From 5a843bc90986a29ec0375697490af9864ecbd188 Mon Sep 17 00:00:00 2001
From: Luke Towers <github@luketowers.ca>
Date: Sun, 23 Aug 2020 23:57:05 -0600
Subject: [PATCH] Fix support for updating belongsTo relationships with the
 RelationController.

Fixes #5198, #5243; replaces #5217. Related: https://github.com/octobercms/october/commit/6e25c5a8d0834aa083455f9f2b7c75b9bda7ff1c#
---
 modules/backend/behaviors/RelationController.php | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/modules/backend/behaviors/RelationController.php b/modules/backend/behaviors/RelationController.php
index f6c96382d..c8becee6b 100644
--- a/modules/backend/behaviors/RelationController.php
+++ b/modules/backend/behaviors/RelationController.php
@@ -1157,7 +1157,11 @@ class RelationController extends ControllerBehavior
             }
         }
         elseif ($this->viewMode == 'single') {
-            $this->viewModel = $this->manageWidget->model;
+            // Ensure that the view widget model is the same instance as the manage widget model
+            // since they will technically be different object instances in this context as
+            // $viewWidet->model is populated by $this->relationModel->getResults() and
+            // $manageWidget->model is populated by $this->relationModel->find($manageId);
+            $this->viewModel = $this->viewWidget->model = $this->manageWidget->model;
 
             $this->viewWidget->setFormValues($saveData);
             $this->viewModel->save(null, $this->manageWidget->getSessionKey());