Improve handling of read types on custom model casts

src/Properties/ModelPropertyExtension.php

@@ -18,6 +18,7 @@
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\ShouldNotHappenException;
 use PHPStan\Type\ObjectType;
+use ReflectionNamedType;
 
 /**
  * @internal
@@ -280,7 +281,24 @@ private function castPropertiesType(Model $modelInstance): void
                     $realType = '\Illuminate\Support\Collection<array-key, mixed>';
                     break;
                 default:
-                    $realType = class_exists($type) ? ('\\'.$type) : 'mixed';
+                    if (class_exists($type)) {
+                        $realType = ('\\'.$type);
+                        $reflection = $this->reflectionProvider
+                            ->getClass($realType)
+                            ->getNativeReflection();
+                        if ($reflection->hasMethod('get')) {
+                            if ($returnType = $reflection->getMethod('get')->getReturnType()) {
+                                if ($returnType instanceof ReflectionNamedType) {
+                                    $realType = $returnType->getName();
+                                    if ($returnType->allowsNull()) {
+                                        $realType .= '|null';
+                                    }
+                                }
+                            }
+                        }
+                    } else {
+                        $realType = 'mixed';
+                    }
                     break;
             }
 

tests/Application/app/Money.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace App;
+
+class Money
+{
+    public function __construct(
+        private int $amount = 100,
+    ) {
+    }
+
+    public function getAmount(): int
+    {
+        return $this->amount;
+    }
+}

tests/Application/app/MoneyCast.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App;
+
+class MoneyCast implements \Illuminate\Contracts\Database\Eloquent\CastsAttributes {
+
+    /**
+     * @inheritDoc
+     */
+    public function get($model, string $key, $value, array $attributes): ?Money {
+        return new \App\Money($value);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function set($model, string $key, $value, array $attributes) {
+        // TODO: Implement set() method.
+    }
+}

tests/Application/app/User.php

@@ -50,6 +50,7 @@ class User extends Authenticatable
         'floatButRoundedDecimalString' => 'decimal:1',
         'options' => AsArrayObject::class,
         'properties' => AsCollection::class,
+        'balance' => MoneyCast::class,
     ];
 
     /**

tests/Application/database/migrations/2020_01_30_000000_create_users_table.php

@@ -29,6 +29,7 @@ public function up(): void
             $table->json('properties');
             $table->boolean('blocked');
             $table->unknownColumnType('unknown_column');
+            $table->integer('balance');
             $table->rememberToken();
             $table->timestamps();
             $table->softDeletes();

tests/Features/Properties/ModelPropertyExtension.php

@@ -8,6 +8,7 @@
 use App\Address;
 use App\Group;
 use App\GuardedModel;
+use App\Money;
 use App\Role;
 use App\Team;
 use App\Thread;
@@ -202,6 +203,14 @@ public function testSoftDeletesCastDateTimeAndNullable(User $user): ?string
         return $user->deleted_at?->format('d/m/Y');
     }
 
+    /** @return Money|null */
+    public function testCastClassReturnsDifferentClassInstanceOrNull(User $user)
+    {
+        assertType('App\\Money|null', $user->balance);
+
+        return $user->balance;
+    }
+
     public function testWriteToSoftDeletesColumn(): void
     {
         $this->user->deleted_at = 'test';