[8.x] Allow serializing custom casts when converting a model to an array

src/Illuminate/Contracts/Database/Eloquent/SerializesCastableAttributes.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Illuminate\Contracts\Database\Eloquent;
+
+interface SerializesCastableAttributes
+{
+    /**
+     * Serialize the attribute when converting the model to an array.
+     *
+     * @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);
+}

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -240,6 +240,10 @@ protected function addCastAttributesToArray(array $attributes, array $mutatedAtt
                 $attributes[$key] = $this->serializeDate($attributes[$key]);
             }
 
+            if ($attributes[$key] && $this->isClassSerializable($key)) {
+                $attributes[$key] = $this->serializeClassCastableAttribute($key, $attributes[$key]);
+            }
+
             if ($attributes[$key] instanceof Arrayable) {
                 $attributes[$key] = $attributes[$key]->toArray();
             }
@@ -604,6 +608,19 @@ protected function getCastType($key)
         return trim(strtolower($this->getCasts()[$key]));
     }
 
+    /**
+     * Serialize the given attribute using the custom cast class.
+     *
+     * @param  string  $key
+     * @param  mixed  $value
+     * @return mixed
+     */
+    protected function serializeClassCastableAttribute($key, $value)
+    {
+        return $this->resolveCasterClass($key)
+                    ->serialize($this, $key, $value, $this->attributes);
+    }
+
     /**
      * Determine if the cast type is a custom date time cast.
      *
@@ -1090,6 +1107,24 @@ protected function isClassCastable($key)
         throw new InvalidCastException($this->getModel(), $key, $castType);
     }
 
+    /**
+     * Determine if the key is serializable using a custom class.
+     *
+     * @param  string  $key
+     * @return bool
+     * @throws InvalidCastException
+     */
+    protected function isClassSerializable($key)
+    {
+        if (! $this->isClassCastable($key)) {
+            return false;
+        }
+
+        $castType = $this->parseCasterClass($this->getCasts()[$key]);
+
+        return method_exists($castType, 'serialize');
+    }
+
     /**
      * Resolve the custom caster class for a given key.
      *

tests/Integration/Database/DatabaseEloquentModelCustomCastingTest.php

@@ -5,6 +5,7 @@
 use Illuminate\Contracts\Database\Eloquent\Castable;
 use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
 use Illuminate\Contracts\Database\Eloquent\CastsInboundAttributes;
+use Illuminate\Contracts\Database\Eloquent\SerializesCastableAttributes;
 use Illuminate\Database\Eloquent\InvalidCastException;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Carbon;
@@ -134,6 +135,24 @@ public function testGetOriginalWithCastValueObjects()
         $this->assertNull($model->address);
     }
 
+    public function testSerializableCasts()
+    {
+        $model = new TestEloquentModelWithCustomCast;
+        $model->price = '123.456';
+
+        $expectedValue = (new Decimal('123.456'))->getValue();
+
+        $this->assertSame($expectedValue, $model->price->getValue());
+        $this->assertSame('123.456', $model->getAttributes()['price']);
+        $this->assertSame('123.456', $model->toArray()['price']);
+
+        $unserializedModel = unserialize(serialize($model));
+
+        $this->assertSame($expectedValue, $unserializedModel->price->getValue());
+        $this->assertSame('123.456', $unserializedModel->getAttributes()['price']);
+        $this->assertSame('123.456', $unserializedModel->toArray()['price']);
+    }
+
     public function testOneWayCasting()
     {
         // CastsInboundAttributes is used for casting that is unidirectional... only use case I can think of is one-way hashing...
@@ -231,6 +250,7 @@ class TestEloquentModelWithCustomCast extends Model
      */
     protected $casts = [
         'address' => AddressCaster::class,
+        'price' => DecimalCaster::class,
         'password' => HashCaster::class,
         'other_password' => HashCaster::class.':md5',
         'uppercase' => UppercaseCaster::class,
@@ -306,6 +326,24 @@ public function set($model, $key, $value, $attributes)
     }
 }
 
+class DecimalCaster implements CastsAttributes, SerializesCastableAttributes
+{
+    public function get($model, $key, $value, $attributes)
+    {
+        return new Decimal($value);
+    }
+
+    public function set($model, $key, $value, $attributes)
+    {
+        return (string) $value;
+    }
+
+    public function serialize($model, $key, $value, $attributes)
+    {
+        return (string) $value;
+    }
+}
+
 class ValueObjectCaster implements CastsAttributes
 {
     private $argument;
@@ -386,6 +424,30 @@ public function __construct($lineOne, $lineTwo)
     }
 }
 
+final class Decimal
+{
+    private $value;
+    private $scale;
+
+    public function __construct($value)
+    {
+        $parts = explode('.', (string) $value);
+
+        $this->scale = strlen($parts[1]);
+        $this->value = (int) str_replace('.', '', $value);
+    }
+
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    public function __toString()
+    {
+        return substr_replace($this->value, '.', -$this->scale, 0);
+    }
+}
+
 class DateObjectCaster implements CastsAttributes
 {
     private $argument;