Fix pagination issues

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

@@ -1,6 +1,6 @@
 import {
-  ChangeDetectionStrategy, ChangeDetectorRef, Component, OnDestroy,
-  OnInit
+  ChangeDetectionStrategy, ChangeDetectorRef, Component, DoCheck, OnChanges, OnDestroy,
+  OnInit, SimpleChanges
 } from '@angular/core';
 import { ActivatedRoute, Params } from '@angular/router';
 
@@ -16,6 +16,8 @@ import { Item } from '../core/shared/item.model';
 import { SortOptions, SortDirection } from '../core/cache/models/sort-options.model';
 import { PaginationComponentOptions } from '../shared/pagination/pagination-component-options.model';
 import { hasValue } from '../shared/empty.util';
+import { PageInfo } from '../core/shared/page-info.model';
+import { isUndefined } from 'util';
 
 @Component({
   selector: 'ds-collection-page',
@@ -23,7 +25,7 @@ import { hasValue } from '../shared/empty.util';
   templateUrl: './collection-page.component.html',
   changeDetection: ChangeDetectionStrategy.OnPush
 })
-export class CollectionPageComponent implements OnInit, OnDestroy {
+export class CollectionPageComponent implements OnChanges, OnInit, OnDestroy {
   collectionData: RemoteData<Collection>;
   itemData: RemoteData<Item[]>;
   logoData: RemoteData<Bitstream>;
@@ -31,6 +33,7 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
   sortConfig: SortOptions;
   private subs: Subscription[] = [];
   private collectionId: string;
+  private pageInfoState: PageInfo;
 
   constructor(
     private collectionDataService: CollectionDataService,
@@ -41,6 +44,10 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
 
   }
 
+  ngOnChanges(changes: SimpleChanges) {
+    console.log(changes);
+  }
+
   ngOnInit(): void {
     this.subs.push(this.route.params.map((params: Params) => params.id)
       .subscribe((id: string) => {
@@ -84,13 +91,20 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
   }
 
   updateResults() {
-    this.itemData = undefined;
+    this.itemData = null;
+    this.ref.markForCheck();
     this.itemData = this.itemDataService.findAll({
       scopeID: this.collectionId,
       currentPage: this.config.currentPage,
       elementsPerPage: this.config.pageSize,
       sort: this.sortConfig
     });
-    // this.ref.detectChanges();
+    this.itemData.pageInfo.subscribe((pageInfo) => {
+      if (isUndefined(this.pageInfoState) || this.pageInfoState !== pageInfo) {
+        this.pageInfoState = pageInfo;
+        this.ref.detectChanges();
+      }
+    });
+
   }
 }

src/app/core/cache/response-cache.service.ts

@@ -36,7 +36,6 @@ export class ResponseCacheService {
   get(key: string): Observable<ResponseCacheEntry> {
     return this.store.select<ResponseCacheEntry>('core', 'cache', 'response', key)
       .filter((entry) => this.isValid(entry))
-      .distinctUntilChanged()
   }
 
   /**

src/app/object-list/object-list.component.html

@@ -1,4 +1,5 @@
 <ds-pagination [paginationOptions]="config"
+               [pageInfoState]="pageInfo"
                [collectionSize]="(pageInfo | async)?.totalElements"
                [sortOptions]="sortConfig"
                [hideGear]="hideGear"

src/app/shared/object-list/object-list.component.ts

@@ -5,7 +5,7 @@ import {
   ViewEncapsulation,
   ChangeDetectionStrategy,
   OnInit,
-  Output
+  Output, SimpleChanges, OnChanges, ChangeDetectorRef, DoCheck
 } from '@angular/core';
 
 import { Observable } from 'rxjs/Observable';
@@ -25,7 +25,7 @@ import { SortOptions, SortDirection } from '../../core/cache/models/sort-options
   styleUrls: ['../../object-list/object-list.component.scss'],
   templateUrl: '../../object-list/object-list.component.html'
 })
-export class ObjectListComponent implements OnInit {
+export class ObjectListComponent implements OnChanges, OnInit {
 
   @Input() objects: RemoteData<DSpaceObject[]>;
   @Input() config: PaginationComponentOptions;
@@ -59,10 +59,26 @@ export class ObjectListComponent implements OnInit {
   @Output() sortFieldChange: EventEmitter<string> = new EventEmitter<string>();
   data: any = {};
 
+  ngOnChanges(changes: SimpleChanges) {
+    if (changes.objects && !changes.objects.isFirstChange()) {
+      this.pageInfo = this.objects.pageInfo;
+    }
+  }
+
   ngOnInit(): void {
     this.pageInfo = this.objects.pageInfo;
   }
 
