FEATURE: Introduce `api.renderInOutlet` (#23719)

Until now, plugins/themes had to follow very specific directory structures to set up plugin outlet connectors. This commit introduces a new `api.renderInOutlet` API which makes things much more flexible. Any Ember component definition can be passed to this API, and will then be rendered into the named outlet.

For example:

```javascript
import MyComponent from "discourse/plugins/my-plugin/components/my-component";
api.renderInOutlet('user-profile-primary', MyComponent);
```

When using this API alongside the gjs file format, components can be defined inline like

```javascript
api.renderInOutlet('user-profile-primary', <template>Hello world</template>);
```

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

@@ -77,7 +77,10 @@ import { addUsernameSelectorDecorator } from "discourse/helpers/decorate-usernam
 import { addWidgetCleanCallback } from "discourse/components/mount-widget";
 import deprecated from "discourse-common/lib/deprecated";
 import { disableNameSuppression } from "discourse/widgets/poster-name";
-import { extraConnectorClass } from "discourse/lib/plugin-connectors";
+import {
+  extraConnectorClass,
+  extraConnectorComponent,
+} from "discourse/lib/plugin-connectors";
 import { getOwnerWithFallback } from "discourse-common/lib/get-owner";
 import { h } from "virtual-dom";
 import { includeAttributes } from "discourse/lib/transform-post";
@@ -134,7 +137,7 @@ import { isTesting } from "discourse-common/config/environment";
 // 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 = "1.12.0";
+export const PLUGIN_API_VERSION = "1.13.0";
 
 // This helper prevents us from applying the same `modifyClass` over and over in test mode.
 function canModify(klass, type, resolverName, changes) {
@@ -940,6 +943,31 @@ class PluginApi {
     extraConnectorClass(`${outletName}/${connectorName}`, klass);
   }
 
+  /**
+   * Register a component to be rendered in a particular outlet.
+   *
+   * For example, if the outlet is `user-profile-primary`, you could register
+   * a component like
+   *
+   * ```javascript
+   * import MyComponent from "discourse/plugins/my-plugin/components/my-component";
+   * api.renderInOutlet('user-profile-primary', MyComponent);
+   * ```
+   *
+   * Alternatively, a component could be defined inline using gjs:
+   *
+   * ```javascript
+   * api.renderInOutlet('user-profile-primary', <template>Hello world</template>);
+   * ```
+   *
+   * @param {string} outletName - Name of plugin outlet to render into
+   * @param {Component} klass - Component class definition to be rendered
+   *
+   */
+  renderInOutlet(outletName, klass) {
+    extraConnectorComponent(outletName, klass);
+  }
+
   /**
    * Register a button to display at the bottom of a topic
    *

app/assets/javascripts/discourse/app/lib/plugin-connectors.js

@@ -10,9 +10,11 @@ import templateOnly from "@ember/component/template-only";
 let _connectorCache;
 let _rawConnectorCache;
 let _extraConnectorClasses = {};
+let _extraConnectorComponents = {};
 
 export function resetExtraClasses() {
   _extraConnectorClasses = {};
+  _extraConnectorComponents = {};
 }
 
 // Note: In plugins, define a class by path and it will be wired up automatically
@@ -21,6 +23,17 @@ export function extraConnectorClass(name, obj) {
   _extraConnectorClasses[name] = obj;
 }
 
+export function extraConnectorComponent(outletName, klass) {
+  if (!hasInternalComponentManager(klass)) {
+    throw new Error("klass is not an Ember component");
+  }
+  if (outletName.includes("/")) {
+    throw new Error("invalid outlet name");
+  }
+  _extraConnectorComponents[outletName] ??= [];
+  _extraConnectorComponents[outletName].push(klass);
+}
+
 const OUTLET_REGEX =
   /^discourse(\/[^\/]+)*?(?<template>\/templates)?\/connectors\/(?<outlet>[^\/]+)\/(?<name>[^\/\.]+)$/;
 
@@ -87,7 +100,9 @@ class ConnectorInfo {
 
   get connectorClass() {
     if (this.classModule) {
-      return require(this.classModule).default;
+      return this.classModule;
+    } else if (this.classModuleName) {
+      return require(this.classModuleName).default;
     } else {
       return _extraConnectorClasses[`${this.outletName}/${this.connectorName}`];
     }
@@ -101,7 +116,7 @@ class ConnectorInfo {
 
   get humanReadableName() {
     return `${this.outletName}/${this.connectorName} (${
-      this.classModule || this.templateModule
+      this.classModuleName || this.templateModule
     })`;
   }
 
