decrease the number of unnecessary rerenders by checking whether the relationship types have changed

Author: artlowel

src/app/item-page/edit-item-page/item-relationships/edit-relationship-list/edit-relationship-list.component.ts

@@ -347,15 +347,15 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
                 );
               }),
               take(1)
-            )
+            );
           } else {
             return EMPTY;
           }
         }),
         toArray(),
       ).subscribe({
         complete: () => {
-          this.editItemRelationshipsService.submit(this.item, this.url)
+          this.editItemRelationshipsService.submit(this.item, this.url);
           this.submitModal.emit();
         }
       });

src/app/item-page/edit-item-page/item-relationships/item-relationships.component.ts

@@ -1,14 +1,13 @@
 import { ChangeDetectorRef, Component } from '@angular/core';
-import { Item } from '../../../core/shared/item.model';
+
+
 import {
-  DeleteRelationship,
-  RelationshipIdentifiable,
-} from '../../../core/data/object-updates/object-updates.reducer';
-import { map, switchMap, take, concatMap, toArray, tap } from 'rxjs/operators';
+  map,
+  distinctUntilChanged
+} from 'rxjs/operators';
 import {
-  combineLatest as observableCombineLatest,
   Observable,
-  BehaviorSubject, EMPTY
+  BehaviorSubject
 } from 'rxjs';
 import { followLink } from '../../../shared/utils/follow-link-config.model';
 import { AbstractItemUpdateComponent } from '../abstract-item-update/abstract-item-update.component';
@@ -18,23 +17,17 @@ import { ActivatedRoute, Router } from '@angular/router';
 import { NotificationsService } from '../../../shared/notifications/notifications.service';
 import { TranslateService } from '@ngx-translate/core';
 import { RelationshipDataService } from '../../../core/data/relationship-data.service';
-import { RemoteData } from '../../../core/data/remote-data';
 import { ObjectCacheService } from '../../../core/cache/object-cache.service';
 import { getFirstSucceededRemoteData, getRemoteDataPayload } from '../../../core/shared/operators';
 import { RequestService } from '../../../core/data/request.service';
 import { RelationshipType } from '../../../core/shared/item-relationships/relationship-type.model';
 import { ItemType } from '../../../core/shared/item-relationships/item-type.model';
 import { EntityTypeDataService } from '../../../core/data/entity-type-data.service';
-import { Relationship } from '../../../core/shared/item-relationships/relationship.model';
-import { NoContent } from '../../../core/shared/NoContent.model';
-import { hasValue } from '../../../shared/empty.util';
-import { FieldUpdate } from '../../../core/data/object-updates/field-update.model';
-import { FieldUpdates } from '../../../core/data/object-updates/field-updates.model';
-import { FieldChangeType } from '../../../core/data/object-updates/field-change-type.model';
 import { RelationshipTypeDataService } from '../../../core/data/relationship-type-data.service';
 import { PaginatedList } from '../../../core/data/paginated-list.model';
 import { NgbModal } from '@ng-bootstrap/ng-bootstrap';
 import { EditItemRelationshipsService } from './edit-item-relationships.service';
+import { compareArraysUsingIds } from '../../simple/item-types/shared/item-relationships-utils';
 
 @Component({
   selector: 'ds-item-relationships',
@@ -89,7 +82,8 @@ export class ItemRelationshipsComponent extends AbstractItemUpdateComponent {
     if (label !== undefined) {
       this.relationshipTypes$ = this.relationshipTypeService.searchByEntityType(label, true, true, ...this.getRelationshipTypeFollowLinks())
       .pipe(
-        map((relationshipTypes: PaginatedList<RelationshipType>) => relationshipTypes.page)
+        map((relationshipTypes: PaginatedList<RelationshipType>) => relationshipTypes.page),
+        distinctUntilChanged(compareArraysUsingIds())
       );
 
       this.entityTypeService.getEntityTypeByLabel(label).pipe(