+  /**
+   * @param route
+   *    Route is a singleton service provided by Angular.
+   * @param router
+   *    Router is a singleton service provided by Angular.
+   */
+  constructor(
+    private cdRef: ChangeDetectorRef) {
+  }
+
   onPageChange(event) {
     this.pageChange.emit(event);
   }

src/app/shared/pagination/pagination.component.html

@@ -1,4 +1,5 @@
-<div *ngIf="!hideGear" class="pagination-masked clearfix top">
+<div *ngIf="currentPageState == undefined || currentPageState == currentPage">
+  <div *ngIf="!hideGear" class="pagination-masked clearfix top">
     <div class="row">
       <div class="col pagination-info">
         <span class="align-middle hidden-xs-down">{{ 'pagination.showing.label' | translate }}</span>
@@ -16,11 +17,11 @@
         </div>
       </div>
     </div>
-</div>
+  </div>
 
-<ng-content></ng-content>
+  <ng-content></ng-content>
 
-<div *ngIf="shouldShowBottomPager" class="pagination justify-content-center clearfix bottom">
+  <div *ngIf="shouldShowBottomPager" class="pagination justify-content-center clearfix bottom">
     <ngb-pagination [boundaryLinks]="paginationOptions.boundaryLinks"
                     [collectionSize]="collectionSize"
                     [disabled]="paginationOptions.disabled"
@@ -31,4 +32,5 @@
                     [pageSize]="pageSize"
                     [rotate]="paginationOptions.rotate"
                     [size]="(isXs)?'sm':paginationOptions.size"></ngb-pagination>
+  </div>
 </div>

src/app/shared/pagination/pagination.component.spec.ts

@@ -2,6 +2,7 @@
 import { CommonModule } from '@angular/common';
 
 import {
+  ChangeDetectorRef,
   Component,
   CUSTOM_ELEMENTS_SCHEMA,
   DebugElement
@@ -161,6 +162,7 @@ describe('Pagination component', () => {
         { provide: GLOBAL_CONFIG, useValue: ENV_CONFIG },
         { provide: Router, useValue: routerStub },
         { provide: HostWindowService, useValue: hostWindowServiceStub },
+        ChangeDetectorRef,
         PaginationComponent
       ],
       schemas: [CUSTOM_ELEMENTS_SCHEMA]

src/app/shared/pagination/pagination.component.ts

@@ -1,12 +1,12 @@
-
 import {
-  ChangeDetectionStrategy,
+  ChangeDetectionStrategy, ChangeDetectorRef,
   Component,
   EventEmitter,
   Input,
+  OnChanges,
   OnDestroy,
   OnInit,
-  Output,
+  Output, SimpleChanges,
   ViewEncapsulation
 } from '@angular/core'
 
@@ -22,6 +22,10 @@ import { HostWindowState } from '../host-window.reducer';
 import { PaginationComponentOptions } from './pagination-component-options.model';
 import { SortDirection, SortOptions } from '../../core/cache/models/sort-options.model';
 import { hasValue } from '../empty.util';
+import { PageInfo } from '../../core/shared/page-info.model';
+import { isUndefined } from 'util';
+import { Store } from '@ngrx/store';
+import { ObjectCacheState } from '../../core/cache/object-cache.reducer';
 
 /**
  * The default pagination controls component.
@@ -33,13 +37,18 @@ import { hasValue } from '../empty.util';
   changeDetection: ChangeDetectionStrategy.Default,
   encapsulation: ViewEncapsulation.Emulated
 })
-export class PaginationComponent implements OnDestroy, OnInit {
+export class PaginationComponent implements OnChanges, OnDestroy, OnInit {
 
   /**
    * Number of items in collection.
    */
   @Input() collectionSize: number;
 
+  /**
+   * Page state of a Remote paginated objects.
+   */
+  @Input() pageInfoState: Observable<PageInfo> = undefined;
+
   /**
    * Configuration for the NgbPagination component.
    */
@@ -87,7 +96,12 @@ export class PaginationComponent implements OnDestroy, OnInit {
   /**
    * Current page.
    */
-  public currentPage = 1;
+  public currentPage;
+
+  /**
+   * Current page in the state of a Remote paginated objects.
+   */
+  public currentPageState: number = undefined;
 
   /**
    * Current URL query parameters
@@ -113,12 +127,12 @@ export class PaginationComponent implements OnDestroy, OnInit {
   /**
    * Number of items per page.
    */
-  public pageSize = 10;
+  public pageSize;
 
