[wp-trac] [WordPress Trac] #59774: Undefined array key when using wp_list_pluck function

[WordPress Trac]

#59774: Undefined array key when using wp_list_pluck function
----------------------------------+------------------------------
 Reporter:  iamarunchaitanyajami  |       Owner:  (none)
     Type:  defect (bug)          |      Status:  new
 Priority:  normal                |   Milestone:  Awaiting Review
Component:  Script Loader         |     Version:  trunk
 Severity:  normal                |  Resolution:
 Keywords:  has-patch             |     Focuses:
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Comment (by iamarunchaitanyajami):

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

 So the updated code will be

 > {{{
 > #!div style="font-size: 80%"
 > Code highlighting:
 >   {{{#!php
 >   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 [ticket:59774 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:
 >
 > {{{
 > #!div style="font-size: 80%"
 > Code highlighting:
 >   {{{#!php
 >   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().

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/59774#comment:2>
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