fix issue where a submit emitted from the edit relationship modal wouldn't arrive in the edit relationships component

src/app/app.component.ts

@@ -1,4 +1,4 @@
-import { distinctUntilChanged, take, withLatestFrom } from 'rxjs/operators';
+import { distinctUntilChanged, take, withLatestFrom, delay } from 'rxjs/operators';
 import { DOCUMENT, isPlatformBrowser } from '@angular/common';
 import {
   AfterViewInit,
@@ -114,7 +114,10 @@ export class AppComponent implements OnInit, AfterViewInit {
   }
 
   ngAfterViewInit() {
-    this.router.events.subscribe((event) => {
+    this.router.events.pipe(
+      // delay(0) to prevent "Expression has changed after it was checked" errors
+      delay(0)
+    ).subscribe((event) => {
       if (event instanceof NavigationStart) {
         distinctNext(this.isRouteLoading$, true);
       } else if (

src/app/core/data/object-updates/object-updates.reducer.ts

@@ -58,6 +58,8 @@ export interface VirtualMetadataSource {
 
 export interface RelationshipIdentifiable extends Identifiable {
   nameVariant?: string;
+  originalItem: Item;
+  originalIsLeft: boolean
   relatedItem: Item;
   relationship: Relationship;
   type: RelationshipType;

src/app/core/data/relationship-data.service.ts

@@ -309,7 +309,13 @@ export class RelationshipDataService extends IdentifiableDataService<Relationshi
     } else {
       findListOptions.searchParams = searchParams;
     }
-    return this.searchBy('byLabel', findListOptions, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow);
+    const result$ = this.searchBy('byLabel', findListOptions, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow);
+
+    // add this result as a dependency of the item, meaning that if the item is invalided, this
+    // result will be as well
+    this.addDependency(result$, item.self);
+
+    return result$;
   }
 
   /**

src/app/item-page/edit-item-page/item-relationships/edit-item-relationships.service.spec.ts

@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { EditItemRelationshipsService } from './edit-item-relationships.service';
+
+describe('EditItemRelationshipsService', () => {
+  let service: EditItemRelationshipsService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(EditItemRelationshipsService);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+});

