Implement SerializesCastableAttributes in StateCaster

src/StateCaster.php

@@ -3,10 +3,11 @@
 namespace Spatie\ModelStates;
 
 use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
+use Illuminate\Contracts\Database\Eloquent\SerializesCastableAttributes;
 use Illuminate\Support\Collection;
 use Spatie\ModelStates\Exceptions\UnknownState;
 
-class StateCaster implements CastsAttributes
+class StateCaster implements CastsAttributes, SerializesCastableAttributes
 {
     /** @var string|\Spatie\ModelStates\State */
     private string $baseStateClass;
@@ -70,6 +71,19 @@ public function set($model, string $key, $value, array $attributes): ?string
         return $value::getMorphClass();
     }
 
+    /**
+     * @param \Illuminate\Database\Eloquent\Model $model
+     * @param string $key
+     * @param mixed $value
+     * @param array $attributes
+     *
+     * @return mixed
+     */
+    public function serialize($model, string $key, $value, array $attributes)
+    {
+        return $value instanceof State ? $value->getValue() : $value;
+    }
+
     private function getStateMapping(): Collection
     {
         return $this->baseStateClass::getStateMapping();

tests/StateCastingTest.php

@@ -136,3 +136,9 @@ public function registerStates(): void
 
     expect($model->state->getField())->toEqual('state');
 });
+
+it('serializes to a value', function() {
+    $model = new TestModel();
+
+    expect($model->toArray()['state'])->toBe(StateA::class);
+});