Added debounce, fixed error handling for search results, fixed bug in paginated lists

src/app/+search-page/search-service/search.service.ts

@@ -23,7 +23,7 @@ import { DSpaceObject } from '../../core/shared/dspace-object.model';
 import { GenericConstructor } from '../../core/shared/generic-constructor';
 import { HALEndpointService } from '../../core/shared/hal-endpoint.service';
 import {
-  configureRequest,
+  configureRequest, filterSuccessfulResponses,
   getResponseFromEntry,
   getSucceededRemoteData
 } from '../../core/shared/operators';
@@ -104,7 +104,7 @@ export class SearchService implements OnDestroy {
 
     // get search results from response cache
     const sqrObs: Observable<SearchQueryResponse> = requestEntryObs.pipe(
-      getResponseFromEntry(),
+      filterSuccessfulResponses(),
       map((response: SearchSuccessResponse) => response.results)
     );
 

src/app/core/data/paginated-list.ts

@@ -1,5 +1,5 @@
 import { PageInfo } from '../shared/page-info.model';
-import { hasValue } from '../../shared/empty.util';
+import { hasNoValue, hasValue } from '../../shared/empty.util';
 
 export class PaginatedList<T> {
 
@@ -22,6 +22,9 @@ export class PaginatedList<T> {
     if (hasValue(this.pageInfo) && hasValue(this.pageInfo.totalElements)) {
       return this.pageInfo.totalElements;
     }
+    if (hasNoValue(this.page)) {
+      return 0;
+    }
     return this.page.length;
   }
 

src/app/shared/dso-selector/dso-selector/dso-selector.component.spec.ts

@@ -1,4 +1,4 @@
-import { async, ComponentFixture, TestBed } from '@angular/core/testing';
+import { async, ComponentFixture, fakeAsync, TestBed, tick } from '@angular/core/testing';
 import { TranslateModule } from '@ngx-translate/core';
 import { DebugElement, NO_ERRORS_SCHEMA } from '@angular/core';
 import { DSOSelectorComponent } from './dso-selector.component';
@@ -21,7 +21,12 @@ describe('DSOSelectorComponent', () => {
   const type = DSpaceObjectType.ITEM;
   const searchResult = new ItemSearchResult();
   const item = new Item();
-  item.metadata = { 'dc.title': [Object.assign(new MetadataValue(), { value: 'Item title', language: undefined })] };
+  item.metadata = {
+    'dc.title': [Object.assign(new MetadataValue(), {
+      value: 'Item title',
+      language: undefined
+    })]
+  };
   searchResult.dspaceObject = item;
   searchResult.hitHighlights = {};
   const searchService = jasmine.createSpyObj('searchService', {
@@ -46,6 +51,7 @@ describe('DSOSelectorComponent', () => {
     debugElement = fixture.debugElement;
     component.currentDSOId = currentDSOId;
     component.type = type;
+
     fixture.detectChanges();
   });
 
@@ -59,7 +65,9 @@ describe('DSOSelectorComponent', () => {
       dsoType: type,
       pagination: (component as any).defaultPagination
     });
+
     expect(searchService.search).toHaveBeenCalledWith(searchOptions);
   });
 
-});
+})
+;

src/app/shared/dso-selector/dso-selector/dso-selector.component.ts

@@ -1,5 +1,4 @@
 import {
-  AfterViewInit,
   Component,
   ElementRef,
   EventEmitter,
@@ -12,7 +11,7 @@ import {
 import { FormControl } from '@angular/forms';
 
 import { Observable } from 'rxjs';
-import { map, startWith, switchMap, take } from 'rxjs/operators';
+import { debounceTime, startWith, switchMap } from 'rxjs/operators';
 import { SearchService } from '../../../+search-page/search-service/search.service';
 import { PaginatedSearchOptions } from '../../../+search-page/paginated-search-options.model';
 import { DSpaceObjectType } from '../../../core/shared/dspace-object-type.model';
@@ -68,6 +67,11 @@ export class DSOSelectorComponent implements OnInit {
    */
   @ViewChildren('listEntryElement') listElements: QueryList<ElementRef>;
 
+  /**
+   * Time to wait before sending a search request to the server when a user types something
+   */
+  debounceTime = 500;
+
   constructor(private searchService: SearchService) {
   }
 
@@ -79,6 +83,7 @@ export class DSOSelectorComponent implements OnInit {
     this.input.setValue(this.currentDSOId);
     this.listEntries$ = this.input.valueChanges
       .pipe(
+        debounceTime(this.debounceTime),
         startWith(this.currentDSOId),
         switchMap((query) => {
             return this.searchService.search(