class WP_List_Table {}

Base class for displaying a list of items in an ajaxified HTML table.

More Information

Role of WP_List_Table

This class is used to generate the List Tables that populate WordPress’ various admin screens. It has an advantage over previous implementations in that it can be dynamically altered with AJAX and may be hooked in future WordPress releases.

Usage

This class is meant to be used as a kind of framework, since any data queries need to be loaded, sorted, and filtered manually. Nevertheless, it is potentially a very powerful tool for developers as it creates WordPress-standard list tables, which makes it very easy to implement advanced features like pagination, actions, bulk actions, and filtering.

To use the WP_List_Table, you first create a new class that extends the original. Your new class must be instantiated, and the prepare_items() and display() methods called explicitly on the instance. See the method descriptions below for more details.

In the WordPress Core

The WordPress core loads and returns its classes dynamically by using the _get_list_table() function, which automatically loads the appropriate extended class and instantiates it. This is a private function, however, and should not be used by developers.

Developer Usage

Since this class is marked as private, developers should use this only at their own risk as this class is subject to change in future WordPress releases. Any developers using this class are strongly encouraged to test their plugins with all WordPress beta/RC releases to maintain compatibility.

Since developers cannot use the _get_list_table() function directly, the class needs to be extended and instantiated manually, like so…

class Example_List_Table extends WP_List_Table {}
$example_lt = new Example_List_Table();

The above example won’t be able to output anything meaningful, however, as several methods MUST be specified (as well as your data) in order for WP_List_Table to render a useful table.

Methods and Properties

Please refer source code for the complete lists of methods and properties. Below description may cover some of them.

Properties

The following properties are built into the base WP_List_Table class. Note that the magic methods __get and __set of WP_List_Table will prevent setting other class instance variables in a subclass of WP_List_Table, please use the recommended variables:

$items
This is used to store the raw data you want to display. Generally you will set this property directly in the prepare_items() method.
$_args
Stores various information about the current table (as an array). This generally isn’t manipulated directly.
$_pagination_args
Stores information needed for handling table pagination (as an array). This generally isn’t manipulated directly, but rather used with get_pagination_arg( string ) or set_pagination_args(array).
$screen
This can be used to store the current screen, when it’s necessary to keep it consistent with the entire instance.
$_actions
Stores cached bulk actions. This generally isn’t manipulated directly.
$_pagination
Stores cached pagination output. This generally isn’t manipulated directly.

Extended Properties

These properties are not built-in, but are expected by several class methods. You must define them manually in your extended class.

$_column_headers
In core, this property is assigned automatically. Developers must manually define it in their prepare_items() or __construct() methods.
This property requires a 4-value array :

  • The first value is an array containing column slugs and titles (see the get_columns() method).
  • The second value is an array containing the values of fields to be hidden.
  • The third value is an array of columns that should allow sorting (see the get_sortable_columns() method).
  • The fourth value is a string defining which column is deemed to be the primary one, displaying the row’s actions (edit, view, etc). The value should match that of one of your column slugs in the first value.

Extended Methods

These methods are not included in the base class but can, and should, be defined in your extended class!

column_default( $item, $column_name )
This is method that is used to render a column when no other specific method exists for that column. When WP_List_Tables attempts to render your columns (within single_row_columns()), it first checks for a column-specific method. If none exists, it defaults to this method instead. This method accepts two arguments, a single $item array and the $column_name (as a slug).
NOTICE: As of WordPress 3.5.1, in core $item is passed an Object, not an array.
column_$custom( $item )
Custom columns must be provided by the developer and can be used to handle each type column individually. For example: if a method named column_movie_title() were provided, it would be used to render any column that had the slug “movie_title“. This function accepts one argument – a single $item array.
NOTICE: As of WordPress 3.5.1, in core $item is passed an Object, not an array.

