DEV: Ensure `post.updateFromPost` syncs tracked properties (#29970)

This commit ensures that tracked properties added to the post model are correctly synced when using `post.updateFromPost`.

It also introduces a plugin API to allow plugins to register new tracked properties in the post model without needing to modify the class.

app/assets/javascripts/discourse/app/lib/plugin-api.gjs

@@ -3,7 +3,7 @@
 // docs/CHANGELOG-JAVASCRIPT-PLUGIN-API.md whenever you change the version
 // using the format described at https://keepachangelog.com/en/1.0.0/.
 
-export const PLUGIN_API_VERSION = "1.38.0";
+export const PLUGIN_API_VERSION = "1.39.0";
 
 import $ from "jquery";
 import { h } from "virtual-dom";
@@ -119,6 +119,7 @@ import Composer, {
   registerCustomizationCallback,
 } from "discourse/models/composer";
 import { addNavItem } from "discourse/models/nav-item";
+import { _addTrackedPostProperty } from "discourse/models/post";
 import { registerCustomLastUnreadUrlCallback } from "discourse/models/topic";
 import {
   addSaveableUserField,
@@ -819,6 +820,17 @@ class PluginApi {
     includeAttributes(...attributes);
   }
 
+  /**
+   * Adds a tracked property to the post model.
+   *
+   * This method is used to mark a property as tracked for post updates.
+   *
+   * @param {string} name - The name of the property to track.
+   */
+  addTrackedPostProperty(name) {
+    _addTrackedPostProperty(name);
+  }
+
   /**
    * Add a new button below a post with your plugin.
    *

app/assets/javascripts/discourse/app/models/post.js

@@ -10,6 +10,7 @@ import { popupAjaxError } from "discourse/lib/ajax-error";
 import { propertyEqual } from "discourse/lib/computed";
 import { cook } from "discourse/lib/text";
 import { fancyTitle } from "discourse/lib/topic-fancy-title";
+import { defineTrackedProperty } from "discourse/lib/tracked-tools";
 import { userPath } from "discourse/lib/url";
 import { postUrl } from "discourse/lib/utilities";
 import ActionSummary from "discourse/models/action-summary";
@@ -20,6 +21,46 @@ import User from "discourse/models/user";
 import discourseComputed from "discourse-common/utils/decorators";
 import { i18n } from "discourse-i18n";
 
+const pluginTrackedProperties = new Set();
+const trackedPropertiesForPostUpdate = new Set();
+
+/**
+ * @internal
+ * Adds a tracked property to the post model.
+ *
+ * Intended to be used only in the plugin API.
+ *
+ * @param {string} propertyKey - The key of the property to track.
+ */
+export function _addTrackedPostProperty(propertyKey) {
+  pluginTrackedProperties.add(propertyKey);
+}
+
+/**
+ * Clears all tracked properties added using the API
+ *
+ * USE ONLY FOR TESTING PURPOSES.
+ */
+export function clearAddedTrackedPostProperties() {
+  pluginTrackedProperties.clear();
+}
+
+/**
+ * Decorator to mark a property as post property as tracked.
+ *
+ * It extends the standard Ember @tracked behavior to also keep track of the fields
+ * that need to be copied when using `post.updateFromPost`.
+ *
+ * @param {Object} target - The target object.
+ * @param {string} propertyKey - The key of the property to track.
+ * @param {PropertyDescriptor} descriptor - The property descriptor.
+ * @returns {PropertyDescriptor} The updated property descriptor.
+ */
+function trackedPostProperty(target, propertyKey, descriptor) {
+  trackedPropertiesForPostUpdate.add(propertyKey);
+  return tracked(target, propertyKey, descriptor);
+}
+
 export default class Post extends RestModel {
   static munge(json) {
     if (json.actions_summary) {
@@ -107,17 +148,22 @@ export default class Post extends RestModel {
   @service currentUser;
   @service site;
 
-  @tracked bookmarked;
-  @tracked can_delete;
-  @tracked can_edit;
-  @tracked can_permanently_delete;
-  @tracked can_recover;
-  @tracked deleted_at;
-  @tracked likeAction;
-  @tracked post_type;
-  @tracked user_deleted;
-  @tracked user_id;
-  @tracked yours;
+  // Use @trackedPostProperty here instead of Glimmer's @tracked because we need to know which properties are tracked
+  // in order to correctly update the post in the updateFromPost method. Currently this is not possible using only
+  // the standard tracked method because these properties are added to the class prototype and are not enumarated by
+  // object.keys().
+  // See https://github.com/emberjs/ember.js/issues/18220
+  @trackedPostProperty bookmarked;
+  @trackedPostProperty can_delete;
+  @trackedPostProperty can_edit;
+  @trackedPostProperty can_permanently_delete;
+  @trackedPostProperty can_recover;
+  @trackedPostProperty deleted_at;
+  @trackedPostProperty likeAction;
+  @trackedPostProperty post_type;
+  @trackedPostProperty user_deleted;
+  @trackedPostProperty user_id;
+  @trackedPostProperty yours;
 
   customShare = null;
 
