[DURACOM-304] Refactored relationship-type-data.service.ts by removing page size of 9999

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

@@ -1,5 +1,5 @@
 import { Injectable } from '@angular/core';
-import { combineLatest as observableCombineLatest, Observable } from 'rxjs';
+import { combineLatest as observableCombineLatest, EMPTY, expand, from, Observable, reduce } from 'rxjs';
 import { map, mergeMap, switchMap, toArray } from 'rxjs/operators';
 import { hasValue } from '../../shared/empty.util';
 import { followLink, FollowLinkConfig } from '../../shared/utils/follow-link-config.model';
@@ -62,11 +62,26 @@ export class RelationshipTypeDataService extends BaseDataService<RelationshipTyp
    */
   getRelationshipTypeByLabelAndTypes(relationshipTypeLabel: string, firstItemType: string, secondItemType: string): Observable<RelationshipType> {
     // Retrieve all relationship types from the server in a single page
-    return this.findAllData.findAll({ currentPage: 1, elementsPerPage: 9999 }, true, true, followLink('leftType'), followLink('rightType'))
+    const initialPageInfo = { currentPage: 1, elementsPerPage: 20 };
+    return this.findAllData.findAll(initialPageInfo, true, true, followLink('leftType'), followLink('rightType'))
       .pipe(
         getFirstSucceededRemoteData(),
         // Emit each type in the page array separately
-                 switchMap((typeListRD: RemoteData<PaginatedList<RelationshipType>>) => typeListRD.payload.page),
+        expand((typeListRD: RemoteData<PaginatedList<RelationshipType>>) => {
+          const currentPage = typeListRD.payload.pageInfo.currentPage;
+          const totalPages = typeListRD.payload.pageInfo.totalPages;
+          if (currentPage < totalPages) {
+            const nextPageInfo = { currentPage: currentPage + 1, elementsPerPage: 20 };
+            return this.findAllData.findAll(nextPageInfo, true, true, followLink('leftType'), followLink('rightType')).pipe(
+              getFirstSucceededRemoteData()
+            );
+          } else {
+            return EMPTY;
+          }
+        }),
+        // Collect all pages into a single array
+        reduce((acc: RelationshipType[], typeListRD: RemoteData<PaginatedList<RelationshipType>>) => acc.concat(typeListRD.payload.page), []),
+        mergeMap((relationshipTypes: RelationshipType[]) => from(relationshipTypes)),
         // Check each type individually, to see if it matches the provided types
         mergeMap((relationshipType: RelationshipType) => {
           if (relationshipType.leftwardType === relationshipTypeLabel) {