Update JsonReader to use less memory (#28)

composer.json

@@ -18,7 +18,8 @@
         "symfony/console": "^6.1",
         "symfony/filesystem": "^6.1",
         "symfony/property-access": "^6.1",
-        "symfony/serializer": "^6.1"
+        "symfony/serializer": "^6.1",
+        "halaxa/json-machine": "^1.1"
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.13",

src/Reader/JsonReader.php

@@ -13,26 +13,50 @@
 
 namespace IQ2i\DataImporter\Reader;
 
+use JsonMachine\Items;
+use JsonMachine\JsonDecoder\ExtJsonDecoder;
+
 class JsonReader implements ReaderInterface
 {
+    /**
+     * @var string
+     */
+    final public const POINTER = 'pointer';
+
     private readonly \SplFileInfo $file;
 
-    private readonly \ArrayIterator $iterator;
+    private readonly \Iterator $iterator;
 
     private int $index = 1;
 
+    private int $count = 0;
+
+    private array $defaultContext = [
+        self::POINTER => null,
+    ];
+
     public function __construct(
         string $filePath,
         private readonly ?string $dto = null,
+        array $defaultContext = [],
     ) {
         $this->file = new \SplFileInfo($filePath);
 
         if (!$this->file->isReadable()) {
             throw new \InvalidArgumentException('The file '.$this->file->getFilename().' is not readable.');
         }
 
-        $array = \json_decode(\file_get_contents($this->file->getRealPath()), true, 512, \JSON_THROW_ON_ERROR);
-        $this->iterator = new \ArrayIterator($array);
+        $this->defaultContext = \array_merge($this->defaultContext, $defaultContext);
+        $options = [
+            'decoder' => new ExtJsonDecoder(true),
+        ];
+
+        if (null !== $this->defaultContext[self::POINTER]) {
+            $options['pointer'] = $this->defaultContext[self::POINTER];
+        }
+
+        $this->count = \iterator_count(Items::fromFile($this->file->getRealPath(), $options));
+        $this->iterator = Items::fromFile($this->file->getRealPath(), $options)->getIterator();
 
         $this->rewind();
     }
@@ -89,6 +113,6 @@ public function rewind(): void
 
     public function count(): int
     {
-        return $this->iterator->count();
+        return $this->count;
     }
 }

tests/Reader/JsonReaderTest.php

@@ -22,7 +22,7 @@ public function testReadJson()
     {
         // init reader
         $reader = new JsonReader(
-            __DIR__.'/../fixtures/json/books.json',
+            __DIR__.'/../fixtures/json/books_without_pointer.json',
             null,
         );
 
@@ -31,7 +31,7 @@ public function testReadJson()
 
         // test file
         $this->assertEquals(
-            new \SplFileInfo(__DIR__.'/../fixtures/json/books.json'),
+            new \SplFileInfo(__DIR__.'/../fixtures/json/books_without_pointer.json'),
             $reader->getFile()
         );
 
@@ -79,4 +79,61 @@ public function testReadJson()
         $reader->next();
         $this->assertEquals([], $reader->current());
     }
+
+    public function testReadJsonWithPointer()
+    {
+        // init reader
+        $reader = new JsonReader(
+            __DIR__.'/../fixtures/json/books_with_pointer.json',
+            null,
+            [JsonReader::POINTER => '/author/books']
+        );
+
+        // test denormalization
+        $this->assertFalse($reader->isDenormalizable());
+
+        // test file
+        $this->assertEquals(
+            new \SplFileInfo(__DIR__.'/../fixtures/json/books_with_pointer.json'),
+            $reader->getFile()
+        );
+
+        // test count
+        $this->assertCount(2, $reader);
+
+        // test index
+        $this->assertEquals(1, $reader->index());
+        $this->assertEquals(0, $reader->key());
+
+        // test headers
+        $this->assertEquals(
+            ['title', 'genre', 'price', 'description'],
+            \array_keys($reader->current())
+        );
+        $this->assertArrayHasKey('title', $reader->current());
+        $this->assertNotNull($reader->current()['title']);
+        $this->assertArrayHasKey('genre', $reader->current());
+        $this->assertNotNull($reader->current()['genre']);
+        $this->assertArrayHasKey('price', $reader->current());
+        $this->assertNotNull($reader->current()['price']);
+        $this->assertArrayHasKey('description', $reader->current());
+        $this->assertNotNull($reader->current()['description']);
+
+        // test line
+        $reader->next();
+        $this->assertEquals(2, $reader->index());
+        $this->assertEquals(
+            [
+                'title' => 'Midnight Rain',
+                'genre' => 'Fantasy',
+                'price' => '5.95',
+                'description' => 'A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.',
+            ],
+            $reader->current()
+        );
+
+        // test and of file
+        $reader->next();
+        $this->assertEquals([], $reader->current());
+    }
 }

tests/fixtures/json/books_with_pointer.json

@@ -0,0 +1,20 @@
+{
+    "author": {
+        "firstname": "Kim",
+        "lastname": "Ralls",
+        "books": [
+            {
+                "title": "XML Developer's Guide",
+                "genre": "Computer",
+                "price": 44.95,
+                "description": "An in-depth look at creating applications with XML."
+            },
+            {
+                "title": "Midnight Rain",
+                "genre": "Fantasy",
+                "price": 5.95,
+                "description": "A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world."
+            }
+        ]
+    }
+}