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

@@ -0,0 +1,186 @@
+import { Injectable } from '@angular/core';
+import { take, map, switchMap, concatMap, toArray } from 'rxjs/operators';
+import { FieldUpdates } from '../../../core/data/object-updates/field-updates.model';
+import { FieldUpdate } from '../../../core/data/object-updates/field-update.model';
+import { hasValue } from '../../../shared/empty.util';
+import { FieldChangeType } from '../../../core/data/object-updates/field-change-type.model';
+import {
+  DeleteRelationship,
+  RelationshipIdentifiable
+} from '../../../core/data/object-updates/object-updates.reducer';
+import { RemoteData } from '../../../core/data/remote-data';
+import { Relationship } from '../../../core/shared/item-relationships/relationship.model';
+import { EMPTY, Observable } from 'rxjs';
+import { ObjectUpdatesService } from '../../../core/data/object-updates/object-updates.service';
+import { ItemDataService } from '../../../core/data/item-data.service';
+import { Item } from '../../../core/shared/item.model';
+import { NoContent } from '../../../core/shared/NoContent.model';
+import { NotificationsService } from '../../../shared/notifications/notifications.service';
+import { NgbModal } from '@ng-bootstrap/ng-bootstrap';
+import { RelationshipDataService } from '../../../core/data/relationship-data.service';
+import { EntityTypeDataService } from '../../../core/data/entity-type-data.service';
+import { TranslateService } from '@ngx-translate/core';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class EditItemRelationshipsService {
+  public notificationsPrefix = 'static-pages.form.notification';
+
+  constructor(
+    public itemService: ItemDataService,
+    public objectUpdatesService: ObjectUpdatesService,
+    public notificationsService: NotificationsService,
+    protected modalService: NgbModal,
+    public relationshipService: RelationshipDataService,
+    public entityTypeService: EntityTypeDataService,
+    public translateService: TranslateService,
+  ) { }
+
+
+  /**
+   * Resolve the currently selected related items back to relationships and send a delete request for each of the relationships found
+   * Make sure the lists are refreshed afterwards and notifications are sent for success and errors
+   */
+  public submit(item: Item, url: string): void {
+    this.objectUpdatesService.getFieldUpdates(url, [], true).pipe(
+      map((fieldUpdates: FieldUpdates) =>
+        Object.values(fieldUpdates)
+          .filter((fieldUpdate: FieldUpdate) => hasValue(fieldUpdate))
+          .filter((fieldUpdate: FieldUpdate) => fieldUpdate.changeType === FieldChangeType.ADD || fieldUpdate.changeType === FieldChangeType.REMOVE)
+      ),
+      take(1),
+      // emit each update in the array separately
+      switchMap((updates) => updates),
+      // process each update one by one, while waiting for the previous to finish
+      concatMap((update: FieldUpdate) => {
+        if (update.changeType === FieldChangeType.REMOVE) {
+          return this.deleteRelationship(update.field as DeleteRelationship).pipe(take(1));
+        } else if (update.changeType === FieldChangeType.ADD) {
+          return this.addRelationship(update.field as RelationshipIdentifiable).pipe(
+            take(1),
+            switchMap((relationshipRD: RemoteData<Relationship>) => {
+              if (relationshipRD.hasSucceeded) {
+                // Set the newly related item to stale, so its relationships will update to include
+                // the new one. Only set the current item to stale at the very end so we only do it
+                // once
+                const { leftItem, rightItem } = relationshipRD.payload._links;
+                if (leftItem.href === item.self) {
+                  return this.itemService.invalidateByHref(rightItem.href).pipe(
+                    // when it's invalidated, emit the original relationshipRD for use in the pipe below
+                    map(() => relationshipRD)
+                  );
+                } else {
