fix(statistics): clear statistics table pagination params on destroy

Statistics pagination is URL-driven with queryParamsHandling: 'merge', so a page/rpp selection made on one scope's statistics page persisted in the URL when navigating to another scope. Clear the table's own params on destroy, like other paginated components do.

Verified on the seeded local instance that ds-pagination already renders and pages correctly at community, collection and item level via the shared StatisticsTableComponent (DSpace#726); no further frontend change is needed for lower-level pagination.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: jr-rk

src/app/statistics-page/collection-statistics-page/collection-statistics-page.component.spec.ts

@@ -83,7 +83,7 @@ describe('CollectionStatisticsPageComponent', () => {
         { provide: DSpaceObjectDataService, useValue: {} },
         { provide: DSONameService, useValue: nameService },
         { provide: AuthService, useValue: authService },
-        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }) } },
+        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }), clearPagination: () => undefined } },
       ],
     })
       .compileComponents();

src/app/statistics-page/community-statistics-page/community-statistics-page.component.spec.ts

@@ -83,7 +83,7 @@ describe('CommunityStatisticsPageComponent', () => {
         { provide: DSpaceObjectDataService, useValue: {} },
         { provide: DSONameService, useValue: nameService },
         { provide: AuthService, useValue: authService },
-        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }) } },
+        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }), clearPagination: () => undefined } },
       ],
     })
       .compileComponents();

src/app/statistics-page/item-statistics-page/item-statistics-page.component.spec.ts

@@ -83,7 +83,7 @@ describe('ItemStatisticsPageComponent', () => {
         { provide: DSpaceObjectDataService, useValue: {} },
         { provide: DSONameService, useValue: nameService },
         { provide: AuthService, useValue: authService },
-        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }) } },
+        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }), clearPagination: () => undefined } },
       ],
     })
       .compileComponents();

src/app/statistics-page/site-statistics-page/site-statistics-page.component.spec.ts

@@ -84,7 +84,7 @@ describe('SiteStatisticsPageComponent', () => {
         { provide: DSONameService, useValue: nameService },
         { provide: SiteDataService, useValue: siteService },
         { provide: AuthService, useValue: authService },
-        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }) } },
+        { provide: PaginationService, useValue: { getCurrentPagination: () => observableOf({ currentPage: 1, pageSize: 10 }), clearPagination: () => undefined } },
       ],
     })
       .compileComponents();

src/app/statistics-page/statistics-table/statistics-table.component.spec.ts

@@ -47,6 +47,7 @@ describe('StatisticsTableComponent', () => {
 
   const paginationService = {
     getCurrentPagination: (_id: string, _options: PaginationComponentOptions) => currentPagination$.asObservable(),
+    clearPagination: (_id: string) => undefined,
   };
 
   const setPage = (currentPage: number, pageSize = 10) => {
@@ -221,4 +222,25 @@ describe('StatisticsTableComponent', () => {
       expect(de.query(By.css(`td.item_${numberOfPoints - 1}-views-data`))).toBeTruthy();
     });
   });
+
+  describe('on destroy', () => {
+
+    it('should clear its own pagination params so they do not leak to the next scope', () => {
+      component.report = Object.assign(new UsageReport(), {
+        id: 'uuid_TotalVisits',
+        points: [],
+      });
+      component.ngOnInit();
+      const spy = spyOn(paginationService, 'clearPagination');
+
+      fixture.destroy();
+
+      expect(spy).toHaveBeenCalledWith('stats-uuid_TotalVisits');
+    });
+
+    it('should not throw when destroyed before initialisation', () => {
+      const uninitialised = TestBed.createComponent(StatisticsTableComponent).componentInstance;
+      expect(() => uninitialised.ngOnDestroy()).not.toThrow();
+    });
+  });
 });

src/app/statistics-page/statistics-table/statistics-table.component.ts

@@ -6,6 +6,7 @@ import {
 import {
   Component,
   Input,
+  OnDestroy,
   OnInit,
 } from '@angular/core';
 import {
@@ -43,7 +44,7 @@ import { PaginationComponentOptions } from '../../shared/pagination/pagination-c
   standalone: true,
   imports: [NgIf, NgFor, AsyncPipe, TranslateModule, PaginationComponent],
 })
-export class StatisticsTableComponent implements OnInit {
+export class StatisticsTableComponent implements OnInit, OnDestroy {
 
   /**
    * The usage report to display a statistics table for
@@ -110,6 +111,14 @@ export class StatisticsTableComponent implements OnInit {
     );
   }
 
+  ngOnDestroy() {
+    // Drop this table's page/rpp query params so they don't leak (via queryParamsHandling: 'merge') to the next
+    // scope's statistics page. Guarded in case the component is destroyed before ngOnInit ran.
+    if (this.paginationOptions) {
+      this.paginationService.clearPagination(this.paginationOptions.id);
+    }
+  }
+
   /**
    * Get the row label to display for a statistics point.
    * @param point the statistics point to get the label for