Fix #5336: General system alert visible to users in real time without…

src/app/system-wide-alert/alert-banner/system-wide-alert-banner.component.spec.ts

@@ -7,6 +7,11 @@ import {
   waitForAsync,
 } from '@angular/core/testing';
 import { By } from '@angular/platform-browser';
+import {
+  NavigationEnd,
+  Router,
+} from '@angular/router';
+import { APP_CONFIG } from '@dspace/config/app-config.interface';
 import { SystemWideAlertDataService } from '@dspace/core/data/system-wide-alert-data.service';
 import { NotificationsService } from '@dspace/core/notification-system/notifications.service';
 import { SystemWideAlert } from '@dspace/core/shared/system-wide-alert.model';
@@ -16,11 +21,13 @@ import { createSuccessfulRemoteDataObject$ } from '@dspace/core/utilities/remote
 import { TranslateModule } from '@ngx-translate/core';
 import { utcToZonedTime } from 'date-fns-tz';
 import { getTestScheduler } from 'jasmine-marbles';
+import { of } from 'rxjs';
 import { TestScheduler } from 'rxjs/testing';
 
 import { SystemWideAlertBannerComponent } from './system-wide-alert-banner.component';
 
 
+
 describe('SystemWideAlertBannerComponent', () => {
   let comp: SystemWideAlertBannerComponent;
   let fixture: ComponentFixture<SystemWideAlertBannerComponent>;
@@ -53,6 +60,8 @@ describe('SystemWideAlertBannerComponent', () => {
       providers: [
         { provide: SystemWideAlertDataService, useValue: systemWideAlertDataService },
         { provide: NotificationsService, useValue: new NotificationsServiceStub() },
+        { provide: Router, useValue: { events: of(new NavigationEnd(0, '/test', '/test')) } },
+        { provide: APP_CONFIG, useValue: { systemWideAlert: { refreshIntervalMs: 300000 } } },
       ],
     }).compileComponents();
   }));

src/app/system-wide-alert/alert-banner/system-wide-alert-banner.component.ts

@@ -9,6 +9,14 @@ import {
   OnInit,
   PLATFORM_ID,
 } from '@angular/core';
+import {
+  NavigationEnd,
+  Router,
+} from '@angular/router';
+import {
+  APP_CONFIG,
+  AppConfig,
+} from '@dspace/config/app-config.interface';
 import { PaginatedList } from '@dspace/core/data/paginated-list.model';
 import { SystemWideAlertDataService } from '@dspace/core/data/system-wide-alert-data.service';
 import { NotificationsService } from '@dspace/core/notification-system/notifications.service';
@@ -29,7 +37,9 @@ import {
 import {
   filter,
   map,
+  startWith,
   switchMap,
+  throttleTime,
 } from 'rxjs/operators';
 
 /**
@@ -73,20 +83,29 @@ export class SystemWideAlertBannerComponent implements OnInit, OnDestroy {
 
   constructor(
     @Inject(PLATFORM_ID) protected platformId: any,
+    @Inject(APP_CONFIG) protected appConfig: AppConfig,
     protected systemWideAlertDataService: SystemWideAlertDataService,
     protected notificationsService: NotificationsService,
+    protected router: Router,
   ) {
   }
 
   ngOnInit() {
-    this.subscriptions.push(this.systemWideAlertDataService.searchBy('active').pipe(
-      getAllSucceededRemoteDataPayload(),
-      map((payload: PaginatedList<SystemWideAlert>) => payload.page),
-      filter((page) => isNotEmpty(page)),
-      map((page) => page[0]),
-    ).subscribe((alert: SystemWideAlert) => {
-      this.systemWideAlert$.next(alert);
-    }));
+    this.subscriptions.push(
+      this.router.events.pipe(
+        filter(event => event instanceof NavigationEnd),
+        startWith(null),
+        throttleTime(this.appConfig.systemWideAlert?.refreshIntervalMs ?? 5 * 60 * 1000),
+        switchMap(() =>
+          this.systemWideAlertDataService.searchBy('active', null, false, true),
+        ),
+        getAllSucceededRemoteDataPayload(),
+        map((payload: PaginatedList<SystemWideAlert>) => payload.page),
+        map((page) => isNotEmpty(page) ? page[0] : null),
+      ).subscribe((alert: SystemWideAlert) => {
+        this.systemWideAlert$.next(alert);
+      }),
+    );
 
     this.subscriptions.push(this.systemWideAlert$.pipe(
       switchMap((alert: SystemWideAlert) => {
@@ -100,7 +119,6 @@ export class SystemWideAlertBannerComponent implements OnInit, OnDestroy {
             } else {
               return EMPTY;
             }
-
           }
         }
         // Reset the countDown times to 0 and return EMPTY to prevent unnecessary countdown calculations
@@ -120,7 +138,6 @@ export class SystemWideAlertBannerComponent implements OnInit, OnDestroy {
    */
   private setTimeDifference(countdownTo: string) {
     const date = zonedTimeToUtc(countdownTo, 'UTC');
-
     const timeDifference = date.getTime() - new Date().getTime();
     this.allocateTimeUnits(timeDifference);
   }

src/config/app-config.interface.ts

@@ -77,6 +77,9 @@ interface AppConfig extends Config {
   searchResult: SearchResultConfig;
   addToAnyPlugin: AddToAnyPluginConfig;
   cms: CmsMetadata;
+  systemWideAlert?: {
+    refreshIntervalMs: number;
+  };
 }
 
 /**

src/config/default-app-config.ts

@@ -140,6 +140,13 @@ export class DefaultAppConfig implements AppConfig {
     },
   };
 
+  // System-wide alert settings
+  systemWideAlert = {
+    // How often (in milliseconds) the system-wide alert is refreshed during navigation.
+    // Prevents spamming the endpoint on every route change.
+    refreshIntervalMs: 5 * 60 * 1000, // 5 minutes
+  };
+
   // Form settings
   form: FormConfig = {
     spellCheck: true,