diff --git a/test/Dto/Book.php b/test/Dto/Book.php
new file mode 100644
index 00000000..ae18d3a3
--- /dev/null
+++ b/test/Dto/Book.php
@@ -0,0 +1,22 @@
+<?php namespace League\Fractal\Test\Dto;
+
+class Book
+{
+    public $title;
+    public $year;
+    public $author;
+    public $meta;
+
+    public function __construct($title, $year, Person $author = null, array $meta = null)
+    {
+        $this->title = $title;
+        $this->year = $year;
+        $this->author = $author;
+        $this->meta = $meta;
+    }
+
+    public static function make($title, $year, Person $author = null, array $meta = null)
+    {
+        return new self($title, $year, $author, $meta);
+    }
+}
diff --git a/test/Dto/Person.php b/test/Dto/Person.php
new file mode 100644
index 00000000..b06dddee
--- /dev/null
+++ b/test/Dto/Person.php
@@ -0,0 +1,18 @@
+<?php namespace League\Fractal\Test\Dto;
+
+class Person
+{
+    public $name;
+    public $meta;
+
+    public function __construct($name, array $meta = null)
+    {
+        $this->name = $name;
+        $this->meta = $meta;
+    }
+
+    public static function make($name, array $meta = null)
+    {
+        return new self($name, $meta);
+    }
+}
diff --git a/test/ScopeTest.php b/test/ScopeTest.php
index 3a3cd227..35151de1 100755
--- a/test/ScopeTest.php
+++ b/test/ScopeTest.php
@@ -503,7 +503,7 @@ public function testDefaultIncludeSuccess()
         $expected = [
             'a' => 'b',
             'author' => [
-                'c' => 'd',
+                'name' => 'Robert Cecil Martin',
             ],
         ];
 
diff --git a/test/Serializer/ArraySerializerTest.php b/test/Serializer/ArraySerializerTest.php
index 72d8994b..b6629504 100644
--- a/test/Serializer/ArraySerializerTest.php
+++ b/test/Serializer/ArraySerializerTest.php
@@ -6,36 +6,31 @@
 use League\Fractal\Resource\NullResource;
 use League\Fractal\Scope;
 use League\Fractal\Serializer\ArraySerializer;
+use League\Fractal\Test\Dto\Person;
+use League\Fractal\Test\Dto\Book;
 use League\Fractal\Test\Stub\Transformer\GenericBookTransformer;
 use Mockery;
 use PHPUnit\Framework\TestCase;
 
 class ArraySerializerTest extends TestCase
 {
-    private $bookItemInput = [
-        'title' => 'Foo',
-        'year' => '1991',
-        '_author' => [
-            'name' => 'Dave',
-        ],
-    ];
-
-    private $bookCollectionInput = [
-        [
-            'title' => 'Foo',
-            'year' => '1991',
-            '_author' => [
-                'name' => 'Dave',
-            ],
-        ],
-        [
-            'title' => 'Bar',
-            'year' => '1997',
-            '_author' => [
-                'name' => 'Bob',
-            ],
-        ],
-    ];
+    private function bookItemInput()
+    {
+        $author = Person::make('Miguel de Cervantes');
+
+        return Book::make('Don Quixote', '1605', $author);
+    }
+
+    private function bookCollectionInput()
+    {
+        $phil = Person::make('Miguel de Cervantes');
+        $taylor = Person::make('J. K. Rowling');
+
+        return [
+            Book::make('Don Quixote', '1605', $phil),
+            Book::make('Harry Potter', '1997', $taylor)
+        ];
+    }
 
     public function testSerializingItemResource()
     {
@@ -43,16 +38,16 @@ public function testSerializingItemResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new ArraySerializer());
 
-        $resource = new Item($this->bookItemInput, new GenericBookTransformer(), 'book');
+        $resource = new Item($this->bookItemInput(), new GenericBookTransformer(), 'book');
 
         // Try without metadata
         $scope = new Scope($manager, $resource);
 
         $expected = [
-            'title' => 'Foo',
-            'year' => 1991,
+            'title' => 'Don Quixote',
+            'year' => 1605,
             'author' => [
-                'name' => 'Dave',
+                'name' => 'Miguel de Cervantes',
             ],
         ];
 