@@ -160,7 +175,7 @@ function buildConnectorCache() {
       if (isTemplate) {
         info.templateModule = moduleName;
       } else {
-        info.classModule = moduleName;
+        info.classModuleName = moduleName;
       }
     }
   );
@@ -169,6 +184,18 @@ function buildConnectorCache() {
     _connectorCache[info.outletName] ??= [];
     _connectorCache[info.outletName].push(info);
   }
+
+  for (const [outletName, components] of Object.entries(
+    _extraConnectorComponents
+  )) {
+    for (const klass of components) {
+      const info = new ConnectorInfo(outletName);
+      info.classModule = klass;
+
+      _connectorCache[info.outletName] ??= [];
+      _connectorCache[info.outletName].push(info);
+    }
+  }
 }
 
 export function connectorsExist(outletName) {

app/assets/javascripts/discourse/tests/integration/components/plugin-outlet-test.gjs

@@ -3,14 +3,16 @@ import { count, exists, query } from "discourse/tests/helpers/qunit-helpers";
 import { setupRenderingTest } from "discourse/tests/helpers/component-test";
 import { click, render, settled } from "@ember/test-helpers";
 import { action } from "@ember/object";
-import { extraConnectorClass } from "discourse/lib/plugin-connectors";
+import {
+  extraConnectorClass,
+  extraConnectorComponent,
+} from "discourse/lib/plugin-connectors";
 import { hbs } from "ember-cli-htmlbars";
 import { registerTemporaryModule } from "discourse/tests/helpers/temporary-module-helper";
 import { getOwner } from "@ember/application";
 import Component from "@glimmer/component";
 import templateOnly from "@ember/component/template-only";
 import { withSilencedDeprecationsAsync } from "discourse-common/lib/deprecated";
-import { setComponentTemplate } from "@glimmer/manager";
 import sinon from "sinon";
 
 const TEMPLATE_PREFIX = "discourse/plugins/some-plugin/templates/connectors";
@@ -57,13 +59,13 @@ module("Integration | Component | plugin-outlet", function (hooks) {
     registerTemporaryModule(
       `${TEMPLATE_PREFIX}/test-name/hello`,
       hbs`<span class='hello-username'>{{this.username}}</span>
-        <button class='say-hello' {{on "click" (action "sayHello")}}></button>
-        <button class='say-hello-using-this' {{on "click" this.sayHello}}></button>
+        <button type="button" class='say-hello' {{on "click" (action "sayHello")}}></button>
+        <button type="button" class='say-hello-using-this' {{on "click" this.sayHello}}></button>
         <span class='hello-result'>{{this.hello}}</span>`
     );
     registerTemporaryModule(
       `${TEMPLATE_PREFIX}/test-name/hi`,
-      hbs`<button class='say-hi' {{on "click" (action "sayHi")}}></button>
+      hbs`<button type="button" class='say-hi' {{on "click" (action "sayHi")}}></button>
         <span class='hi-result'>{{this.hi}}</span>`
     );
     registerTemporaryModule(
@@ -427,13 +429,9 @@ module(
     setupRenderingTest(hooks);
 
     hooks.beforeEach(function () {
-      const template = hbs`<span class='gjs-test'>Hello world</span>`;
-      const component = templateOnly();
-      setComponentTemplate(template, component);
-
       registerTemporaryModule(
         `${CLASS_PREFIX}/test-name/my-connector`,
-        component
+        <template><span class="gjs-test">Hello world</span></template>
       );
     });
 
@@ -444,3 +442,21 @@ module(
     });
   }
 );
+
+module(
+  "Integration | Component | plugin-outlet | extraConnectorComponent",
+  function (hooks) {
+    setupRenderingTest(hooks);
+
+    hooks.beforeEach(function () {
+      extraConnectorComponent("test-name", <template>
+        <span class="gjs-test">Hello world from gjs</span>
+      </template>);
+    });
+
+    test("renders the component in the outlet", async function (assert) {
+      await render(hbs`<PluginOutlet @name="test-name" />`);
+      assert.dom(".gjs-test").hasText("Hello world from gjs");
+    });
+  }
+);

docs/CHANGELOG-JAVASCRIPT-PLUGIN-API.md

@@ -7,6 +7,12 @@ 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).
 
+## [1.13.0] - 2023-10-05
+
+### Added
+
+- Introduces `renderInOutlet` API for rendering components into plugin outlets
+
 ## [1.12.0] - 2023-09-06
 
 ### Added