Update 3.relationships.md

Author: GautierDele

content/3.resources/3.relationships.md

@@ -156,6 +156,26 @@ MorphTo::make('commentable', PostResource::class),
 
 ::callout{icon="i-heroicons-exclamation-triangle" color="amber"}
 You must specify multiple relations for each morph to resource possible. Please consider declaring multiple relations in your model.
+
+::collapsible{name="relations"}
+```php
+// You can't declare this relation in Laravel Rest Api
+public function commentable(): MorphTo
+{
+    return $this->morphTo();
+}
+
+public function post(): MorphTo
+{
+    return $this->morphTo()->where('commentable_type', Post::class);
+}
+
+public function video(): MorphTo
+{
+    return $this->morphTo()->where('commentable_type', Video::class);
+}
+```
+::
 ::
 
 ## Morph To Many