+                  return this.itemService.invalidateByHref(leftItem.href).pipe(
+                    // when it's invalidated, emit the original relationshipRD for use in the pipe below
+                    map(() => relationshipRD)
+                  );
+                }
+              } else {
+                return [relationshipRD];
+              }
+            })
+          );
+        } else {
+          return EMPTY;
+        }
+      }),
+      toArray(),
+      switchMap((responses) => {
+        // once all relationships are made and all related items have been invalidated, invalidate
+        // the current item
+        return this.itemService.invalidateByHref(item.self).pipe(
+          map(() => responses)
+        );
+      })
+    ).subscribe((responses) => {
+      if (responses.length > 0) {
+        this.initializeOriginalFields(item, url);
+        this.displayNotifications(responses);
+        this.modalService.dismissAll();
+      }
+    });
+  }
+
+  /**
+   * Sends all initial values of this item to the object updates service
+   */
+  public initializeOriginalFields(item: Item, url: string) {
+    return this.relationshipService.getRelatedItems(item).pipe(
+      take(1),
+    ).subscribe((items: Item[]) => {
+      this.objectUpdatesService.initialize(url, items, item.lastModified);
+    });
+  }
+
+  deleteRelationship(deleteRelationship: DeleteRelationship): Observable<RemoteData<NoContent>> {
+    let copyVirtualMetadata: string;
+    if (deleteRelationship.keepLeftVirtualMetadata && deleteRelationship.keepRightVirtualMetadata) {
+      copyVirtualMetadata = 'all';
+    } else if (deleteRelationship.keepLeftVirtualMetadata) {
+      copyVirtualMetadata = 'left';
+    } else if (deleteRelationship.keepRightVirtualMetadata) {
+      copyVirtualMetadata = 'right';
+    } else {
+      copyVirtualMetadata = 'none';
+    }
+
+    return this.relationshipService.deleteRelationship(deleteRelationship.uuid, copyVirtualMetadata, false);
+  }
+
+  addRelationship(addRelationship: RelationshipIdentifiable): Observable<RemoteData<Relationship>> {
+    let leftItem: Item;
+    let rightItem: Item;
+    let leftwardValue: string;
+    let rightwardValue: string;
+    if (addRelationship.originalIsLeft) {
+      leftItem = addRelationship.originalItem;
+      rightItem = addRelationship.relatedItem;
+      leftwardValue = null;
+      rightwardValue = addRelationship.nameVariant;
+    } else {
+      leftItem = addRelationship.relatedItem;
+      rightItem = addRelationship.originalItem;
+      leftwardValue = addRelationship.nameVariant;
+      rightwardValue = null;
+    }
+    return this.relationshipService.addRelationship(addRelationship.type.id, leftItem, rightItem, leftwardValue, rightwardValue, false);
+  }
+
+  /**
+   * Display notifications
+   * - Error notification for each failed response with their message
+   * - Success notification in case there's at least one successful response
+   * @param responses
+   */
+  displayNotifications(responses: RemoteData<NoContent>[]) {
+    const failedResponses = responses.filter((response: RemoteData<NoContent>) => response.hasFailed);
+    const successfulResponses = responses.filter((response: RemoteData<NoContent>) => response.hasSucceeded);
+
+    failedResponses.forEach((response: RemoteData<NoContent>) => {
+      this.notificationsService.error(this.getNotificationTitle('failed'), response.errorMessage);
+    });
+    if (successfulResponses.length > 0) {
+      this.notificationsService.success(this.getNotificationTitle('saved'), this.getNotificationContent('saved'));
+    }
+  }
+
+
+
+  /**
+   * Get translated notification title
+   * @param key
+   */
+  getNotificationTitle(key: string) {
+    return this.translateService.instant(this.notificationsPrefix + key + '.title');
+  }
+
+  /**
+   * Get translated notification content
+   * @param key
+   */
+  getNotificationContent(key: string) {
+    return this.translateService.instant(this.notificationsPrefix + key + '.content');
+
+  }
+}

