ElementArguments::EVENT_DEFINE_ARGUMENTS

Resolves #18062

Author: brandonkelly

CHANGELOG-WIP.md

@@ -58,6 +58,7 @@
 - Added `craft\elements\User::isInGroups()`. ([#17989](https://github.com/craftcms/cms/discussions/17989))
 - Added `craft\elements\conditions\HintableConditionRuleTrait`. ([#17909](https://github.com/craftcms/cms/pull/17909))
 - Added `craft\events\DefineFieldActionsEvent`.
+- Added `craft\events\DefineGqlArgumentsEvent`.
 - Added `craft\events\RegisterElementCardAttributesEvent::$fieldLayout`. ([#17920](https://github.com/craftcms/cms/pull/17920))
 - Added `craft\fieldlayoutelements\BaseField::EVENT_DEFINE_ACTION_MENU_ITEMS`. ([#18037](https://github.com/craftcms/cms/issues/18037))
 - Added `craft\fields\BaseRelationField::VIEW_MODE_CARDS_GRID`.
@@ -66,6 +67,7 @@
 - Added `craft\fields\BaseRelationField::VIEW_MODE_LIST`.
 - Added `craft\fields\BaseRelationField::VIEW_MODE_THUMBS`.
 - Added `craft\fields\Matrix::VIEW_MODE_CARDS_GRID`.
+- Added `craft\gql\base\ElementArguments::EVENT_DEFINE_ARGUMENTS`. ([#18062](https://github.com/craftcms/cms/discussions/18062))
 - Added `craft\helpers\ElementHelper::loadProvisionalChanges()`. ([#17915](https://github.com/craftcms/cms/pull/17915))
 - Added `craft\models\EntryType::$uiLabelFormat`.
 - Added `craft\services\ElementSources::getFirstPage()`. ([#17779](https://github.com/craftcms/cms/pull/17779))

src/events/DefineGqlArgumentsEvent.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * @link https://craftcms.com/
+ * @copyright Copyright (c) Pixel & Tonic, Inc.
+ * @license https://craftcms.github.io/license/
+ */
+
+namespace craft\events;
+
+use craft\base\Event;
+
+/**
+ * DefineGqlArgumentsEvent class.
+ *
+ * @author Pixel & Tonic, Inc. <[email protected]>
+ * @since 5.9.0
+ */
+class DefineGqlArgumentsEvent extends Event
+{
+    /**
+     * @var array<array|object> List of arguments
+     */
+    public array $arguments = [];
+}

src/gql/base/ElementArguments.php

@@ -7,6 +7,8 @@
 
 namespace craft\gql\base;
 
+use craft\base\Event;
+use craft\events\DefineGqlArgumentsEvent;
 use craft\gql\GqlEntityRegistry;
 use craft\gql\types\input\criteria\AssetRelation;
 use craft\gql\types\input\criteria\CategoryRelation;
@@ -26,12 +28,18 @@
  */
 abstract class ElementArguments extends Arguments
 {
+    /**
+     * @event DefineGqlArgumentsEvent The event that is triggered when arguments are being defined.
+     * @since 5.9.0
+     */
+    public const EVENT_DEFINE_ARGUMENTS = 'defineArguments';
+
     /**
      * @inheritdoc
      */
     public static function getArguments(): array
     {
-        return array_merge(parent::getArguments(), static::getDraftArguments(), static::getRevisionArguments(), static::getStatusArguments(), [
+        $arguments = array_merge(parent::getArguments(), static::getDraftArguments(), static::getRevisionArguments(), static::getStatusArguments(), [
             'site' => [
                 'name' => 'site',
                 'type' => Type::listOf(Type::string()),
@@ -193,6 +201,14 @@ public static function getArguments(): array
                 'description' => 'Narrows the query results based on the unique identifier for an element-site relation.',
             ],
         ]);
+
+        if (Event::hasHandlers(self::class, self::EVENT_DEFINE_ARGUMENTS)) {
+            $event = new DefineGqlArgumentsEvent(compact('arguments'));
+            Event::trigger(self::class, self::EVENT_DEFINE_ARGUMENTS, $event);
+            return $event->arguments;
+        }
+
+        return $arguments;
     }
 
     /**