Null-coalescing Operator (??)
PHP7 came with syntactic flavourings we all have been savouring ever since its release - One of which is the null-coalescing operator. If you have ever had to use the ternary
operator together with isset()
method, then this was tailor-made
for you!
$developer_status = $coding ?? $sleeping;
// is equivalent to
$developer_status = isset($coding) ? $coding : $sleeping;
It returns the first operand if true, otherwise returns the second. It is also chainable:
$developer_status = $coding ?? $sleeping ?? $eating;
Null-safe Operator (?->)
The null-safe is a PHP8 feature that, instead of throwing an exception, short-circuits to null when a chained property or method access is null and the rest of the chain is skipped.
It is an elegant
way of wrapping is_null
around each property or method access.
Let's examine the following code snippet:
$recentlyActive = null;
if (session()->has('user')) {
$user = session('user');
if (! is_null($user)) {
$lastLoggedIn = $user->lastLoggedIn();
if (! is_null($lastLoggedIn)) {
$recentlyActive = $lastLoggedIn->withinLast7Days();
}
}
}
With null-safe operator, we can be more efficient by writing less and clearer code:
$recentlyActive = session()->has('user')?->lastLoggedIn?->withinLast7Days();
Versus
What is the difference between null-safe operator and null-coalescing operator. Hint: it's not just in the syntax, it is also in the semantics.
The null-safe operator supports method while the null-coalescing operator doesn't. The null-coalescing operator supports array while the null-safe operator doesn't.
// this works
$array = [];
var_dump($array['mukulli']->kofa ?? null);
// this throws a warning
var_dump($array['mukulli']?->kofa);
// Warning: Undefined array key "key"
Null-safe with methods:
class Order
{
public function date(): ?Carbon { /* … */ }
// …
}
$order = new Order();
var_dump($order->date()?->format('Y-m-d'));
// null
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