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

@@ -5,6 +5,7 @@ import { ObjectUpdatesService } from '../../../../core/data/object-updates/objec
 import {
   BehaviorSubject,
   combineLatest as observableCombineLatest,
+  EMPTY,
   from as observableFrom,
   Observable,
   Subscription
@@ -14,10 +15,22 @@ import {
 } from '../../../../core/data/object-updates/object-updates.reducer';
 import { RelationshipDataService } from '../../../../core/data/relationship-data.service';
 import { Item } from '../../../../core/shared/item.model';
-import { defaultIfEmpty, map, mergeMap, startWith, switchMap, take, tap, toArray } from 'rxjs/operators';
+import {
+  defaultIfEmpty,
+  map,
+  mergeMap,
+  startWith,
+  switchMap,
+  take,
+  tap,
+  toArray,
+  concatMap
+} from 'rxjs/operators';
 import { hasNoValue, hasValue, hasValueOperator } from '../../../../shared/empty.util';
 import { Relationship } from '../../../../core/shared/item-relationships/relationship.model';
-import { RelationshipType } from '../../../../core/shared/item-relationships/relationship-type.model';
+import {
+  RelationshipType
+} from '../../../../core/shared/item-relationships/relationship-type.model';
 import {
   getAllSucceededRemoteData,
   getFirstSucceededRemoteData,
@@ -25,15 +38,23 @@ import {
   getRemoteDataPayload,
 } from '../../../../core/shared/operators';
 import { ItemType } from '../../../../core/shared/item-relationships/item-type.model';
-import { DsDynamicLookupRelationModalComponent } from '../../../../shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component';
-import { RelationshipOptions } from '../../../../shared/form/builder/models/relationship-options.model';
-import { SelectableListService } from '../../../../shared/object-list/selectable-list/selectable-list.service';
+import {
+  DsDynamicLookupRelationModalComponent
+} from '../../../../shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component';
+import {
+  RelationshipOptions
+} from '../../../../shared/form/builder/models/relationship-options.model';
+import {
+  SelectableListService
+} from '../../../../shared/object-list/selectable-list/selectable-list.service';
 import { SearchResult } from '../../../../shared/search/models/search-result.model';
 import { FollowLinkConfig } from '../../../../shared/utils/follow-link-config.model';
 import { PaginatedList } from '../../../../core/data/paginated-list.model';
 import { RemoteData } from '../../../../core/data/remote-data';
 import { Collection } from '../../../../core/shared/collection.model';
-import { PaginationComponentOptions } from '../../../../shared/pagination/pagination-component-options.model';
+import {
+  PaginationComponentOptions
+} from '../../../../shared/pagination/pagination-component-options.model';
 import { PaginationService } from '../../../../core/pagination/pagination.service';
 import { RelationshipTypeDataService } from '../../../../core/data/relationship-type-data.service';
 import { FieldUpdate } from '../../../../core/data/object-updates/field-update.model';
@@ -41,6 +62,7 @@ import { FieldUpdates } from '../../../../core/data/object-updates/field-updates
 import { FieldChangeType } from '../../../../core/data/object-updates/field-change-type.model';
 import { APP_CONFIG, AppConfig } from '../../../../../config/app-config.interface';
 import { itemLinksToFollow } from '../../../../shared/utils/relation-query.utils';
+import { EditItemRelationshipsService } from '../edit-item-relationships.service';
 