   /**
    * Declare SortDirection enumeration to use it in the template
    */
-  public sortDirections = SortDirection
+  public sortDirections = SortDirection;
 
   /**
    * A number array that represents options for a context pagination limit.
@@ -154,6 +168,15 @@ export class PaginationComponent implements OnDestroy, OnInit {
     total: null
   };
 
+  ngOnChanges(changes: SimpleChanges) {
+    if (changes.pageInfoState && !changes.pageInfoState.isFirstChange()) {
+      this.subs.push(this.pageInfoState.subscribe((pageInfo) => {
+        /* TODO: this is a temporary fix for the pagination start index (0 or 1) discrepancy between the rest and the frontend respectively */
+        this.currentPageState = pageInfo.currentPage + 1;
+      }));
+    }
+  }
+
   /**
    * Method provided by Angular. Invoked after the constructor.
    */
@@ -161,28 +184,39 @@ export class PaginationComponent implements OnDestroy, OnInit {
     this.subs.push(this.hostWindowService.isXs()
       .subscribe((status: boolean) => {
         this.isXs = status;
+        this.cdRef.markForCheck();
       }));
     this.checkConfig(this.paginationOptions);
+
+    if (this.pageInfoState) {
+       this.subs.push(this.pageInfoState.subscribe((pageInfo) => {
+         /* TODO: this is a temporary fix for the pagination start index (0 or 1) discrepancy between the rest and the frontend respectively */
+         this.currentPageState = pageInfo.currentPage + 1;
+       }));
+    }
+
     this.id = this.paginationOptions.id || null;
-    this.currentPage = this.paginationOptions.currentPage;
-    this.pageSize = this.paginationOptions.pageSize;
     this.pageSizeOptions = this.paginationOptions.pageSizeOptions;
-    this.sortDirection = this.sortOptions.direction;
-    this.sortField = this.sortOptions.field;
     this.subs.push(this.route.queryParams
       .filter((queryParams) => hasValue(queryParams))
       .subscribe((queryParams) => {
         this.currentQueryParams = queryParams;
-        // tslint:disable:triple-equals
-        if (this.id == queryParams.pageId
-          && (this.paginationOptions.currentPage != queryParams.page
-            || this.paginationOptions.pageSize != queryParams.pageSize
-            || this.sortOptions.direction !== queryParams.sortDirection
+        if (this.id === queryParams.pageId
+          && (this.paginationOptions.currentPage !== +queryParams.page
+            || this.paginationOptions.pageSize !== +queryParams.pageSize
+            || this.sortOptions.direction !== +queryParams.sortDirection
             || this.sortOptions.field !== queryParams.sortField)
         ) {
           this.validateParams(queryParams.page, queryParams.pageSize, queryParams.sortDirection, queryParams.sortField);
+        } else if (isUndefined(queryParams.pageId) && !isUndefined(this.currentPage)) {
+          // When moving back from a page with query params to page without them, initialize to the first page
+          this.doPageChange(1);
+        } else {
+          this.currentPage = this.paginationOptions.currentPage;
+          this.pageSize = this.paginationOptions.pageSize;
+          this.sortDirection = this.sortOptions.direction;
+          this.sortField = this.sortOptions.field;
         }
-        // tslint:enable:triple-equals
       }));
     this.setShowingDetail();
   }
@@ -203,6 +237,7 @@ export class PaginationComponent implements OnDestroy, OnInit {
    *    Router is a singleton service provided by Angular.
    */
   constructor(
+    private cdRef: ChangeDetectorRef,
     private route: ActivatedRoute,
     private router: Router,
     public hostWindowService: HostWindowService) {
@@ -317,19 +352,30 @@ export class PaginationComponent implements OnDestroy, OnInit {
           sortDirection: sortDirection,
           sortField: sortField
         }
-      }
-      );
+      });
     } else {
       // (+) converts string to a number
+      if (this.currentPage !== +page) {
         this.currentPage = +page;
-      this.pageSize = +pageSize;
-      this.sortDirection = +sortDirection;
-      this.sortField = sortField;
         this.pageChange.emit(this.currentPage);
+      }
+
+      if (this.pageSize !== +pageSize) {
+        this.pageSize = +pageSize;
         this.pageSizeChange.emit(this.pageSize);
+      }
+
+      if (this.sortDirection !== +sortDirection) {
+        this.sortDirection = +sortDirection;
         this.sortDirectionChange.emit(this.sortDirection);
+      }
+
+      if (this.sortField !== sortField) {
+        this.sortField = sortField;
         this.sortFieldChange.emit(this.sortField);
       }
+      this.cdRef.detectChanges();
+    }
   }
 
   /**