Methods

NameDescription
WP_List_Table::__callMakes private/protected methods readable for backward compatibility.
WP_List_Table::__constructConstructor.
WP_List_Table::__getMakes private properties readable for backward compatibility.
WP_List_Table::__issetMakes private properties checkable for backward compatibility.
WP_List_Table::__setMakes private properties settable for backward compatibility.
WP_List_Table::__unsetMakes private properties un-settable for backward compatibility.
WP_List_Table::_js_varsSends required variables to JavaScript land.
WP_List_Table::ajax_responseHandles an incoming ajax request (called from admin-ajax.php)
WP_List_Table::ajax_user_canChecks the current user’s permissions
WP_List_Table::bulk_actionsDisplays the bulk actions dropdown.
WP_List_Table::column_cb
WP_List_Table::column_default
WP_List_Table::comments_bubbleDisplays a comment count bubble.
WP_List_Table::current_actionGets the current action selected from the bulk actions dropdown.
WP_List_Table::displayDisplays the table.
WP_List_Table::display_rowsGenerates the table rows.
WP_List_Table::display_rows_or_placeholderGenerates the tbody element for the list table.
WP_List_Table::display_tablenavGenerates the table navigation above or below the table
WP_List_Table::extra_tablenavDisplays extra controls between bulk actions and pagination.
WP_List_Table::get_bulk_actionsRetrieves the list of bulk actions available for this table.
WP_List_Table::get_column_countReturns the number of visible columns.
WP_List_Table::get_column_infoGets a list of all, hidden, and sortable columns, with filter applied.
WP_List_Table::get_columnsGets a list of columns.
WP_List_Table::get_default_primary_column_nameGets the name of the default primary column.
WP_List_Table::get_items_per_pageGets the number of items to display on a single page.
WP_List_Table::get_pagenumGets the current page number.
WP_List_Table::get_pagination_argAccess the pagination args.
WP_List_Table::get_primary_columnGets the name of the primary column.
WP_List_Table::get_primary_column_nameGets the name of the primary column.
WP_List_Table::get_sortable_columnsGets a list of sortable columns.
WP_List_Table::get_table_classesGets a list of CSS classes for the WP_List_Table table tag.
WP_List_Table::get_viewsGets the list of views available on this table.
WP_List_Table::get_views_linksGenerates views links.
WP_List_Table::handle_row_actionsGenerates and display row actions links for the list table.
WP_List_Table::has_itemsDetermines whether the table has items to display or not
WP_List_Table::months_dropdownDisplays a dropdown for filtering items in the list table by month.
WP_List_Table::no_itemsMessage to be displayed when there are no items
WP_List_Table::paginationDisplays the pagination.
WP_List_Table::prepare_itemsPrepares the list of items for displaying.
WP_List_Table::print_column_headersPrints column headers, accounting for hidden and sortable columns.
WP_List_Table::print_table_descriptionPrint a table description with information about current sorting and order.
WP_List_Table::row_actionsGenerates the required HTML for a list of row action links.
WP_List_Table::search_boxDisplays the search box.
WP_List_Table::set_pagination_argsSets all the necessary pagination arguments.
WP_List_Table::single_rowGenerates content for a single row of the table.
WP_List_Table::single_row_columnsGenerates the columns for a single row of the table.
WP_List_Table::view_switcherDisplays a view switcher.
WP_List_Table::viewsDisplays the list of views available on this table.

Source

class WP_List_Table {

	/**
	 * The current list of items.
	 *
	 * @since 3.1.0
	 * @var array
	 */
	public $items;

	/**
	 * Various information about the current table.
	 *
	 * @since 3.1.0
	 * @var array
	 */
	protected $_args;

	/**
	 * Various information needed for displaying the pagination.
	 *
	 * @since 3.1.0
	 * @var array
	 */
	protected $_pagination_args = array();

	/**
	 * The current screen.
	 *
	 * @since 3.1.0
	 * @var WP_Screen
	 */
	protected $screen;

