WordPress.org
Get WordPress

Make WordPress Core

Opened 5 weeks ago

Last modified 5 weeks ago

#59774 new defect (bug)

Undefined array key when using wp_list_pluck function

Reported by: iamarunchaitanyajami's profile iamarunchaitanyajami Owned by:
Milestone: 6.5 Priority: normal
Severity: normal Version: 5.1
Component: Script Loader Keywords: has-patch needs-unit-tests has-testing-info
Focuses: Cc:

Description

Bug Description:

Issue: When using the wp_list_pluck function to extract values from an array, a PHP warning is triggered if the specified key is not found within the array. The warning message is as follows:

PHP Warning: Undefined array key "required" in /var/www/html/wp-includes/class-wp-list-util.php on line 171

Steps to Reproduce:

  1. Use the wp_list_pluck function on an array.
  2. Specify a key that may or may not exist within the array.
  3. Observe the PHP warning generated when the key is not found.

Expected Behavior:
The wp_list_pluck function should gracefully handle cases where the specified key is not present in the array and not trigger a PHP warning.

Actual Behavior:
The function generates a PHP warning with an "Undefined array key" message, which could lead to unnecessary log clutter and confusion.

Environment:

  • WordPress version: 6.3 and Higher
  • PHP version: >= 8
  • Operating system: UBUNTU

Proposed Solution:
To handle this situation gracefully without errors, you can check if the key exists in the array before attempting to access it. You can use the isset() function to determine if the key exists. Here's how you can modify the code:

Code highlighting: 

if (is_object($value)) {
  $newlist[$key] = isset($value->$field) ? $value->$field : array();
} elseif (is_array($value)) {
  $newlist[$key] = isset($value[$field]) ? $value[$field] : array();
} else {
  _doing_it_wrong(
      __METHOD__,
      __('Values for the input array must be either objects or arrays.'),
      '6.2.0'
  );
}

In the modified code, we use isset() to check if the key $field exists in either the object or the array. If the key exists, it assigns the value to $newlist[$key]. If the key doesn't exist, it assigns empty array().

This modification will prevent the code from triggering an error when attempting to access non-existent keys in an array or object. Instead, it will gracefully assign empty array().

Attachments (1)

class-wp-list-util.php​ (7.3 KB) - added by iamarunchaitanyajami 5 weeks ago.

Download all attachments as: .zip

Change History (4)

@iamarunchaitanyajami
5 weeks ago

This ticket was mentioned in ​PR #5596 on ​WordPress/wordpress-develop by ​@iamarunchaitanyajami.
5 weeks ago #1

In this PR, we use coalescing operator ?? to check if the key $field exists in either the object or the array. If the key exists, it assigns the value to $newlist[$key]. If the key doesn't exist, it assigns empty array().
This modification will prevent the code from triggering an error when attempting to access non-existent keys in an array or object. Instead, it will gracefully assign empty array().

Trac ticket: https://core.trac.wordpress.org/ticket/59774

#2 in reply to: ↑ description @iamarunchaitanyajami
5 weeks ago

Instead of using isset we will be using coalescing operator ?? to check if the key $field exists.

So the updated code will be

Code highlighting: 

if (is_object($value)) {
  $newlist[$key] = $value->$field ?? array();
} elseif (is_array($value)) {
  $newlist[$key] = $value[ $field ] ?? array();
} else {
  _doing_it_wrong(
      __METHOD__,
      __('Values for the input array must be either objects or arrays.'),
      '6.2.0'
  );
}

Replying to iamarunchaitanyajami:

Bug Description:

Issue: When using the wp_list_pluck function to extract values from an array, a PHP warning is triggered if the specified key is not found within the array. The warning message is as follows:

PHP Warning: Undefined array key "required" in /var/www/html/wp-includes/class-wp-list-util.php on line 171

Steps to Reproduce:

  1. Use the wp_list_pluck function on an array.
  2. Specify a key that may or may not exist within the array.
  3. Observe the PHP warning generated when the key is not found.

Expected Behavior:
The wp_list_pluck function should gracefully handle cases where the specified key is not present in the array and not trigger a PHP warning.

Actual Behavior:
The function generates a PHP warning with an "Undefined array key" message, which could lead to unnecessary log clutter and confusion.

Environment:

  • WordPress version: 6.3 and Higher
  • PHP version: >= 8
  • Operating system: UBUNTU

Proposed Solution:
To handle this situation gracefully without errors, you can check if the key exists in the array before attempting to access it. You can use the isset() function to determine if the key exists. Here's how you can modify the code:

Code highlighting: 

if (is_object($value)) {
  $newlist[$key] = isset($value->$field) ? $value->$field : array();
} elseif (is_array($value)) {
  $newlist[$key] = isset($value[$field]) ? $value[$field] : array();
} else {
  _doing_it_wrong(
      __METHOD__,
      __('Values for the input array must be either objects or arrays.'),
      '6.2.0'
  );
}

In the modified code, we use isset() to check if the key $field exists in either the object or the array. If the key exists, it assigns the value to $newlist[$key]. If the key doesn't exist, it assigns empty array().

This modification will prevent the code from triggering an error when attempting to access non-existent keys in an array or object. Instead, it will gracefully assign empty array().

#3 @hellofromTonya
5 weeks ago

  • Keywords needs-unit-tests has-testing-info added
  • Milestone changed from Awaiting Review to 6.5
  • Version changed from trunk to 5.1

Hello @iamarunchaitanyajami,

Welcome to WordPress Core's Trac :) Thank you for opening this ticket.

I'm doing some ticket triage to help this ticket be in a ready state for consideration:

  • Version is the WP version that introduced the code or issue. The code in question was introduced in [42527] via #16895 during WP 5.1.
  • Moving into 6.5 for consideration.
  • Keywords:
    • Adding needs-unit-tests as tests can help to show the issue, confirm it is resolved, and help with future regressions.
    • Adding has-testing-info as you shared the steps to reproduce in the description - thank you :)
Note: See TracTickets for help on using tickets.