Cache redesign part 1, and add support for alternative links

src/app/community-list-page/community-list-service.ts

@@ -2,7 +2,7 @@ import { Injectable } from '@angular/core';
 import { createSelector, Store } from '@ngrx/store';
 import { combineLatest as observableCombineLatest } from 'rxjs/internal/observable/combineLatest';
 import { Observable, of as observableOf } from 'rxjs';
-import { map, switchMap } from 'rxjs/operators';
+import { map, switchMap, filter } from 'rxjs/operators';
 import { AppState } from '../app.reducer';
 import { CommunityDataService } from '../core/data/community-data.service';
 import { FindListOptions } from '../core/data/request.models';
@@ -11,12 +11,13 @@ import { Collection } from '../core/shared/collection.model';
 import { PageInfo } from '../core/shared/page-info.model';
 import { hasValue, isNotEmpty } from '../shared/empty.util';
 import { RemoteData } from '../core/data/remote-data';
-import { PaginatedList } from '../core/data/paginated-list';
+import { PaginatedList, buildPaginatedList } from '../core/data/paginated-list.model';
 import { CollectionDataService } from '../core/data/collection-data.service';
 import { CommunityListSaveAction } from './community-list.actions';
 import { CommunityListState } from './community-list.reducer';
 import { getCommunityPageRoute } from '../+community-page/community-page-routing-paths';
 import { getCollectionPageRoute } from '../+collection-page/collection-page-routing-paths';
+import { getFirstSucceededRemoteData, getFirstCompletedRemoteData } from '../core/shared/operators';
 
 /**
  * Each node in the tree is represented by a flatNode which contains info about the node itself and its position and
@@ -46,7 +47,8 @@ export class ShowMoreFlatNode {
 // Helper method to combine an flatten an array of observables of flatNode arrays
 export const combineAndFlatten = (obsList: Array<Observable<FlatNode[]>>): Observable<FlatNode[]> =>
   observableCombineLatest(...obsList).pipe(
-    map((matrix: any[][]) => [].concat(...matrix))
+    map((matrix: any[][]) => [].concat(...matrix)),
+    filter((arr: any[]) => arr.every((e) => hasValue(e))),
   );
 
 /**
@@ -144,10 +146,13 @@ export class CommunityListService {
         if (coms && coms.length > 0) {
           newPageInfo = Object.assign({}, coms[0].pageInfo, { currentPage })
         }
-        return new PaginatedList(newPageInfo, newPage);
+        return buildPaginatedList(newPageInfo, newPage);
       })
     );
-    return topComs$.pipe(switchMap((topComs: PaginatedList<Community>) => this.transformListOfCommunities(topComs, 0, null, expandedNodes)));
+    return topComs$.pipe(
+      switchMap((topComs: PaginatedList<Community>) => this.transformListOfCommunities(topComs, 0, null, expandedNodes)),
+      // distinctUntilChanged((a: FlatNode[], b: FlatNode[]) => a.length === b.length)
+    );
   };
 
   /**
@@ -162,6 +167,7 @@ export class CommunityListService {
         direction: options.sort.direction
       }
     }).pipe(
+      getFirstSucceededRemoteData(),
       map((results) => results.payload),
     );
   }
@@ -227,11 +233,12 @@ export class CommunityListService {
           currentPage: i
         })
           .pipe(
+            getFirstCompletedRemoteData(),
             switchMap((rd: RemoteData<PaginatedList<Community>>) => {
               if (hasValue(rd) && hasValue(rd.payload)) {
                 return this.transformListOfCommunities(rd.payload, level + 1, communityFlatNode, expandedNodes);
               } else {
-                return [];
+                return observableOf([]);
               }
             })
           );
@@ -249,6 +256,7 @@ export class CommunityListService {
           currentPage: i
         })
           .pipe(
+            getFirstCompletedRemoteData(),
             map((rd: RemoteData<PaginatedList<Collection>>) => {
               if (hasValue(rd) && hasValue(rd.payload)) {
                 let nodes = rd.payload.page