add support for paginated properties on dspace objects

src/app/core/cache/builders/remote-data-build.service.spec.ts

+import { RemoteDataBuildService } from './remote-data-build.service';
+import { Item } from '../../shared/item.model';
+import { PaginatedList } from '../../data/paginated-list';
+import { PageInfo } from '../../shared/page-info.model';
+import { RemoteData } from '../../data/remote-data';
+import { Observable } from 'rxjs/Observable';
+
+const pageInfo = new PageInfo();
+const array = [
+  Object.assign(new Item(), {
+    metadata: [
+      {
+        key: 'dc.title',
+        language: 'en_US',
+        value: 'Item nr 1'
+      }]
+  }),
+  Object.assign(new Item(), {
+    metadata: [
+      {
+        key: 'dc.title',
+        language: 'en_US',
+        value: 'Item nr 2'
+      }]
+  })
+];
+const paginatedList = new PaginatedList(pageInfo, array);
+const arrayRD = new RemoteData(false, false, true, undefined, array);
+const paginatedListRD = new RemoteData(false, false, true, undefined, paginatedList);
+
+describe('RemoteDataBuildService', () => {
+  let service: RemoteDataBuildService;
+
+  beforeEach(() => {
+    service = new RemoteDataBuildService(undefined, undefined, undefined);
+  });
+
+  describe('when toPaginatedList is called', () => {
+    let expected: RemoteData<PaginatedList<Item>>;
+
+    beforeEach(() => {
+      expected = paginatedListRD;
+    });
+
+    it('should return the correct remoteData of a paginatedList when the input is a (remoteData of an) array', () => {
+      const result = (service as any).toPaginatedList(Observable.of(arrayRD), pageInfo);
+      result.subscribe((resultRD) => {
+        expect(resultRD).toEqual(expected);
+      });
+    });
+
+    it('should return the correct remoteData of a paginatedList when the input is a (remoteData of a) paginated list', () => {
+      const result = (service as any).toPaginatedList(Observable.of(paginatedListRD), pageInfo);
+      result.subscribe((resultRD) => {
+        expect(resultRD).toEqual(expected);
+      });
+    });
+  });
+});

src/app/core/cache/builders/remote-data-build.service.ts

 import { Injectable } from '@angular/core';
 import { Observable } from 'rxjs/Observable';
-import { distinctUntilChanged, flatMap, map, startWith } from 'rxjs/operators';
+import { distinctUntilChanged, filter, flatMap, map, startWith, switchMap } from 'rxjs/operators';
 import { hasValue, hasValueOperator, isEmpty, isNotEmpty } from '../../../shared/empty.util';
 import { PaginatedList } from '../../data/paginated-list';
 import { RemoteData } from '../../data/remote-data';
@@ -190,7 +190,7 @@ export class RemoteDataBuildService {
         }
 
         if (hasValue(normalized[relationship].page)) {
-          links[relationship] = this.aggregatePaginatedList(result, normalized[relationship].pageInfo);
+          links[relationship] = this.toPaginatedList(result, normalized[relationship].pageInfo);
         } else {
           links[relationship] = result;
         }
@@ -254,8 +254,14 @@ export class RemoteDataBuildService {
       })
   }
 
-  aggregatePaginatedList<T>(input: Observable<RemoteData<T[]>>, pageInfo: PageInfo): Observable<RemoteData<PaginatedList<T>>> {
-    return input.map((rd) => Object.assign(rd, {payload: new PaginatedList(pageInfo, rd.payload)}));
+  private toPaginatedList<T>(input: Observable<RemoteData<T[] | PaginatedList<T>>>, pageInfo: PageInfo): Observable<RemoteData<PaginatedList<T>>> {
+    return input.map((rd: RemoteData<T[] | PaginatedList<T>>) => {
+      if (Array.isArray(rd.payload)) {
+        return Object.assign(rd, { payload: new PaginatedList(pageInfo, rd.payload) })
+      } else {
+        return Object.assign(rd, { payload: new PaginatedList(pageInfo, rd.payload.page) });
+      }
+    });
   }
 
 }

src/app/core/data/base-response-parsing.service.ts

@@ -6,7 +6,6 @@ import { ObjectCacheService } from '../cache/object-cache.service';
 import { GlobalConfig } from '../../../config/global-config.interface';
 import { GenericConstructor } from '../shared/generic-constructor';
 import { PaginatedList } from './paginated-list';
-import { NormalizedObject } from '../cache/models/normalized-object.model';
 import { ResourceType } from '../shared/resource-type';
 import { RESTURLCombiner } from '../url-combiner/rest-url-combiner';
 
@@ -15,7 +14,7 @@ function isObjectLevel(halObj: any) {
 }
 
 function isPaginatedResponse(halObj: any) {
-  return isNotEmpty(halObj.page) && hasValue(halObj._embedded);
+  return hasValue(halObj.page) && hasValue(halObj._embedded);
 }
 
 /* tslint:disable:max-classes-per-file */
@@ -130,7 +129,7 @@ export abstract class BaseResponseParsingService {
   }
 
   processPageInfo(payload: any): PageInfo {
-    if (isNotEmpty(payload.page)) {
+    if (hasValue(payload.page)) {
       const pageObj = Object.assign({}, payload.page, { _links: payload._links });
       const pageInfoObject = new DSpaceRESTv2Serializer(PageInfo).deserialize(pageObj);
       if (pageInfoObject.currentPage >= 0) {

src/app/core/shared/item.model.ts

 import { Observable } from 'rxjs/Observable';
+import { filter, map, startWith, tap } from 'rxjs/operators';
 
 import { DSpaceObject } from './dspace-object.model';
 import { Collection } from './collection.model';

src/app/core/shared/operators.ts

@@ -59,7 +59,7 @@ export const toDSpaceObjectListRD = () =>
     source.pipe(
       map((rd: RemoteData<PaginatedList<SearchResult<T>>>) => {
         const dsoPage: T[] = rd.payload.page.map((searchResult: SearchResult<T>) => searchResult.dspaceObject);
-        const payload = Object.assign(rd.payload, { page: dsoPage }) as PaginatedList<T>;
+        const payload = Object.assign(rd.payload, { page: dsoPage }) as any;
         return Object.assign(rd, {payload: payload});
       })
     );

src/app/shared/loading/loading.component.ts

@@ -3,6 +3,7 @@ import { Component, Input, OnDestroy, OnInit } from '@angular/core';
 import { TranslateService } from '@ngx-translate/core';
 
 import { Subscription } from 'rxjs/Subscription';
+import { hasValue } from '../empty.util';
 
 @Component({
   selector: 'ds-loading',
@@ -28,7 +29,7 @@ export class LoadingComponent implements OnDestroy, OnInit {
   }
 
   ngOnDestroy() {
-    if (this.subscription !== undefined) {
+    if (hasValue(this.subscription)) {
       this.subscription.unsubscribe();
     }
   }