PHP 7: Type-safe Arrays of Objects

With PHP 7 you can choose to write much more type-safe code than before, thanks to scalar type hints and return types.

function repeat(string $text, int $times) : string;

But what about arrays? There’s still only the generic “array” type hint, you cannot specify what’s in the array. For the IDE, you can add PhpDoc comments:

/**
 * @return User[]
 */
function allUsers() : array;

Now IDEs like PhpStorm can help with code completion for items in the returned array. But we cannot benefit from any checks at runtime, like with real type hints.

For arguments, there is a partial workaround, using variadic arguments. Take the following function

/**
 * @param User[] $users
 */
function deleteUsers(array $users);

With variadic arguments we can rewrite it to

function deleteUsers(User ...$users);

Usage also changes, to deleteUsers(...$users); In this call, the argument $users will be “unpacked” into single variables, and in the method itself “packed” back into an array $users. Each item is validated to be of type User. $users can also be an iterator, it will be converted to an array.

Unfortunately there is no similar workaround for return types, and it only works for the last argument.

See also: Type hinting in PHP 7 – array of objects

I’ve used this technique a lot in PHP 7 code, but I’ve found another one that’s even better and does not come with the mentioned flaws:
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PHPUnit, PhpStorm and docker-compose

I wanted to run tests with PHPUnit on a docker environment, which was set up with docker-compose, and use the PhpStorm integration. Since PhpStorm 2013.2 there is a docker intergration which works well for single containers, but unfortunately it does not seem to use the running network of containers. So for example my PHP container does not get access to the MySQL container for integration tests.

If that’s not a problem for you, you will not need what I am going to explain here, read this instead: https://blog.jetbrains.com/phpstorm/2016/11/docker-remote-interpreters/

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Sensible Namespaces in PHP

Common convention for namespaces in PHP is to start with Vendor\Package, capitalized (CamelCase StudlyCaps) with “vendor” and “package” analogous to the composer package name.

There is a bad habit I see often, probably coming from the ZF1 and Pear days, where every word in the class name is a new sub namespace (and a new subdirectory), or child classes are moved into a namespace with the name of the parent class. All this is leading to deeply nested namespaces and class names that have no meaning without their namespace.

Examples from Zend Framework 1 (pseudo namespaces):

  • Zend_Db_Table_Row_Abstract an abstract base class for Zend_Db_Table_Row, representing a database table row. There are also Zend_Db_Table and Zend_Db.
  • Zend_Pdf_FileParser_Font_OpenType_TrueType a parser for true type font files. The class extends Zend_Pdf_FileParser_Font_OpenType which extends Zend_Pdf_FileParser_Font which extends Zend_Pdf_FileParser

And a current example from Magento 2:

  • Magento\Catalog\Model\Product\Option\Type\File\Validator – A validator for product options of the type “file”

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Collection Pipelines in PHP

If you read the book “Refactoring to Collections” or saw screencasts and talks by Adam Wathan about collection pipelines, but do not work with Laravel, you might have asked yourself how to apply these techniques to other PHP applications, for example Magento.

If you did not, let me explain collection pipelines first. Better, I’ll let Martin Fowler give the definition:

A collection pipeline lays out a sequence of operations that pass a collection of items between them. Each operation takes a collection as an input and emits another collection (except the last operation, which may be a terminal that emits a single value). The individual operations are simple, but you can create complex behavior by stringing together the various operations, much as you might plug pipes together in the physical world, hence the pipeline metaphor.

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What to mock in a Magento 2 unit test

You write unit tests for a Magento 2 module and need to mock a core class, like the store model. This class has a few dependencies which have more dependencies and it’s getting complicated to mock. Although PHPUnit 5.4 has a createMock() method that automatically stubs methods and let them return new stubs if they have a return type.

Or: you mock a service contract like getList() in the product repository, which takes a search criteria instance as parameter, which must be returned by a search criteria factory. Then it returns a product search result, which has a getItems() method, which returns a array of products. So you end up mocking countless dependendencies for a single method call

Do these situations sound familiar? It does not need to be like that, though! Let me show you a sane way to deal with Magento dependencies.

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Learn Refactoring to Framework Independent Code

I’m proud to annouce that I will present the Nomad Mage session of January 2017. Nomad Mage is the Magento offspring of Nomad PHP and describes itself as:

Nomad Mage® is a virtual user group for Magento developers who understand that they need to keep learning to grow professionally. We meet online monthly to hear some of the best speakers in the community share what they’ve learned.

My topic: “Keep Magento Out of Your Magento Extensions – Refactoring to Framework Independent Code”

To port an existing Magento 1 extension to Magento 2, it can be helpful to first extract the business logic into a reusable library. This also makes for more testable and future-proof code. But how can it be done?

On Nomad Mage I’m going to walk through real examples to show you how such a refactoring can be approached. Although we will focus on refactoring existing Magento 1 extensions, the patterns you will learn are also useful for new extensions, Magento 1 or Magento 2.

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PDF Generation in Magento 2

magento-pdf-layout

The Magento core methods to generate PDF files are rather unflexible. An alternative are tools that convert HTML to PDF.

In our current Magento 2 project, which we (integer_net) develop together with Stämpfli AG, there is a requirement to dynamically create a PDF catalog based on selected products, which has almost the same layout as the product lists in the shop. So, generating this PDF based on HTML suggested itself.

In this article I present our solution, which integrates wkhtmltopdf with the Magento layout. At the end you will find a link to the base module on Github.

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Stop using Helpers

“Helpers” are often used as convenient collection of functions. They are also a sign of bad design, and I want you to stop writing them. I’ll quote myself

In general, having classes named “Helper”, “Util” or similar just says “I have some functions that I don’t know where to put” and don’t make much sense as a class.

It’s not very object oriented. Not at all to be frank. The idea of object oriented programming is that there are objects that send each others messages. They have an active role in the system and are not just containers for data and code, which would be a very procedural way to see them.

So what would be the role of a helper? A butler maybe, that does not act on its own and will do anything you tell him. But to do that, he needs access to your whole household, your bank account and your car.

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Memoize Method Calls in PHP with Cache Decorators

A “memoized” function is a function that only calculates the return value for each combination of arguments once and returns the previously calculated value if the function is called a second time with the same arguments.

In PHP, I often see this implemented with code like this:

class ProductRepository implements ProductRepositoryInterface
{
    private $products = [];
    public function product($id)
    {
        if (! isset($this->products[$id])) {
            $this->products[$id] = $this->load($id);
        }
        return $this->products[$id];
    }

    private function load($id) { ... }
}

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