 @Component({
   selector: 'ds-edit-relationship-list',
@@ -90,7 +112,7 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
    * Observable that emits true if {@link itemType} is on the left-hand side of {@link relationshipType},
    * false if it is on the right-hand side and undefined in the rare case that it is on neither side.
    */
-  private currentItemIsLeftItem$: Observable<boolean>;
+  private currentItemIsLeftItem$: BehaviorSubject<boolean> = new BehaviorSubject(undefined);
 
   private relatedEntityType$: Observable<ItemType>;
 
@@ -153,6 +175,7 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
     protected modalService: NgbModal,
     protected paginationService: PaginationService,
     protected selectableListService: SelectableListService,
+    protected editItemRelationshipsService: EditItemRelationshipsService,
     @Inject(APP_CONFIG) protected appConfig: AppConfig
   ) {
     this.fetchThumbnail = this.appConfig.browseBy.showThumbnails;
@@ -211,7 +234,6 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
    * Open the dynamic lookup modal to search for items to add as relationships
    */
   openLookup() {
-
     this.modalRef = this.modalService.open(DsDynamicLookupRelationModalComponent, {
       size: 'lg'
     });
@@ -277,51 +299,59 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
 
 
     modalComp.submitEv = () => {
-
-      const subscriptions = [];
-
-      modalComp.toAdd.forEach((searchResult: SearchResult<Item>) => {
-        const relatedItem = searchResult.indexableObject;
-        subscriptions.push(this.relationshipService.getNameVariant(this.listId, relatedItem.uuid).pipe(
-          map((nameVariant) => {
-          const update = {
-            uuid: this.relationshipType.id + '-' + searchResult.indexableObject.uuid,
-            nameVariant,
-            type: this.relationshipType,
-            relatedItem,
-          } as RelationshipIdentifiable;
-          this.objectUpdatesService.saveAddFieldUpdate(this.url, update);
-          return update;
-        })
-        ));
-      });
-
-      modalComp.toRemove.forEach( (searchResult) => {
-        subscriptions.push(this.relationshipService.getNameVariant(this.listId, searchResult.indexableObjectuuid).pipe(
-          switchMap((nameVariant) => {
-            return this.getRelationFromId(searchResult.indexableObject).pipe(
-              map( (relationship: Relationship) => {
+      modalComp.isPending = true;
+      const isLeft = this.currentItemIsLeftItem$.getValue();
+      const addOperations = modalComp.toAdd.map((searchResult: any) => ({ type: 'add', searchResult }));
+      const removeOperations = modalComp.toRemove.map((searchResult: any) => ({ type: 'remove', searchResult }));
+      observableFrom([...addOperations, ...removeOperations]).pipe(
+        concatMap(({ type, searchResult }: { type: string, searchResult: any }) => {
+          if (type === 'add') {
+            const relatedItem = searchResult.indexableObject;
+            return this.relationshipService.getNameVariant(this.listId, relatedItem.uuid).pipe(
+              map((nameVariant) => {
                 const update = {
-                  uuid: relationship.id,
+                  uuid: this.relationshipType.id + '-' + searchResult.indexableObject.uuid,
                   nameVariant,
                   type: this.relationshipType,
-                  relationship,
+                  originalIsLeft: isLeft,
+                  originalItem: this.item,
+                  relatedItem,
                 } as RelationshipIdentifiable;
-                this.objectUpdatesService.saveRemoveFieldUpdate(this.url,update);
+                this.objectUpdatesService.saveAddFieldUpdate(this.url, update);
                 return update;
-              })
+              }),
+              take(1)
             );
-          })
-        ));
-      });
-
-      observableCombineLatest(subscriptions).subscribe( (res) => {
-        // Wait until the states changes since there are multiple items
-        setTimeout( () => {
+          } else if (type === 'remove') {
+            return this.relationshipService.getNameVariant(this.listId, searchResult.indexableObjectuuid).pipe(
+              switchMap((nameVariant) => {
+                return this.getRelationFromId(searchResult.indexableObject).pipe(
+                  map( (relationship: Relationship) => {
+                    const update = {
+                      uuid: relationship.id,
+                      nameVariant,
+                      type: this.relationshipType,
+                      originalIsLeft: isLeft,
+                      originalItem: this.item,
+                      relationship,
+                    } as RelationshipIdentifiable;
+                    this.objectUpdatesService.saveRemoveFieldUpdate(this.url,update);
+                    return update;
+                  })
+                );
+              }),
+              take(1)
+            )
+          } else {
+            return EMPTY;
+          }
+        }),
+        toArray(),
+      ).subscribe({
+        complete: () => {
+          this.editItemRelationshipsService.submit(this.item, this.url)
           this.submit.emit();
-        },1000);
-
-        modalComp.isPending = true;
+        }
       });
     };
 
@@ -355,27 +385,12 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
   }
 
   getRelationFromId(relatedItem) {
-    return this.currentItemIsLeftItem$.pipe(
-      take(1),
-      switchMap( isLeft => {
-        let apiCall;
-        if (isLeft) {
-          apiCall = this.relationshipService.searchByItemsAndType( this.relationshipType.id, this.item.uuid, this.relationshipType.leftwardType ,[relatedItem.id] ).pipe(
-                      getFirstSucceededRemoteData(),
-                      getRemoteDataPayload(),
-                    );
-        } else {
-          apiCall = this.relationshipService.searchByItemsAndType( this.relationshipType.id, this.item.uuid, this.relationshipType.rightwardType ,[relatedItem.id] ).pipe(
-                      getFirstSucceededRemoteData(),
-                      getRemoteDataPayload(),
-                    );
-        }
-
-        return apiCall.pipe(
-          map( (res: PaginatedList<Relationship>) => res.page[0])
-        );
-      }
-    ));
+    const relationshipLabel = this.currentItemIsLeftItem$.getValue() ? this.relationshipType.leftwardType : this.relationshipType.rightwardType;
+    return this.relationshipService.searchByItemsAndType( this.relationshipType.id, this.item.uuid, relationshipLabel ,[relatedItem.id] ).pipe(
+      getFirstSucceededRemoteData(),
+      getRemoteDataPayload(),
+      map( (res: PaginatedList<Relationship>) => res.page[0])
+    );
   }
 
