Discussion on: Best Practice - Check if property exist and assign

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Replies for: One way to make this shorter is to use PHP7's null coalesce operator: $i->samples = $issues['samples'] ?? null; and to make it a bit DRYe...

Personally I would move that logic inside a QualityIssue static method:

class QualityIssue {
   public static function fromArray(array $source): self
   {
      $properties = ['samples', 'summary', 'property_names', ]; // etc.
      $instance = new self();
      foreach ($properties as $property) {
         $instance->{$property} = $issues[$property] ?? null;
      }

      return $instance;
   }
}

In this way the acceptable fields are listed only inside the class that define them, and the properties could also be protected or private (* see below). And the code of the OP could simply be:

foreach($data['quality_issues']['data'] as $issue){
    if($issue['property_names'] != 'product_category'){
        $partner->catalog->quality_issues[] = QualityIssue::fromArray($issue);
    }
}

(*) because yes, you can access a private property from outside the object, if you do it from a method of that class:

class Foo {
   private $myProp = 'dog';

   public static function changeProp(Foo $foreign): void
   {
      $foreign->myProp = 'cat';
   }
}

$subject = new Foo();
Foo::changeProp($subject);

Michael Lueckl • Aug 8 '18 • Edited

I do really like this approach!
I wasn't aware you can assign property names like this and creating a static class is so much cleaner and provides a lot of benefits.

This is what I was looking for :)

Can you please explain what
: self
exactly is used for?
From what I understand it allows you to create an instance of the class inside the static method but it works also when I remove it.
I don't really know how to search for it and couldn't find an explanation.

Cheers

Franco Traversaro • Aug 8 '18

It's a PHP 7 feature, it's called "return type declaration": basically you declare that the function will always return something having the declared type; if you return something else, like an integer, or don't return anything, a TypeError is thrown. I really like this feature, strict type force you to write better code.

Michael Lueckl • Aug 9 '18 • Edited

This is great, guess most of the time I use PHP in a too "simple" way and should get more familiar with such details as it really helps to improve and ease the code :)

It's basically like in C++, or similar languages, when you define a function with a specific return type like

static QualityIssue fromArray(vector<type> &source){}

Thanks for the explanation, I struggled to find a good search query for this question with only the code.