@@ -60,23 +55,23 @@ public function testSerializingItemResource()
 
         //Test single field
         $manager->parseFieldsets(['book' => 'title']);
-        $expected = ['title' => 'Foo'];
+        $expected = ['title' => 'Don Quixote'];
         $this->assertSame($expected, $scope->toArray());
 
         //Test multiple field
         $manager->parseFieldsets(['book' => 'title,year']);
         $expected = [
-            'title' => 'Foo',
-            'year' => 1991
+            'title' => 'Don Quixote',
+            'year' => 1605
         ];
         $this->assertSame($expected, $scope->toArray());
 
         //Test with relationship field
         $manager->parseFieldsets(['book' => 'title,author', 'author' => 'name']);
         $expected = [
-            'title' => 'Foo',
+            'title' => 'Don Quixote',
             'author' => [
-                'name' => 'Dave'
+                'name' => 'Miguel de Cervantes'
             ],
         ];
         $this->assertSame($expected, $scope->toArray());
@@ -89,10 +84,10 @@ public function testSerializingItemResource()
         $scope = new Scope($manager, $resource);
 
         $expected = [
-            'title' => 'Foo',
-            'year' => 1991,
+            'title' => 'Don Quixote',
+            'year' => 1605,
             'author' => [
-                'name' => 'Dave'
+                'name' => 'Miguel de Cervantes'
             ],
             'meta' => [
                 'foo' => 'bar'
@@ -104,9 +99,9 @@ public function testSerializingItemResource()
         //Test with relationship field
         $manager->parseFieldsets(['book' => 'title,author', 'author' => 'name']);
         $expected = [
-            'title' => 'Foo',
+            'title' => 'Don Quixote',
             'author' => [
-                'name' => 'Dave',
+                'name' => 'Miguel de Cervantes',
             ],
             'meta' => [
                 'foo' => 'bar',
@@ -121,7 +116,7 @@ public function testSerializingCollectionResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new ArraySerializer());
 
-        $resource = new Collection($this->bookCollectionInput, new GenericBookTransformer(), 'books');
+        $resource = new Collection($this->bookCollectionInput(), new GenericBookTransformer(), 'books');
 
         // Try without metadata
         $scope = new Scope($manager, $resource);
@@ -129,17 +124,17 @@ public function testSerializingCollectionResource()
         $expected = [
             'books' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991,
+                    'title' => 'Don Quixote',
+                    'year' => 1605,
                     'author' => [
-                        'name' => 'Dave',
+                        'name' => 'Miguel de Cervantes',
                     ],
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997,
                     'author' => [
-                        'name' => 'Bob',
+                        'name' => 'J. K. Rowling',
                     ],
                 ],
             ],
@@ -148,15 +143,15 @@ public function testSerializingCollectionResource()
         $this->assertSame($expected, $scope->toArray());
 
         // JSON array of JSON objects
-        $expectedJson = '{"books":[{"title":"Foo","year":1991,"author":{"name":"Dave"}},{"title":"Bar","year":1997,"author":{"name":"Bob"}}]}';
+        $expectedJson = '{"books":[{"title":"Don Quixote","year":1605,"author":{"name":"Miguel de Cervantes"}},{"title":"Harry Potter","year":1997,"author":{"name":"J. K. Rowling"}}]}';
         $this->assertSame($expectedJson, $scope->toJson());
 
