-browse-by>
-    <ds-themed-loading *ngIf="!startsWithOptions" message="{{'loading.browse-by-page' | translate}}"></ds-themed-loading>
+    <ds-themed-loading *ngIf="loading$ | async" message="{{'loading.browse-by-page' | translate}}"></ds-themed-loading>
   </div>
   </section>
   <ng-container *ngVar="(parent$ | async) as parent">

src/app/browse-by/browse-by-metadata-page/browse-by-metadata-page.component.spec.ts

@@ -30,6 +30,7 @@ import { PaginationService } from '../../core/pagination/pagination.service';
 import { PaginationComponentOptions } from '../../shared/pagination/pagination-component-options.model';
 import { PaginationServiceStub } from '../../shared/testing/pagination-service.stub';
 import { APP_CONFIG } from '../../../config/app-config.interface';
+import { cold } from 'jasmine-marbles';
 
 describe('BrowseByMetadataPageComponent', () => {
   let comp: BrowseByMetadataPageComponent;
@@ -149,9 +150,13 @@ describe('BrowseByMetadataPageComponent', () => {
       fixture.detectChanges();
     });
 
-    it('should fetch items', () => {
+    it('should fetch items', (done: DoneFn) => {
+      expect(comp.loading$).toBeObservable(cold('(a|)', {
+        a: false,
+      }));
       comp.items$.subscribe((result) => {
         expect(result.payload.page).toEqual(mockItems);
+        done();
       });
     });
 

src/app/browse-by/browse-by-metadata-page/browse-by-metadata-page.component.ts

@@ -1,4 +1,4 @@
-import { combineLatest as observableCombineLatest, Observable, Subscription } from 'rxjs';
+import { combineLatest as observableCombineLatest, Observable, Subscription, of as observableOf } from 'rxjs';
 import { Component, Inject, OnInit, OnDestroy } from '@angular/core';
 import { RemoteData } from '../../core/data/remote-data';
 import { PaginatedList } from '../../core/data/paginated-list.model';
@@ -122,6 +122,11 @@ export class BrowseByMetadataPageComponent implements OnInit, OnDestroy {
    */
   fetchThumbnails: boolean;
 
+  /**
+   * Observable determining if the loading animation needs to be shown
+   */
+  loading$ = observableOf(true);
+
   public constructor(protected route: ActivatedRoute,
                      protected browseService: BrowseService,
                      protected dsoService: DSpaceObjectDataService,
@@ -200,6 +205,9 @@ export class BrowseByMetadataPageComponent implements OnInit, OnDestroy {
    */
   updatePage(searchOptions: BrowseEntrySearchOptions) {
     this.browseEntries$ = this.browseService.getBrowseEntriesFor(searchOptions);
+    this.loading$ = this.browseEntries$.pipe(
+      map((browseEntriesRD: RemoteData<PaginatedList<BrowseEntry>>) => browseEntriesRD.isLoading),
+    );
     this.items$ = undefined;
   }
 
@@ -214,6 +222,9 @@ export class BrowseByMetadataPageComponent implements OnInit, OnDestroy {
    */
   updatePageWithItems(searchOptions: BrowseEntrySearchOptions, value: string, authority: string) {
     this.items$ = this.browseService.getBrowseItemsFor(value, authority, searchOptions);
+    this.loading$ = this.items$.pipe(
+      map((itemsRD: RemoteData<PaginatedList<Item>>) => itemsRD.isLoading),
+    );
   }
 
   /**