 
@@ -440,7 +455,6 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
   }
 
   ngOnInit(): void {
-
     // store the left and right type of the relationship in a single observable
     this.relationshipLeftAndRightType$ = observableCombineLatest([
       this.relationshipType.leftType,
@@ -461,7 +475,7 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
       (relatedEntityType) => this.listId = `edit-relationship-${this.itemType.id}-${relatedEntityType.id}`
     );
 
-    this.currentItemIsLeftItem$ = this.relationshipLeftAndRightType$.pipe(
+    this.subs.push(this.relationshipLeftAndRightType$.pipe(
       map(([leftType, rightType]: [ItemType, ItemType]) => {
         if (leftType.id === this.itemType.id) {
           return true;
@@ -475,7 +489,9 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
         console.warn(`The item ${this.item.uuid} is not on the right or the left side of relationship type ${this.relationshipType.uuid}`);
         return undefined;
       })
-    );
+    ).subscribe((nextValue: boolean) => {
+      this.currentItemIsLeftItem$.next(nextValue);
+    }));
 
 
     // initialize the pagination options
@@ -500,19 +516,20 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
         currentPagination$,
         this.currentItemIsLeftItem$,
       ]).pipe(
-        switchMap(([currentPagination, currentItemIsLeftItem]: [PaginationComponentOptions, boolean]) =>
+        switchMap(([currentPagination, currentItemIsLeftItem]: [PaginationComponentOptions, boolean]) => {
           // get the relationships for the current item, relationshiptype and page
-          this.relationshipService.getItemRelationshipsByLabel(
+          return this.relationshipService.getItemRelationshipsByLabel(
             this.item,
             currentItemIsLeftItem ? this.relationshipType.leftwardType : this.relationshipType.rightwardType,
             {
               elementsPerPage: currentPagination.pageSize,
               currentPage: currentPagination.currentPage
             },
-            false,
+            true,
             true,
             ...linksToFollow
-          )),
+          );
+        }),
       ).subscribe((rd: RemoteData<PaginatedList<Relationship>>) => {
         this.relationshipsRd$.next(rd);
       })
@@ -548,6 +565,8 @@ export class EditRelationshipListComponent implements OnInit, OnDestroy {
               uuid: relationship.id,
               type: this.relationshipType,
               relationship,
+              originalIsLeft: isLeftItem,
+              originalItem: this.item,
               nameVariant,
             } as RelationshipIdentifiable;
           }),

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

@@ -108,10 +108,10 @@ export class EditRelationshipComponent implements OnChanges {
    */
   remove(): void {
     this.closeVirtualMetadataModal();
-    observableCombineLatest(
+    observableCombineLatest([
       this.leftItem$,
       this.rightItem$,
-    ).pipe(
+    ]).pipe(
       map((items: Item[]) =>
         items.map((item) => this.objectUpdatesService
           .isSelectedVirtualMetadata(this.url, this.relationship.id, item.uuid))
@@ -127,9 +127,9 @@ export class EditRelationshipComponent implements OnChanges {
         ) as DeleteRelationship;
       }),
       take(1),
-    ).subscribe((deleteRelationship: DeleteRelationship) =>
-      this.objectUpdatesService.saveRemoveFieldUpdate(this.url, deleteRelationship)
-    );
+    ).subscribe((deleteRelationship: DeleteRelationship) => {
+      this.objectUpdatesService.saveRemoveFieldUpdate(this.url, deleteRelationship);
+    });
   }
 
   openVirtualMetadataModal(content: any) {

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

@@ -27,8 +27,7 @@
               [item]="item"
               [itemType]="entityType$ | async"
               [relationshipType]="relationshipType"
-              [hasChanges] = hasChanges()
-              (submit) = submit()
+              [hasChanges]="hasChanges()"
             ></ds-edit-relationship-list>
           </div>
         </ng-container>

