phpif-statementisset

PHP - what is the point of using isSet() and checking for truthy value?

I saw this in my codebase today:

if (isset($purchase_data['buyer_tracking_address_id']) && $purchase_data['buyer_tracking_address_id']) {
    // do something
}

Why would checking for both conditions be necessary? Isn't using just the first clause enough?

Solution

  • Isn't using just the first clause enough?

    Edit I see the context of your question changed while I typed this answer. I think aynber's comment answers your question.

    isset is really only there to check for the existence of the array key buyer_tracking_address_id before the the next operation tries to access it. If it doesn't exist, isset will return false and will prevent the next condition from running.

    Without isset, if you tried to access the array key buyer_tracking_address_id and it didn't exist, PHP would throw a warning.

    Warning: Undefined array key "buyer_tracking_address_id"

    The following code will throw a notice in PHP 7, and a warning in PHP 8.

    <?php

$purchase_data = [
    'buyer_tracking_address_id' => '12345'    
];

if ($purchase_data['doesnt_exist']) {
    // do something
}

    It is also worthwhile reading and understanding the ternary operator and the null coalescing operator as they are often used to access unknown array keys.