wp_list_pluck( array $input_list, int|string $field, int|string $index_key = null ): array

Plucks a certain field out of each object or array in an array.

Contents

Description

This has the same functionality and prototype of array_column() (PHP 5.5) but also supports objects.

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Parameters

$input_list array Required
List of objects or arrays.
$field int|string Required
Field from the object to place instead of the entire object.
$index_key int|string Optional
Field from the object to use as keys for the new array.

Default: null

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Return

array Array of found values. If $index_key is set, an array of found values with keys corresponding to $index_key. If $index_key is null, array keys from the original $input_list will be preserved in the results.

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Source

File: wp-includes/functions.php. View all references 

function wp_list_pluck( $input_list, $field, $index_key = null ) {
	if ( ! is_array( $input_list ) ) {
		return array();
	}

	$util = new WP_List_Util( $input_list );

	return $util->pluck( $field, $index_key );
}

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Used By

Used By
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Updates parent post caches for a list of post objects.
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Searches the object type content for a given search request.
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Filters the given oEmbed HTML to make sure iframes have a title attribute.
WP_REST_Post_Search_Handler::search_items() wp-includes/rest-api/search/class-wp-rest-post-search-handler.php

Searches the object type content for a given search request.
WP_Widget_Media_Gallery::render_media() wp-includes/widgets/class-wp-widget-media-gallery.php

Render the media on the frontend.
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Render the media on the frontend.
WP_Widget_Media_Video::render_media() wp-includes/widgets/class-wp-widget-media-video.php

Render the media on the frontend.
WP_Widget_Media::form() wp-includes/widgets/class-wp-widget-media.php

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WP_Widget_Media::widget() wp-includes/widgets/class-wp-widget-media.php

Displays the widget on the front-end.
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Imports theme starter content into the customized state.
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Prepares a single post output for response.
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Prepares a post type object for serialization.
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Retrieves the query results.
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Fetch descendants for located comments.
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Gets dirty pre-sanitized setting values in the current customized state.
WP_Automatic_Updater::send_debug_email() wp-admin/includes/class-wp-automatic-updater.php

Prepares and sends an email of a full log of background update results, useful for debugging and geekery.
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Gets comma-separated list of terms available to edit for the given post ID.
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Adds hidden fields with the data for use in the inline editor for posts and pages.
WP_Media_List_Table::display_rows() wp-admin/includes/class-wp-media-list-table.php
WP_Comments_List_Table::prepare_items() wp-admin/includes/class-wp-comments-list-table.php
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Retrieves the terms of the taxonomy that are attached to the post.
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Retrieves an array of posts based on query variables.
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Transforms a single query, from one field to another.
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Adds a new term to the database.
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Removes a term from the database.
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Retrieves galleries from the passed post’s content.
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Updates a post with new post data.
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Changelog

Changelog
Version Description
4.7.0 Uses WP_List_Util class.
4.0.0 $index_key parameter added.
3.1.0 Introduced.

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User Contributed Notes

  1. Skip to note 1 content
    You must log in to vote on the helpfulness of this noteVote results for this note: 8You must log in to vote on the helpfulness of this note
    Contributed by Barbara Ford —

    This is an example of how to use this function.

    The following is an array listing foods:

    $foods = array(
	array(
		'name'  => 'Banana',
		'color' => 'Yellow',
	),
	array(
		'name'  => 'Apple',
		'color' => 'Red',
	),
	array(
		'name'  => 'Lettuce',
		'color' => 'Green',
	),
	array(
		'name'  => 'Apple',
		'color' => 'Red',
	),
);

    The names of each food can easily be “plucked” from the $foods array using wp_list_pluck().

    $food_names = wp_list_pluck( $foods, 'name' );

    $food_names will now contain a numerically indexed array of food names equivalent to:

    array(
	'Banana',
	'Apple',
	'Lettuce',
	'Apple'
);
  2. Skip to note 2 content
    You must log in to vote on the helpfulness of this noteVote results for this note: 7You must log in to vote on the helpfulness of this note
    Contributed by bcworkz —

    Use of the $index_key argument is best reserved for unique or index fields, otherwise data could be missing from the returned array. Consider this modified $foods list from the previous example:

    $foods = array(
    array(
        'name'  => 'Banana',
        'color' => 'Yellow',
    ),
    array(
        'name'  => 'Apple',
        'color' => 'Red',
    ),
    array(
        'name'  => 'Kiwi',
        'color' => null,
    ),
    array(
        'name'  => 'Lettuce',
        'color' => 'Green',
    ),
    array(
        'name'  => 'Cherry',
        'color' => 'Red',
    ),
);

    Using ‘color’ as $index_key is questionable.

    $food_names = wp_list_pluck( $foods, 'name', 'color' );

    $food_names contains an associative array equivalent to:

    array(
    'Yellow' => 'Banana',
    'Red'    => 'Cherry',
     0       => 'Kiwi',
    'Green'  => 'Lettuce',
)

    The ‘Apple’ value was overwritten by the subsequent ‘Cherry’ since they both had a ‘Red’ index key value. Since ‘Kiwi’ had an unusable color value, its key is simply indexed.

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