@@ -132,6 +178,15 @@ export default class Post extends RestModel {
   // Posts can show up as deleted if the topic is deleted
   @and("firstPost", "topic.deleted_at") deletedViaTopic;
 
+  constructor() {
+    super(...arguments);
+
+    // adds tracked properties defined by plugin to the instance
+    pluginTrackedProperties.forEach((propertyKey) => {
+      defineTrackedProperty(this, propertyKey);
+    });
+  }
+
   @discourseComputed("url", "customShare")
   shareUrl(url) {
     return this.customShare || resolveShareUrl(url, this.currentUser);
@@ -466,11 +521,15 @@ export default class Post extends RestModel {
   }
 
   /**
-   Updates a post from another's attributes. This will normally happen when a post is loading but
-   is already found in an identity map.
+   * Updates a post from another's attributes. This will normally happen when a post is loading but
+   * is already found in an identity map.
    **/
   updateFromPost(otherPost) {
-    Object.keys(otherPost).forEach((key) => {
+    [
+      ...Object.keys(otherPost),
+      ...trackedPropertiesForPostUpdate,
+      ...pluginTrackedProperties,
+    ].forEach((key) => {
       let value = otherPost[key],
         oldValue = this[key];
 

app/assets/javascripts/discourse/tests/helpers/qunit-helpers.js

@@ -82,6 +82,7 @@ import { resetUserSearchCache } from "discourse/lib/user-search";
 import { resetComposerCustomizations } from "discourse/models/composer";
 import { clearAuthMethods } from "discourse/models/login-method";
 import { clearNavItems } from "discourse/models/nav-item";
+import { clearAddedTrackedPostProperties } from "discourse/models/post";
 import { resetLastEditNotificationClick } from "discourse/models/post-stream";
 import Site from "discourse/models/site";
 import User from "discourse/models/user";
@@ -257,6 +258,7 @@ export function testCleanup(container, app) {
   clearPluginHeaderActionComponents();
   clearRegisteredTabs();
   resetNeedsHbrTopicList();
+  clearAddedTrackedPostProperties();
 }
 
 function cleanupCssGeneratorTags() {

app/assets/javascripts/discourse/tests/unit/models/post-test.js

@@ -1,6 +1,7 @@
 import { getOwner } from "@ember/owner";
 import { setupTest } from "ember-qunit";
 import { module, test } from "qunit";
+import { withPluginApi } from "discourse/lib/plugin-api";
 
 module("Unit | Model | post", function (hooks) {
   setupTest(hooks);
@@ -32,18 +33,36 @@ module("Unit | Model | post", function (hooks) {
   });
 
   test("updateFromPost", function (assert) {
+    withPluginApi("1.39.0", (api) => {
+      api.addTrackedPostProperty("plugin_property");
+    });
+
     const post = this.store.createRecord("post", {
       post_number: 1,
       raw: "hello world",
+      likeAction: null, // `likeAction` is a tracked property from the model added using `@trackedPostProperty`
     });
 
     post.updateFromPost(
       this.store.createRecord("post", {
         raw: "different raw",
+        yours: false,
+        likeAction: { count: 1 },
+        plugin_property: "different plugin value",
       })
     );
 
-    assert.strictEqual(post.raw, "different raw", "raw field updated");
+    assert.strictEqual(post.raw, "different raw", "`raw` field was updated");
+    assert.deepEqual(
+      post.likeAction,
+      { count: 1 },
+      "`likeAction` field was updated"
+    );
+    assert.strictEqual(
+      post.plugin_property,
+      "different plugin value",
+      "`plugin_property` field was updated"
+    );
   });
 
   test("destroy by staff", async function (assert) {

docs/CHANGELOG-JAVASCRIPT-PLUGIN-API.md

@@ -7,6 +7,10 @@ in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.39.0] - 2024-11-27
+
+- Added `addTrackedPostProperty` which allows plugins/TCs to add a new tracked property to the post model.
+
 ## [1.38.0] - 2024-10-30
 
 - Added `registerMoreTopicsTab` and "more-topics-tabs" value transformer that allows to add or remove new tabs to the "more topics" (suggested/related) area.