	/**
	 * Cached bulk actions.
	 *
	 * @since 3.1.0
	 * @var array
	 */
	private $_actions;

	/**
	 * Cached pagination output.
	 *
	 * @since 3.1.0
	 * @var string
	 */
	private $_pagination;

	/**
	 * The view switcher modes.
	 *
	 * @since 4.1.0
	 * @var array
	 */
	protected $modes = array();

	/**
	 * Stores the value returned by ->get_column_info().
	 *
	 * @since 4.1.0
	 * @var array
	 */
	protected $_column_headers;

	/**
	 * {@internal Missing Summary}
	 *
	 * @var array
	 */
	protected $compat_fields = array( '_args', '_pagination_args', 'screen', '_actions', '_pagination' );

	/**
	 * {@internal Missing Summary}
	 *
	 * @var array
	 */
	protected $compat_methods = array(
		'set_pagination_args',
		'get_views',
		'get_bulk_actions',
		'bulk_actions',
		'row_actions',
		'months_dropdown',
		'view_switcher',
		'comments_bubble',
		'get_items_per_page',
		'pagination',
		'get_sortable_columns',
		'get_column_info',
		'get_table_classes',
		'display_tablenav',
		'extra_tablenav',
		'single_row_columns',
	);

	/**
	 * Constructor.
	 *
	 * The child class should call this constructor from its own constructor to override
	 * the default $args.
	 *
	 * @since 3.1.0
	 *
	 * @param array|string $args {
	 *     Array or string of arguments.
	 *
	 *     @type string $plural   Plural value used for labels and the objects being listed.
	 *                            This affects things such as CSS class-names and nonces used
	 *                            in the list table, e.g. 'posts'. Default empty.
	 *     @type string $singular Singular label for an object being listed, e.g. 'post'.
	 *                            Default empty
	 *     @type bool   $ajax     Whether the list table supports Ajax. This includes loading
	 *                            and sorting data, for example. If true, the class will call
	 *                            the _js_vars() method in the footer to provide variables
	 *                            to any scripts handling Ajax events. Default false.
	 *     @type string $screen   String containing the hook name used to determine the current
	 *                            screen. If left null, the current screen will be automatically set.
	 *                            Default null.
	 * }
	 */
	public function __construct( $args = array() ) {
		$args = wp_parse_args(
			$args,
			array(
				'plural'   => '',
				'singular' => '',
				'ajax'     => false,
				'screen'   => null,
			)
		);

		$this->screen = convert_to_screen( $args['screen'] );

		add_filter( "manage_{$this->screen->id}_columns", array( $this, 'get_columns' ), 0 );

		if ( ! $args['plural'] ) {
			$args['plural'] = $this->screen->base;
		}

		$args['plural']   = sanitize_key( $args['plural'] );
		$args['singular'] = sanitize_key( $args['singular'] );

		$this->_args = $args;

		if ( $args['ajax'] ) {
			// wp_enqueue_script( 'list-table' );
			add_action( 'admin_footer', array( $this, '_js_vars' ) );
		}

		if ( empty( $this->modes ) ) {
			$this->modes = array(
				'list'    => __( 'Compact view' ),
				'excerpt' => __( 'Extended view' ),
			);
		}
	}

	/**
	 * Makes private properties readable for backward compatibility.
	 *
	 * @since 4.0.0
	 * @since 6.4.0 Getting a dynamic property is deprecated.
	 *
	 * @param string $name Property to get.
	 * @return mixed Property.
	 */
	public function __get( $name ) {
		if ( in_array( $name, $this->compat_fields, true ) ) {
			return $this->$name;
		}

		wp_trigger_error(
			__METHOD__,
			"The property `{$name}` is not declared. Getting a dynamic property is " .
			'deprecated since version 6.4.0! Instead, declare the property on the class.',
			E_USER_DEPRECATED
		);
		return null;
	}

