Question 40628 in PHP Question posted in
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Refactor array_key_exists in PHP8

Having just attempted to upgrade from PHP 7.4.33 to 8.0.27 I have encountered the following error on a key page:

Got error ‘PHP message: PHP Warning: Undefined array key 1981 in
drivers_standing_table.php on line 56

PHP message: PHP Fatal error: Uncaught TypeError: array_key_exists():
Argument #2 ($array) must be of type array, null given in
drivers_standing_table.php:56

1981 is an id (int) associated with a record in the database. For example, in this case a competitor has an id of 1981.

Line 56 of drivers_standing_table.php (and slightly thereafter) looks like this:

// LINE 56:
if (array_key_exists($round, $shared_drivers[$driver_id])) {

  $lender_id = $shared_drivers[$driver_id][$round];
  $lender_race_result = $drivers_race_result_array[$lender_id][$round][0];
  $cls_name = $drivers_race_result_array[$lender_id][$round][1];
  $race_result = $drivers_race_result_array[$driver_id][$round][0];

  if (array_key_exists($round, $drivers_race_result_array[$driver_id])) {     ?>
    <td align='center' style="background: orangered;">
        <?php echo $race_result . '/' . $lender_race_result; ?>
    </td>
  <?php
    $exit_flag = true;
    $i++;
  } else {
  ?>
    <td align='center' class='<?php echo $cls_name; ?>'>
        <?php echo $lender_race_result; ?>
    </td>
  <?php }
}

The error is preventing the script from continuing to run, breaking the page.

How should I refactor line 56 to work with PHP8?

Tags:

3

Answers


  1. 0

    You can use isset() instead, as it won’t throw an error at any nesting level:

    if (isset($shared_drivers[$driver_id][$round])) {

    Keep in mind that isset() will return false if the value is null though, but I don’t think it’s a concern in your case.

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  2. 0

    array_key_exists expect second parameter to be an array you are passing null

    First solution is to check if the second parameter is an array you can do that with is_array like that :

    if (isset($shared_drivers[$driver_id]) 
&& is_array($shared_drivers[$driver_id]) 
&& array_key_exists($round, $shared_drivers[$driver_id])) {

    Or you can use Null Coalescing Operator to change that null with empty array

    if (array_key_exists($round, $shared_drivers[$driver_id]??[])) {
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  3. 0

    You can check that the outer array key exists first and that this value is an array, stepping into the array levels through the if statement:

    if ( is_array($shared_drivers)
     && array_key_exists($driver_id, $shared_drivers) 
     && is_array($shared_drivers[$driver_id]) 
     && array_key_exists($round, $shared_drivers[$driver_id]) ){

    This means that if the $shared_drivers[$driver_id] doesn’t exist or is not an array the IF statement will abort before testing an invalid array reference ( $shared_drivers[$driver_id]) .

    If you’re certain that $shared_drivers is an array and exist at this point, you can streamline the above code by removing the first argument.

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