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

@@ -4,7 +4,7 @@ import {
   DeleteRelationship,
   RelationshipIdentifiable,
 } from '../../../core/data/object-updates/object-updates.reducer';
-import { map, switchMap, take, concatMap, toArray } from 'rxjs/operators';
+import { map, switchMap, take, concatMap, toArray, tap } from 'rxjs/operators';
 import {
   combineLatest as observableCombineLatest,
   Observable,
@@ -34,6 +34,7 @@ import { FieldChangeType } from '../../../core/data/object-updates/field-change-
 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';
 
 @Component({
   selector: 'ds-item-relationships',
@@ -70,6 +71,7 @@ export class ItemRelationshipsComponent extends AbstractItemUpdateComponent {
     protected relationshipTypeService: RelationshipTypeDataService,
     public cdr: ChangeDetectorRef,
     protected modalService: NgbModal,
+    protected editItemRelationshipsService: EditItemRelationshipsService,
   ) {
     super(itemService, objectUpdatesService, router, notificationsService, translateService, route);
   }
@@ -108,152 +110,14 @@ export class ItemRelationshipsComponent extends AbstractItemUpdateComponent {
    * Make sure the lists are refreshed afterwards and notifications are sent for success and errors
    */
   public submit(): void {
-
-    // Get all the relationships that should be removed
-    const removeUpdates$: Observable<FieldUpdate[]> = this.relationshipService.getItemRelationshipsArray(this.item).pipe(
-      map((relationships: Relationship[]) => relationships.map((relationship) =>
-        Object.assign(new Relationship(), relationship, { uuid: relationship.id })
-      )),
-      switchMap((relationships: Relationship[]) => {
-        return this.objectUpdatesService.getFieldUpdatesExclusive(this.url, relationships) as Observable<FieldUpdates>;
-      }),
-      map((fieldUpdates: FieldUpdates) =>
-        Object.values(fieldUpdates)
-          .filter((fieldUpdate: FieldUpdate) => fieldUpdate.changeType === FieldChangeType.REMOVE)
-      ),
-      take(1)
-    );
-
-    const addUpdates$: Observable<FieldUpdate[]> = this.objectUpdatesService.getFieldUpdates(this.url, []).pipe(
-      map((fieldUpdates: FieldUpdates) =>
-        Object.values(fieldUpdates)
-          .filter((fieldUpdate: FieldUpdate) => hasValue(fieldUpdate))
-          .filter((fieldUpdate: FieldUpdate) => fieldUpdate.changeType === FieldChangeType.ADD)
-      ),
-      take(1)
-    );
-
-    observableCombineLatest([
-      removeUpdates$,
-      addUpdates$,
-    ]).pipe(
-      take(1),
-      switchMap(([removeUpdates, addUpdates]) => [...removeUpdates, ...addUpdates]),
-      concatMap((update: FieldUpdate) => {
-        if (update.changeType === FieldChangeType.REMOVE) {
-          return this.deleteRelationship(update.field as DeleteRelationship).pipe(take(1));
-        } else if (update.changeType === FieldChangeType.ADD) {
-          return this.addRelationship(update.field as RelationshipIdentifiable).pipe(
-            take(1),
-            switchMap((relationshipRD: RemoteData<Relationship>) => {
-              if (relationshipRD.hasSucceeded) {
-                // Set the newly related item to stale, so its relationships will update to include
-                // the new one. Only set the current item to stale at the very end so we only do it
-                // once
-                const { leftItem, rightItem } = relationshipRD.payload._links;
-                if (leftItem.href === this.item.self) {
-                  return this.itemService.invalidateByHref(rightItem.href).pipe(
-                    // when it's invalidated, emit the original relationshipRD for use in the pipe below
-                    map(() => relationshipRD)
-                  );
-                } else {
-                  return this.itemService.invalidateByHref(leftItem.href).pipe(
-                    // when it's invalidated, emit the original relationshipRD for use in the pipe below
-                    map(() => relationshipRD)
-                  );
-                }
-              } else {
-                return [relationshipRD];
-              }
-            })
-          );
-        } else {
-          return EMPTY;
-        }
-      }),
-      toArray(),
-      switchMap((responses) => {
-        // once all relationships are made and all related items have been invalidated, invalidate
-        // the current item
-        return this.itemService.invalidateByHref(this.item.self).pipe(
-          map(() => responses)
-        );
-      })
-    ).subscribe((responses) => {
-      if (responses.length > 0) {
-        this.initializeOriginalFields();
-        this.displayNotifications(responses);
-        this.modalService.dismissAll();
-      }
-    });
+    this.editItemRelationshipsService.submit(this.item, this.url);
   }
 
