From 9ebd5a40668e5dd23e83277f5ad1a5c219146811 Mon Sep 17 00:00:00 2001
From: Lee Wexler <lbwexler@xh.io>
Date: Tue, 31 Dec 2024 14:19:37 -0500
Subject: [PATCH] Tighten/simplify implementation of HoistModel.componentProps
 (#3883)

- Fix difficult bug with re-render loops.
- Avoid mobx object/proxy object creation for models that don't use this property
- Avoid extra prop processing for linked models that don't use this property
---
 core/model/HoistModel.ts | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/core/model/HoistModel.ts b/core/model/HoistModel.ts
index 538730216..bd076e23b 100644
--- a/core/model/HoistModel.ts
+++ b/core/model/HoistModel.ts
@@ -4,9 +4,9 @@
  *
  * Copyright © 2025 Extremely Heavy Industries Inc.
  */
-import {action, makeObservable, observable} from '@xh/hoist/mobx';
+import {action, computed, comparer, makeObservable, observable} from '@xh/hoist/mobx';
 import {warnIf} from '@xh/hoist/utils/js';
-import {forOwn, has, isFunction} from 'lodash';
+import {isFunction} from 'lodash';
 import {DefaultHoistProps, HoistBase, LoadSpecConfig, managed, PlainObject} from '../';
 import {instanceManager} from '../impl/InstanceManager';
 import {Loadable, LoadSpec, LoadSupport} from '../load';
@@ -67,8 +67,7 @@ export abstract class HoistModel extends HoistBase implements Loadable {
     }
 
     // Internal State
-    @observable
-    _componentProps = {};
+    @observable.ref _componentProps = null;
     _modelLookup = null;
     _created = Date.now();
 
@@ -136,6 +135,7 @@ export abstract class HoistModel extends HoistBase implements Loadable {
      * Observability is based on a shallow computation for each prop (i.e. a reference
      * change in any particular prop will trigger observers to be notified).
      */
+    @computed({equals: comparer.shallow})
     get componentProps(): DefaultHoistProps {
         return this._componentProps;
     }
@@ -187,13 +187,7 @@ export abstract class HoistModel extends HoistBase implements Loadable {
     /** @internal */
     @action
     setComponentProps(newProps) {
-        const props = this._componentProps;
-        Object.assign(props, newProps);
-        forOwn(props, (v, k) => {
-            if (!has(newProps, k)) {
-                delete props[k];
-            }
-        });
+        this._componentProps = newProps;
     }
 
     /** @internal */