         //Test single field
         $manager->parseFieldsets(['books' => 'title']);
         $expected = [
             'books' => [
-                ['title' => 'Foo'],
-                ['title' => 'Bar']
+                ['title' => 'Don Quixote'],
+                ['title' => 'Harry Potter']
             ]
         ];
         $this->assertSame($expected, $scope->toArray());
@@ -166,11 +161,11 @@ public function testSerializingCollectionResource()
         $expected = [
             'books' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991
+                    'title' => 'Don Quixote',
+                    'year' => 1605
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997
                 ]
             ]
@@ -182,15 +177,15 @@ public function testSerializingCollectionResource()
         $expected = [
             'books' => [
                 [
-                    'title' => 'Foo',
+                    'title' => 'Don Quixote',
                     'author' => [
-                        'name' => 'Dave'
+                        'name' => 'Miguel de Cervantes'
                     ]
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'author' => [
-                        'name' => 'Bob'
+                        'name' => 'J. K. Rowling'
                     ]
                 ]
             ]
@@ -208,17 +203,17 @@ public function testSerializingCollectionResource()
         $expected = [
             'books' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991,
+                    'title' => 'Don Quixote',
+                    'year' => 1605,
                     'author' => [
-                        'name' => 'Dave',
+                        'name' => 'Miguel de Cervantes',
                     ],
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997,
                     'author' => [
-                        'name' => 'Bob',
+                        'name' => 'J. K. Rowling',
                     ],
                 ],
             ],
@@ -229,22 +224,22 @@ public function testSerializingCollectionResource()
 
         $this->assertSame($expected, $scope->toArray());
 
-        $expectedJson = '{"books":[{"title":"Foo","year":1991,"author":{"name":"Dave"}},{"title":"Bar","year":1997,"author":{"name":"Bob"}}],"meta":{"foo":"bar"}}';
+        $expectedJson = '{"books":[{"title":"Don Quixote","year":1605,"author":{"name":"Miguel de Cervantes"}},{"title":"Harry Potter","year":1997,"author":{"name":"J. K. Rowling"}}],"meta":{"foo":"bar"}}';
         $this->assertSame($expectedJson, $scope->toJson());
 
         $manager->parseFieldsets(['books' => 'title,author', 'author' => 'name']);
         $expected = [
             'books' => [
                 [
-                    'title' => 'Foo',
+                    'title' => 'Don Quixote',
                     'author' => [
-                        'name' => 'Dave'
+                        'name' => 'Miguel de Cervantes'
                     ]
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'author' => [
-                        'name' => 'Bob'
+                        'name' => 'J. K. Rowling'
                     ]
                 ]
             ],
@@ -261,7 +256,7 @@ public function testSerializingNullResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new ArraySerializer());
 
-        $resource = new NullResource($this->bookCollectionInput, new GenericBookTransformer(), 'books');
+        $resource = new NullResource($this->bookCollectionInput(), new GenericBookTransformer(), 'books');
 
         // Try without metadata
         $scope = new Scope($manager, $resource);
@@ -313,13 +308,13 @@ public function testSerializingCollectionResourceWithoutName()
         $manager->parseIncludes('author');
         $manager->setSerializer(new ArraySerializer());
 
-        $resource = new Collection($this->bookCollectionInput, new GenericBookTransformer());
+        $resource = new Collection($this->bookCollectionInput(), new GenericBookTransformer());
 
         // Try without metadata
         $scope = new Scope($manager, $resource);
 
         // JSON array of JSON objects
-        $expectedJson = '{"data":[{"title":"Foo","year":1991,"author":{"name":"Dave"}},{"title":"Bar","year":1997,"author":{"name":"Bob"}}]}';
+        $expectedJson = '{"data":[{"title":"Don Quixote","year":1605,"author":{"name":"Miguel de Cervantes"}},{"title":"Harry Potter","year":1997,"author":{"name":"J. K. Rowling"}}]}';
         $this->assertSame($expectedJson, $scope->toJson());
 
         // Same again with metadata
@@ -327,7 +322,7 @@ public function testSerializingCollectionResourceWithoutName()
 
         $scope = new Scope($manager, $resource);
 
-        $expectedJson = '{"data":[{"title":"Foo","year":1991,"author":{"name":"Dave"}},{"title":"Bar","year":1997,"author":{"name":"Bob"}}],"meta":{"foo":"bar"}}';
+        $expectedJson = '{"data":[{"title":"Don Quixote","year":1605,"author":{"name":"Miguel de Cervantes"}},{"title":"Harry Potter","year":1997,"author":{"name":"J. K. Rowling"}}],"meta":{"foo":"bar"}}';
         $this->assertSame($expectedJson, $scope->toJson());
     }
 
