From eeccf4c765510e7b42c633a29ecdc8beae2a9665 Mon Sep 17 00:00:00 2001
From: Kieran Marshall <kieran.marshall@agentsoftware.net>
Date: Thu, 11 Nov 2021 09:01:00 +0000
Subject: [PATCH] Allow child types to be set via a method.

---
 src/HasChildren.php            | 22 ++++++++++++----------
 tests/Unit/HasChildrenTest.php | 24 ++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/src/HasChildren.php b/src/HasChildren.php
index 97d977d..c720ad7 100644
--- a/src/HasChildren.php
+++ b/src/HasChildren.php
@@ -14,11 +14,13 @@ protected static function registerModelEvent($event, $callback)
     {
         parent::registerModelEvent($event, $callback);
 
-        if (static::class === self::class && property_exists(self::class, 'childTypes')) {
+        $childTypes = (new self)->getChildTypes();
+
+        if (static::class === self::class && $childTypes !== []) {
             // We don't want to register the callbacks that happen in the boot method of the parent, as they'll be called
             // from the child's boot method as well.
             if (! self::parentIsBooting()) {
-                foreach ((new self)->childTypes as $childClass) {
+                foreach ($childTypes as $childClass) {
                     if ($childClass !== self::class) {
                         $childClass::registerModelEvent($event, $callback);
                     }
@@ -193,10 +195,10 @@ protected function getChildModel(array $attributes)
      */
     public function classFromAlias($aliasOrClass)
     {
-        if (property_exists($this, 'childTypes')) {
-            if (isset($this->childTypes[$aliasOrClass])) {
-                return $this->childTypes[$aliasOrClass];
-            }
+        $childTypes = $this->getChildTypes();
+
+        if (isset($childTypes[$aliasOrClass])) {
+            return $childTypes[$aliasOrClass];
         }
 
         return $aliasOrClass;
@@ -208,10 +210,10 @@ public function classFromAlias($aliasOrClass)
      */
     public function classToAlias($className)
     {
-        if (property_exists($this, 'childTypes')) {
-            if (in_array($className, $this->childTypes)) {
-                return array_search($className, $this->childTypes);
-            }
+        $childTypes = $this->getChildTypes();
+
+        if (in_array($className, $childTypes)) {
+            return array_search($className, $childTypes);
         }
 
         return $className;
diff --git a/tests/Unit/HasChildrenTest.php b/tests/Unit/HasChildrenTest.php
index d1a03c5..972ae25 100644
--- a/tests/Unit/HasChildrenTest.php
+++ b/tests/Unit/HasChildrenTest.php
@@ -18,6 +18,17 @@ function child_model_mutators_are_not_instigated()
 
         $this->assertEquals($model->mutatorWasCalled, false);
     }
+
+    /** @test */
+    function child_model_types_can_be_set_via_method()
+    {
+        $types = (new HasChildrenParentModelWithMethodTypes)->getChildTypes();
+
+        $this->assertEquals([
+            'foo' => Foo::class,
+            'bar' => Bar::class,
+        ], $types);
+    }
 }
 
 class HasChildrenParentModel extends Model {
@@ -34,3 +45,16 @@ public function setTestAttribute()
         $this->mutatorWasCalled = true;
     }
 }
+
+class HasChildrenParentModelWithMethodTypes extends Model
+{
+    use HasChildren;
+
+    public function getChildTypes()
+    {
+        return [
+            'foo' => Foo::class,
+            'bar' => Bar::class,
+        ];
+    }
+}