PHP Best Practices

Am I making a mistake? Is this the right decision in the long term? Join me as I show PHP code of over 10 years. I'll explain what worked well, what didn't and why. You can then make informed decisions for the robustness and maintainability of your application. On the menu: SOLID principles, testability, dependency injection, exception handling, use of null and false, ORMs, etc.

Transcript

1. 
   PHP Best Practices
   MONTREAL | FEB 26, 2020 @afilina
   

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2. Anna Filina
   ‣ Coding since 1997.
   ‣ PHP since 2003.
   ‣ Legacy archaeologist.
   ‣ Test automation.
   ‣ Talks and workshops.
   ‣ YouTube videos.
   

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4. What Is This About?
   ‣ Not talking about nice-to-haves.
   ‣ Not talking about style.
   ‣ Real bugs as justification for each point.
   

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5. $sql = 'SELECT * FROM users WHERE email="'.$email.'"';
   $this->pdo->query($sql);
   // abc" OR 1=1 OR email="abc
   // SELECT * FROM users WHERE email="abc" OR 1=1 OR
   email="abc";
   $sql = 'SELECT * FROM users WHERE email = :email';
   $statement = $this->pdo->prepare($sql);
   $statement->execute([':email' => $email]);
   

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6. $paths = $this->getPaths();
   $urls = array_map(function ($path) {
   return self::URL_ROOT . $path;
   }, $paths);
   array_map(): Expected parameter 2 to be an array, string given
   

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7. private function getPaths()
   {
   return '[
   {"list_products":"/products"},
   {"view_cart":"/cart"},
   ]';
   }
   

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8. private function getPaths(): array
   {
   return [
   $this->path1,
   $this->path2,
   ];
   }
   

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9. $paths = $this->getPaths();
   $urls = array_map(function ($path) {
   return self::URL_ROOT . $path;
   }, $paths);
   Array to string conversion
   

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10. private $path1 = ['list_products' => '/products'];
    private $path2 = ['view_cart' => '/cart'];
    

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11. private $path1 = '/products';
    private $path2 = '/cart';
    

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12. $urls = array_map(function (string $path) {
    return self::URL_ROOT . $path;
    }, $paths);
    

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13. /**
    * @return array
    */
    private function getPaths(): array
    

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14. composer require --dev vimeo/psalm
    vendor/bin/psalm --init
    Detected level 7 as a suitable initial default
    vendor/bin/psalm src
    

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15. /**
    * @return array
    */
    private function getPaths(): array
    ERROR: MixedReturnTypeCoercion - src/TypeMismatch.php:65:16 - The
    type 'array{0: mixed, 1: mixed}' is more general than the declared return
    type 'array' ...
    

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16. if ($path === '') {
    throw new InvalidArgumentException('Is blank');
    }
    

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17. function (Path $path) {
    return self::URL_ROOT . $path;
    }, $paths);
    

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18. final class Path
    {
    private string $path;
    public function __construct(string $path)
    {
    Assert::that($path)
    ->notBlank();
    $this->path = $path;
    }
    public function __toString(): string
    {
    return $this->path;
    }
    }
    

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19. array_map(function (Path $path) {
    return self::URL_ROOT . $path;
    }, $paths);
    

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20. /**
    * @return array
    */
    private function getPaths(): array
    {
    return [
    new Path('/products'),
    new Path('/cart'),
    ];
    }
    

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21. public function setPrice(int $price)
    {
    $this->price = $price;
    }
    $this->setPrice(1.15);
    

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22. declare(strict_types=1);
    TypeError : Argument 1 passed to MyClass::setPrice() must be of the
    type int, float given
    

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23. Strict types.

    Strict types.
    Strict types.
    

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24. private string $stringPath;
    private Path $voPath;
    

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25. NPEs galore.
    

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26. class Product
    {
    public $name;
    }
    //...
    $this->findByName($this->product->name);
    

    TypeError : Argument 1 passed to MyClass::findByName()
    must be of the type string, null given
    

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27. class Product
    {
    public string $name;
    }
    

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28. class ProductEntity
    {
    public $name;

    public $price;
    }
    final class Product
    {
    public string $name;
    public int $price;
    //...
    }
    

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29. return new Product(
    $product->name,
    $product->price
    );
    

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30. if ($product->getLastPrice() !== null) {
    return number_format($product->getLastPrice());
    }
    TypeError : number_format() expects parameter 1 to be
    float, null given
    

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31. public function getLastPrice()
    {
    return array_pop($this->prices);
    }
    

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32. $lastPrice = $product->getLastPrice();
    if ($lastPrice !== null) {
    return number_format($lastPrice);
    }
    

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33. @$array[$foo->a()];
    public function a()
    {
    trigger_error('my error', E_USER_ERROR);
    }
    $array[$foo->a()] ?? 'something else';
    

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34. interface ApiAware
    {
    public function setApi(Api $api);
    }
    if ($class instanceof ApiAware) {
    $class->setApi($api);
    }
    

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35. final class MyClass implements ApiAware
    {
    private $api;
    public function setApi(Api $api): void
    {
    $this->api = $api;
    }
    public function sendApiRequest()
    {
    $product = new Product();
    $this->api->sendRequest($product);
    }
    }
    

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36. Error : Call to a member function sendRequest() on null
    

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37. final class MyClass
    {
    private Api $api;
    public function __construct(Api $api)
    {
    $this->api = $api;
    }
    public function sendApiRequest()
    {
    $product = new Product();
    $this->api->sendRequest($product);
    }
    }
    

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38. Dependency injection 

    is your friend.
    

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39. if (!empty($array)) {
    return $array[0];
    }
    Trying to access array offset on value of type bool
    

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40. if (empty($airplaneSeat)) {
    $this->book($airplaneSeat);
    }
    

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41. empty("");
    empty(0);
    empty(0.0);
    empty("0");
    empty(null);
    empty(false);
    empty(array());
    

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42. !== ""
    !== 0
    !== 0.0
    !== null
    === true
    count(array())
    

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43. 0.99 + 0.01 === 1
    

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44. IEEE 754

    floating point arithmetic.
    

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45. $amountInCents + 1
    

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46. /** @var PaymentGatewayInterface */
    $gateway = $this->getSelectedGateway();
    $gateway->preauthorizePayment();
    

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47. How to test?
    

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48. $soapApi = new SoapApi($wsdl, $soapKey, $config);
    public function __construct(SoapApi $soap)
    {
    $this->soap = $soap;
    }
    

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49. class Order
    {
    public function getProducts()
    {
    return Product::find($this->productIds);
    }
    }
    Product::shouldReceive('find')
    ->once()
    ->andReturn([]);
    

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50. class MyController extends AbstractController
    {
    public function myAction()
    {
    $doctrine = $this->container->get('doctrine');
    }
    }
    

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51. Dependency injection 

    is your friend.
    

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52. 
    THANKS!
    @afilina
    

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