fixed an issue where the pagination would always open on the first page if you went to the URL of a different page

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

@@ -1,4 +1,7 @@
-import { ChangeDetectorRef, Component, OnDestroy, OnInit } from '@angular/core';
+import {
+  ChangeDetectionStrategy, ChangeDetectorRef, Component, OnDestroy,
+  OnInit
+} from '@angular/core';
 import { ActivatedRoute, Params } from '@angular/router';
 
 import { Collection } from "../core/shared/collection.model";
@@ -11,11 +14,13 @@ 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 { Observable } from "rxjs/Observable";
+import { hasValue } from "../shared/empty.util";
 
 @Component({
   selector: 'ds-collection-page',
   styleUrls: ['./collection-page.component.css'],
   templateUrl: './collection-page.component.html',
+  changeDetection: ChangeDetectionStrategy.OnPush
 })
 export class CollectionPageComponent implements OnInit, OnDestroy {
   collectionData: RemoteData<Collection>;
@@ -45,7 +50,7 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
 
         this.config = new PaginationComponentOptions();
         this.config.id = "collection-browse";
-        this.config.pageSizeOptions = [ 5, 10, 20, 40, 60, 80, 100 ];
+        this.config.pageSizeOptions = [ 4 ];
         this.config.pageSize = 4;
         this.sortConfig =  new SortOptions();
 
@@ -55,7 +60,9 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
   }
 
   ngOnDestroy(): void {
-    this.subs.forEach(sub => sub.unsubscribe());
+    this.subs
+      .filter(sub => hasValue(sub))
+      .forEach(sub => sub.unsubscribe());
   }
 
   universalInit() {
@@ -89,6 +96,6 @@ export class CollectionPageComponent implements OnInit, OnDestroy {
       elementsPerPage: this.config.pageSize,
       sort: this.sortConfig
     });
-    this.ref.detectChanges();
+    // this.ref.detectChanges();
   }
 }

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

@@ -6,6 +6,7 @@ import { Bitstream } from "../core/shared/bitstream.model";
 import { RemoteData } from "../core/data/remote-data";
 import { CommunityDataService } from "../core/data/community-data.service";
 import { Subscription } from "rxjs/Subscription";
+import { hasValue } from "../shared/empty.util";
 
 @Component({
   selector: 'ds-community-page',
@@ -33,7 +34,9 @@ export class CommunityPageComponent implements OnInit, OnDestroy {
   }
 
   ngOnDestroy(): void {
-     this.subs.forEach(sub => sub.unsubscribe());
+     this.subs
+       .filter(sub => hasValue(sub))
+       .forEach(sub => sub.unsubscribe());
   }
 
   universalInit() {

src/app/home/top-level-community-list/top-level-community-list.component.ts

@@ -1,4 +1,4 @@
-import { Component, OnInit, ChangeDetectorRef } from '@angular/core';
+import { Component, OnInit, ChangeDetectorRef, ChangeDetectionStrategy } from '@angular/core';
 import { RemoteData } from "../../core/data/remote-data";
 import { CommunityDataService } from "../../core/data/community-data.service";
 import { Community } from "../../core/shared/community.model";
@@ -8,7 +8,8 @@ import { SortOptions, SortDirection } from "../../core/cache/models/sort-options
 @Component({
   selector: 'ds-top-level-community-list',
   styleUrls: ['./top-level-community-list.component.css'],
-  templateUrl: './top-level-community-list.component.html'
+  templateUrl: './top-level-community-list.component.html',
+  changeDetection: ChangeDetectionStrategy.OnPush
 })
 export class TopLevelCommunityListComponent implements OnInit {
   topLevelCommunities: RemoteData<Community[]>;
@@ -29,7 +30,7 @@ export class TopLevelCommunityListComponent implements OnInit {
   ngOnInit(): void {
     this.config = new PaginationComponentOptions();
     this.config.id = "top-level-pagination";
-    this.config.pageSizeOptions = [ 5, 10, 20, 40, 60, 80, 100 ];
+    this.config.pageSizeOptions = [ 4 ];
     this.config.pageSize = 4;
     this.sortConfig =  new SortOptions();
 
@@ -59,6 +60,6 @@ export class TopLevelCommunityListComponent implements OnInit {
   updateResults() {
     this.topLevelCommunities = undefined;
     this.topLevelCommunities = this.cds.findAll({ currentPage: this.config.currentPage, elementsPerPage: this.config.pageSize, sort: this.sortConfig });
-    this.ref.detectChanges();
+    // this.ref.detectChanges();
   }
 }

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

@@ -9,6 +9,7 @@ import {
     ViewEncapsulation
 } from '@angular/core'
 import { ActivatedRoute, Router } from '@angular/router';
+import { Subscription } from "rxjs/Subscription";
 import { isNumeric } from "rxjs/util/isNumeric";
 import 'rxjs/add/operator/switchMap';
 import { Observable } from "rxjs";
@@ -139,13 +140,13 @@ export class PaginationComponent implements OnDestroy, OnInit {
      */
     public paginationControls;
 
+  /**
+   * Array to track all subscriptions and unsubscribe them onDestroy
+   * @type {Array}
+   */
+  private subs: Subscription[] = [];
 
-    /**
-     * Subscriber to observable.
-     */
-    private routeSubscription: any;
-
-    /**
+  /**
      * An object that represents pagination details of the current viewed page
      */
     public showingDetail: any = {
@@ -153,19 +154,14 @@ export class PaginationComponent implements OnDestroy, OnInit {
         total: null
     };
 
-    /**
-     * Subscriber to observable.
-     */
-    private stateSubscription: any;
-
     /**
      * Method provided by Angular. Invoked after the constructor.
      */
     ngOnInit() {
-        this.stateSubscription = this.hostWindowService.isXs()
+        this.subs.push(this.hostWindowService.isXs()
             .subscribe((status: boolean) => {
                 this.isXs = status;
-            });
+            }));
         this.checkConfig(this.paginationOptions);
         this.id = this.paginationOptions.id || null;
         this.currentPage = this.paginationOptions.currentPage;
@@ -173,7 +169,7 @@ export class PaginationComponent implements OnDestroy, OnInit {
         this.pageSizeOptions = this.paginationOptions.pageSizeOptions;
         this.sortDirection = this.sortOptions.direction;
         this.sortField = this.sortOptions.field;
-        this.routeSubscription = this.route.queryParams
+        this.subs.push(this.route.queryParams
             .filter(queryParams => hasValue(queryParams))
             .subscribe(queryParams => {
                 this.currentQueryParams = queryParams;
@@ -185,7 +181,7 @@ export class PaginationComponent implements OnDestroy, OnInit {
                 ) {
                     this.validateParams(queryParams['page'], queryParams['pageSize'], queryParams['sortDirection'], queryParams['sortField']);
                 }
-            });
+            }));
         this.setShowingDetail();
     }
 
@@ -193,8 +189,9 @@ export class PaginationComponent implements OnDestroy, OnInit {
      * Method provided by Angular. Invoked when the instance is destroyed.
      */
     ngOnDestroy() {
-        this.stateSubscription.unsubscribe();
-        this.routeSubscription.unsubscribe();
+      this.subs
+        .filter(sub => hasValue(sub))
+        .forEach(sub => sub.unsubscribe());
     }
 
     /**