diff --git a/test/Serializer/DataArraySerializerTest.php b/test/Serializer/DataArraySerializerTest.php
index 948aa40f..7037671a 100644
--- a/test/Serializer/DataArraySerializerTest.php
+++ b/test/Serializer/DataArraySerializerTest.php
@@ -6,6 +6,8 @@
 use League\Fractal\Resource\NullResource;
 use League\Fractal\Scope;
 use League\Fractal\Serializer\DataArraySerializer;
+use League\Fractal\Test\Dto\Person;
+use League\Fractal\Test\Dto\Book;
 use League\Fractal\Test\Stub\Transformer\GenericBookTransformer;
 use Mockery;
 use PHPUnit\Framework\TestCase;
@@ -18,13 +20,8 @@ public function testSerializingItemResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new DataArraySerializer());
 
-        $bookData = [
-            'title' => 'Foo',
-            'year' => '1991',
-            '_author' => [
-                'name' => 'Dave',
-            ],
-        ];
+        $phil = Person::make('Miguel de Cervantes');
+        $bookData = Book::make('Don Quixote', '1605', $phil);
 
         // Try without metadata
         $resource = new Item($bookData, new GenericBookTransformer(), 'book');
@@ -32,11 +29,11 @@ public function testSerializingItemResource()
 
         $expected = [
             'data' => [
-                'title' => 'Foo',
-                'year' => 1991,
+                'title' => 'Don Quixote',
+                'year' => 1605,
                 'author' => [
                     'data' => [
-                        'name' => 'Dave',
+                        'name' => 'Miguel de Cervantes',
                     ],
                 ],
             ],
@@ -48,7 +45,7 @@ public function testSerializingItemResource()
         $manager->parseFieldsets(['book' => 'title']);
         $expected = [
             'data' => [
-                'title' => 'Foo',
+                'title' => 'Don Quixote',
             ]
         ];
         $this->assertSame($expected, $scope->toArray());
@@ -57,8 +54,8 @@ public function testSerializingItemResource()
         $manager->parseFieldsets(['book' => 'title,year']);
         $expected = [
             'data' => [
-                'title' => 'Foo',
-                'year' => 1991
+                'title' => 'Don Quixote',
+                'year' => 1605
             ]
         ];
         $this->assertSame($expected, $scope->toArray());
@@ -67,10 +64,10 @@ public function testSerializingItemResource()
         $manager->parseFieldsets(['book' => 'title,author', 'author' => 'name']);
         $expected = [
             'data' => [
-                'title' => 'Foo',
+                'title' => 'Don Quixote',
                 'author' => [
                     'data' => [
-                        'name' => 'Dave'
+                        'name' => 'Miguel de Cervantes'
                     ]
                 ]
             ]
@@ -88,12 +85,11 @@ public function testSerializingItemResource()
 
         $expected = [
             'data' => [
-                'title' => 'Foo',
-                'year' => 1991,
+                'title' => 'Don Quixote',
+                'year' => 1605,
                 'author' => [
                     'data' => [
-                        'name' => 'Dave',
-
+                        'name' => 'Miguel de Cervantes',
                     ],
                 ],
             ],
@@ -108,11 +104,10 @@ public function testSerializingItemResource()
         $manager->parseFieldsets(['book' => 'title,author', 'author' => 'name']);
         $expected = [
             'data' => [
-                'title' => 'Foo',
+                'title' => 'Don Quixote',
                 'author' => [
                     'data' => [
-                        'name' => 'Dave'
-
+                        'name' => 'Miguel de Cervantes',
                     ]
                 ]
             ],
@@ -129,21 +124,15 @@ public function testSerializingCollectionResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new DataArraySerializer());
 
+        $phil = Person::make('Miguel de Cervantes');
+        $bookFoo = Book::make('Don Quixote', '1605', $phil);
+
+        $taylor = Person::make('J. K. Rowling');
+        $bookBar = Book::make('Harry Potter', '1997', $taylor);
+
         $booksData = [
-            [
-                'title' => 'Foo',
-                'year' => '1991',
-                '_author' => [
-                    'name' => 'Dave',
-                ],
-            ],
-            [
-                'title' => 'Bar',
-                'year' => '1997',
-                '_author' => [
-                    'name' => 'Bob',
-                ],
-            ],
+            $bookFoo,
+            $bookBar,
         ];
 