-  deleteRelationship(deleteRelationship: DeleteRelationship): Observable<RemoteData<NoContent>> {
-    let copyVirtualMetadata: string;
-    if (deleteRelationship.keepLeftVirtualMetadata && deleteRelationship.keepRightVirtualMetadata) {
-      copyVirtualMetadata = 'all';
-    } else if (deleteRelationship.keepLeftVirtualMetadata) {
-      copyVirtualMetadata = 'left';
-    } else if (deleteRelationship.keepRightVirtualMetadata) {
-      copyVirtualMetadata = 'right';
-    } else {
-      copyVirtualMetadata = 'none';
-    }
-
-    return this.relationshipService.deleteRelationship(deleteRelationship.uuid, copyVirtualMetadata, false);
-  }
-
-  addRelationship(addRelationship: RelationshipIdentifiable): Observable<RemoteData<Relationship>> {
-    return this.entityType$.pipe(
-      switchMap((entityType) => this.entityTypeService.isLeftType(addRelationship.type, entityType)),
-      switchMap((isLeftType) => {
-        let leftItem: Item;
-        let rightItem: Item;
-        let leftwardValue: string;
-        let rightwardValue: string;
-        if (isLeftType) {
-          leftItem = this.item;
-          rightItem = addRelationship.relatedItem;
-          leftwardValue = null;
-          rightwardValue = addRelationship.nameVariant;
-        } else {
-          leftItem = addRelationship.relatedItem;
-          rightItem = this.item;
-          leftwardValue = addRelationship.nameVariant;
-          rightwardValue = null;
-        }
-        return this.relationshipService.addRelationship(addRelationship.type.id, leftItem, rightItem, leftwardValue, rightwardValue, false);
-      }),
-    );
-
-  }
-
-  /**
-   * Display notifications
-   * - Error notification for each failed response with their message
-   * - Success notification in case there's at least one successful response
-   * @param responses
-   */
-  displayNotifications(responses: RemoteData<NoContent>[]) {
-    const failedResponses = responses.filter((response: RemoteData<NoContent>) => response.hasFailed);
-    const successfulResponses = responses.filter((response: RemoteData<NoContent>) => response.hasSucceeded);
-
-    failedResponses.forEach((response: RemoteData<NoContent>) => {
-      this.notificationsService.error(this.getNotificationTitle('failed'), response.errorMessage);
-    });
-    if (successfulResponses.length > 0) {
-      this.notificationsService.success(this.getNotificationTitle('saved'), this.getNotificationContent('saved'));
-    }
-  }
   /**
    * Sends all initial values of this item to the object updates service
    */
   public initializeOriginalFields() {
-    return this.relationshipService.getRelatedItems(this.item).pipe(
-      take(1),
-    ).subscribe((items: Item[]) => {
-      this.objectUpdatesService.initialize(this.url, items, this.item.lastModified);
-    });
+    return this.editItemRelationshipsService.initializeOriginalFields(this.item, this.url);
   }