From 4ccd459b1a4d560a2abbf8806a407fac92fe13ca Mon Sep 17 00:00:00 2001
From: Alexandre Vryghem <alexandre@atmire.com>
Date: Mon, 3 Jun 2024 13:50:42 +0200
Subject: [PATCH] 115046: Fixed issue where relationsToItems would never emit
 when an empty array was passed to it

---
 .../shared/item-relationships-utils.ts        | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/app/item-page/simple/item-types/shared/item-relationships-utils.ts b/src/app/item-page/simple/item-types/shared/item-relationships-utils.ts
index 112884303b..6b9f100df4 100644
--- a/src/app/item-page/simple/item-types/shared/item-relationships-utils.ts
+++ b/src/app/item-page/simple/item-types/shared/item-relationships-utils.ts
@@ -2,6 +2,7 @@ import { InjectionToken } from '@angular/core';
 import {
   combineLatest as observableCombineLatest,
   Observable,
+  of as observableOf,
   zip as observableZip,
 } from 'rxjs';
 import {
@@ -53,17 +54,19 @@ export const compareArraysUsingIds = <T extends { id: string }>() =>
 /**
  * Operator for turning a list of relationships into a list of the relevant items
  * @param {string} thisId       The item's id of which the relations belong to
- * @returns {(source: Observable<Relationship[]>) => Observable<Item[]>}
  */
-export const relationsToItems = (thisId: string) =>
+export const relationsToItems = (thisId: string): (source: Observable<Relationship[]>) => Observable<Item[]> =>
   (source: Observable<Relationship[]>): Observable<Item[]> =>
     source.pipe(
-      mergeMap((rels: Relationship[]) =>
-        observableZip(
-          ...rels.map((rel: Relationship) => observableCombineLatest(rel.leftItem, rel.rightItem)),
-        ),
-      ),
-      map((arr) =>
+      mergeMap((relationships: Relationship[]) => {
+        if (relationships.length === 0) {
+          return observableOf([]);
+        }
+        return observableZip(
+          ...relationships.map((rel: Relationship) => observableCombineLatest([rel.leftItem, rel.rightItem])),
+        );
+      }),
+      map((arr: [RemoteData<Item>, RemoteData<Item>][]) =>
         arr
           .filter(([leftItem, rightItem]) => leftItem.hasSucceeded && rightItem.hasSucceeded)
           .map(([leftItem, rightItem]) => {