         // Try without metadata
@@ -154,20 +143,20 @@ public function testSerializingCollectionResource()
         $expected = [
             'data' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991,
+                    'title' => 'Don Quixote',
+                    'year' => 1605,
                     'author' => [
                         'data' => [
-                            'name' => 'Dave',
+                            'name' => 'Miguel de Cervantes',
                         ],
                     ],
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997,
                     'author' => [
                         'data' => [
-                            'name' => 'Bob',
+                            'name' => 'J. K. Rowling',
                         ],
                     ],
                 ],
@@ -176,15 +165,15 @@ public function testSerializingCollectionResource()
 
         $this->assertSame($expected, $scope->toArray());
 
-        $expectedJson = '{"data":[{"title":"Foo","year":1991,"author":{"data":{"name":"Dave"}}},{"title":"Bar","year":1997,"author":{"data":{"name":"Bob"}}}]}';
+        $expectedJson = '{"data":[{"title":"Don Quixote","year":1605,"author":{"data":{"name":"Miguel de Cervantes"}}},{"title":"Harry Potter","year":1997,"author":{"data":{"name":"J. K. Rowling"}}}]}';
         $this->assertSame($expectedJson, $scope->toJson());
 
         //Test single field
         $manager->parseFieldsets(['books' => 'title']);
         $expected = [
             'data' => [
-                ['title' => 'Foo'],
-                ['title' => 'Bar']
+                ['title' => 'Don Quixote'],
+                ['title' => 'Harry Potter'],
             ],
         ];
         $this->assertSame($expected, $scope->toArray());
@@ -194,11 +183,11 @@ public function testSerializingCollectionResource()
         $expected = [
             'data' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991
+                    'title' => 'Don Quixote',
+                    'year' => 1605
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997
                 ]
             ],
@@ -210,18 +199,18 @@ public function testSerializingCollectionResource()
         $expected = [
             'data' => [
                 [
-                    'title' => 'Foo',
+                    'title' => 'Don Quixote',
                     'author' => [
                         'data' => [
-                            'name' => 'Dave'
+                            'name' => 'Miguel de Cervantes',
                         ]
                     ]
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'author' => [
                         'data' => [
-                            'name' => 'Bob'
+                            'name' => 'J. K. Rowling',
                         ]
                     ]
                 ]
@@ -242,20 +231,20 @@ public function testSerializingCollectionResource()
         $expected = [
             'data' => [
                 [
-                    'title' => 'Foo',
-                    'year' => 1991,
+                    'title' => 'Don Quixote',
+                    'year' => 1605,
                     'author' => [
                         'data' => [
-                            'name' => 'Dave',
+                            'name' => 'Miguel de Cervantes',
                         ],
                     ],
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'year' => 1997,
                     'author' => [
                         'data' => [
-                            'name' => 'Bob',
+                            'name' => 'J. K. Rowling',
                         ],
                     ],
                 ],
@@ -267,31 +256,31 @@ public function testSerializingCollectionResource()
 
         $this->assertSame($expected, $scope->toArray());
 
-        $expectedJson = '{"data":[{"title":"Foo","year":1991,"author":{"data":{"name":"Dave"}}},{"title":"Bar","year":1997,"author":{"data":{"name":"Bob"}}}],"meta":{"foo":"bar"}}';
+        $expectedJson = '{"data":[{"title":"Don Quixote","year":1605,"author":{"data":{"name":"Miguel de Cervantes"}}},{"title":"Harry Potter","year":1997,"author":{"data":{"name":"J. K. Rowling"}}}],"meta":{"foo":"bar"}}';
         $this->assertSame($expectedJson, $scope->toJson());
 
         $manager->parseFieldsets(['books' => 'title,author', 'author' => 'name']);
         $expected = [
             'data' => [
                 [
-                    'title' => 'Foo',
+                    'title' => 'Don Quixote',
                     'author' => [
                         'data' => [
-                            'name' => 'Dave'
+                            'name' => 'Miguel de Cervantes',
                         ]
                     ]
                 ],
                 [
-                    'title' => 'Bar',
+                    'title' => 'Harry Potter',
                     'author' => [
                         'data' => [
-                            'name' => 'Bob'
+                            'name' => 'J. K. Rowling',
                         ]
                     ]
                 ]
             ],
             'meta' => [
-                'foo' => 'bar'
+                'foo' => 'bar',
             ]
         ];
 