	/**
	 * Makes private properties settable for backward compatibility.
	 *
	 * @since 4.0.0
	 * @since 6.4.0 Setting a dynamic property is deprecated.
	 *
	 * @param string $name  Property to check if set.
	 * @param mixed  $value Property value.
	 */
	public function __set( $name, $value ) {
		if ( in_array( $name, $this->compat_fields, true ) ) {
			$this->$name = $value;
			return;
		}

		wp_trigger_error(
			__METHOD__,
			"The property `{$name}` is not declared. Setting a dynamic property is " .
			'deprecated since version 6.4.0! Instead, declare the property on the class.',
			E_USER_DEPRECATED
		);
	}

	/**
	 * Makes private properties checkable for backward compatibility.
	 *
	 * @since 4.0.0
	 * @since 6.4.0 Checking a dynamic property is deprecated.
	 *
	 * @param string $name Property to check if set.
	 * @return bool Whether the property is a back-compat property and it is set.
	 */
	public function __isset( $name ) {
		if ( in_array( $name, $this->compat_fields, true ) ) {
			return isset( $this->$name );
		}

		wp_trigger_error(
			__METHOD__,
			"The property `{$name}` is not declared. Checking `isset()` on a dynamic property " .
			'is deprecated since version 6.4.0! Instead, declare the property on the class.',
			E_USER_DEPRECATED
		);
		return false;
	}

	/**
	 * Makes private properties un-settable for backward compatibility.
	 *
	 * @since 4.0.0
	 * @since 6.4.0 Unsetting a dynamic property is deprecated.
	 *
	 * @param string $name Property to unset.
	 */
	public function __unset( $name ) {
		if ( in_array( $name, $this->compat_fields, true ) ) {
			unset( $this->$name );
			return;
		}

		wp_trigger_error(
			__METHOD__,
			"A property `{$name}` is not declared. Unsetting a dynamic property is " .
			'deprecated since version 6.4.0! Instead, declare the property on the class.',
			E_USER_DEPRECATED
		);
	}

	/**
	 * Makes private/protected methods readable for backward compatibility.
	 *
	 * @since 4.0.0
	 *
	 * @param string $name      Method to call.
	 * @param array  $arguments Arguments to pass when calling.
	 * @return mixed|bool Return value of the callback, false otherwise.
	 */
	public function __call( $name, $arguments ) {
		if ( in_array( $name, $this->compat_methods, true ) ) {
			return $this->$name( ...$arguments );
		}
		return false;
	}

	/**
	 * Checks the current user's permissions
	 *
	 * @since 3.1.0
	 * @abstract
	 */
	public function ajax_user_can() {
		die( 'function WP_List_Table::ajax_user_can() must be overridden in a subclass.' );
	}

	/**
	 * Prepares the list of items for displaying.
	 *
	 * @uses WP_List_Table::set_pagination_args()
	 *
	 * @since 3.1.0
	 * @abstract
	 */
	public function prepare_items() {
		die( 'function WP_List_Table::prepare_items() must be overridden in a subclass.' );
	}

	/**
	 * Sets all the necessary pagination arguments.
	 *
	 * @since 3.1.0
	 *
	 * @param array|string $args Array or string of arguments with information about the pagination.
	 */
	protected function set_pagination_args( $args ) {
		$args = wp_parse_args(
			$args,
			array(
				'total_items' => 0,
				'total_pages' => 0,
				'per_page'    => 0,
			)
		);

		if ( ! $args['total_pages'] && $args['per_page'] > 0 ) {
			$args['total_pages'] = (int) ceil( $args['total_items'] / $args['per_page'] );
		}

		// Redirect if page number is invalid and headers are not already sent.
		if ( ! headers_sent() && ! wp_doing_ajax() && $args['total_pages'] > 0 && $this->get_pagenum() > $args['total_pages'] ) {
			wp_redirect( add_query_arg( 'paged', $args['total_pages'] ) );
			exit;
		}