@@ -304,13 +293,8 @@ public function testSerializingNullResource()
         $manager->parseIncludes('author');
         $manager->setSerializer(new DataArraySerializer());
 
-        $bookData = [
-            'title' => 'Foo',
-            'year' => '1991',
-            '_author' => [
-                'name' => 'Dave',
-            ],
-        ];
+        $phil = Person::make('Miguel de Cervantes');
+        $bookData = Book::make('Don Quixote', '1605', $phil);
 
         // Try without metadata
         $resource = new NullResource($bookData, new GenericBookTransformer(), 'book');
diff --git a/test/Stub/Transformer/DefaultIncludeBookTransformer.php b/test/Stub/Transformer/DefaultIncludeBookTransformer.php
index be85b8f6..97a60410 100644
--- a/test/Stub/Transformer/DefaultIncludeBookTransformer.php
+++ b/test/Stub/Transformer/DefaultIncludeBookTransformer.php
@@ -1,5 +1,6 @@
 <?php namespace League\Fractal\Test\Stub\Transformer;
 
+use League\Fractal\Test\Dto\Person;
 use League\Fractal\TransformerAbstract;
 
 class DefaultIncludeBookTransformer extends TransformerAbstract
@@ -15,6 +16,6 @@ public function transform()
 
     public function includeAuthor()
     {
-        return $this->item(['c' => 'd'], new GenericAuthorTransformer());
+        return $this->item(Person::make('Robert Cecil Martin'), new GenericAuthorTransformer());
     }
 }
diff --git a/test/Stub/Transformer/GenericAuthorTransformer.php b/test/Stub/Transformer/GenericAuthorTransformer.php
index 1885f8c9..faa8ba47 100644
--- a/test/Stub/Transformer/GenericAuthorTransformer.php
+++ b/test/Stub/Transformer/GenericAuthorTransformer.php
@@ -1,11 +1,14 @@
 <?php namespace League\Fractal\Test\Stub\Transformer;
 
+use League\Fractal\Test\Dto\Person;
 use League\Fractal\TransformerAbstract;
 
 class GenericAuthorTransformer extends TransformerAbstract
 {
-    public function transform(array $author)
+    public function transform(Person $author)
     {
-        return $author;
+        return [
+            'name' => $author->name,
+        ];
     }
 }
diff --git a/test/Stub/Transformer/GenericBookTransformer.php b/test/Stub/Transformer/GenericBookTransformer.php
index 633ed508..5d92aab0 100644
--- a/test/Stub/Transformer/GenericBookTransformer.php
+++ b/test/Stub/Transformer/GenericBookTransformer.php
@@ -1,5 +1,6 @@
 <?php namespace League\Fractal\Test\Stub\Transformer;
 
+use League\Fractal\Test\Dto\Book;
 use League\Fractal\TransformerAbstract;
 
 class GenericBookTransformer extends TransformerAbstract
@@ -8,20 +9,26 @@ class GenericBookTransformer extends TransformerAbstract
         'author',
     ];
 
-    public function transform(array $book)
+    public function transform(Book $book)
     {
-        $book['year'] = (int) $book['year'];
-        unset($book['_author']);
+        $data = [
+            'title' => $book->title,
+            'year' => (int) $book->year,
+        ];
 
-        return $book;
+        if (! is_null($book->meta)) {
+            $data['meta'] = $book->meta;
+        }
+
+        return $data;
     }
 
-    public function includeAuthor(array $book)
+    public function includeAuthor(Book $book)
     {
-        if (! isset($book['_author'])) {
+        if (is_null($book->author)) {
             return;
         }
 
-        return $this->item($book['_author'], new GenericAuthorTransformer(), 'author');
+        return $this->item($book->author, new GenericAuthorTransformer(), 'author');
     }
 }