		$this->_pagination_args = $args;
	}

	/**
	 * Access the pagination args.
	 *
	 * @since 3.1.0
	 *
	 * @param string $key Pagination argument to retrieve. Common values include 'total_items',
	 *                    'total_pages', 'per_page', or 'infinite_scroll'.
	 * @return int Number of items that correspond to the given pagination argument.
	 */
	public function get_pagination_arg( $key ) {
		if ( 'page' === $key ) {
			return $this->get_pagenum();
		}

		if ( isset( $this->_pagination_args[ $key ] ) ) {
			return $this->_pagination_args[ $key ];
		}

		return 0;
	}

	/**
	 * Determines whether the table has items to display or not
	 *
	 * @since 3.1.0
	 *
	 * @return bool
	 */
	public function has_items() {
		return ! empty( $this->items );
	}

	/**
	 * Message to be displayed when there are no items
	 *
	 * @since 3.1.0
	 */
	public function no_items() {
		_e( 'No items found.' );
	}

	/**
	 * Displays the search box.
	 *
	 * @since 3.1.0
	 *
	 * @param string $text     The 'submit' button label.
	 * @param string $input_id ID attribute value for the search input field.
	 */
	public function search_box( $text, $input_id ) {
		if ( empty( $_REQUEST['s'] ) && ! $this->has_items() ) {
			return;
		}

		$input_id = $input_id . '-search-input';

		if ( ! empty( $_REQUEST['orderby'] ) ) {
			if ( is_array( $_REQUEST['orderby'] ) ) {
				foreach ( $_REQUEST['orderby'] as $key => $value ) {
					echo '<input type="hidden" name="orderby[' . esc_attr( $key ) . ']" value="' . esc_attr( $value ) . '" />';
				}
			} else {
				echo '<input type="hidden" name="orderby" value="' . esc_attr( $_REQUEST['orderby'] ) . '" />';
			}
		}
		if ( ! empty( $_REQUEST['order'] ) ) {
			echo '<input type="hidden" name="order" value="' . esc_attr( $_REQUEST['order'] ) . '" />';
		}
		if ( ! empty( $_REQUEST['post_mime_type'] ) ) {
			echo '<input type="hidden" name="post_mime_type" value="' . esc_attr( $_REQUEST['post_mime_type'] ) . '" />';
		}
		if ( ! empty( $_REQUEST['detached'] ) ) {
			echo '<input type="hidden" name="detached" value="' . esc_attr( $_REQUEST['detached'] ) . '" />';
		}
		?>
<p class="search-box">
	<label class="screen-reader-text" for="<?php echo esc_attr( $input_id ); ?>"><?php echo $text; ?>:</label>
	<input type="search" id="<?php echo esc_attr( $input_id ); ?>" name="s" value="<?php _admin_search_query(); ?>" />
		<?php submit_button( $text, '', '', false, array( 'id' => 'search-submit' ) ); ?>
</p>
		<?php
	}

	/**
	 * Generates views links.
	 *
	 * @since 6.1.0
	 *
	 * @param array $link_data {
	 *     An array of link data.
	 *
	 *     @type string $url     The link URL.
	 *     @type string $label   The link label.
	 *     @type bool   $current Optional. Whether this is the currently selected view.
	 * }
	 * @return string[] An array of link markup. Keys match the `$link_data` input array.
	 */
	protected function get_views_links( $link_data = array() ) {
		if ( ! is_array( $link_data ) ) {
			_doing_it_wrong(
				__METHOD__,
				sprintf(
					/* translators: %s: The $link_data argument. */
					__( 'The %s argument must be an array.' ),
					'<code>$link_data</code>'
				),
				'6.1.0'
			);

			return array( '' );
		}

		$views_links = array();

		foreach ( $link_data as $view => $link ) {
			if ( empty( $link['url'] ) || ! is_string( $link['url'] ) || '' === trim( $link['url'] ) ) {
				_doing_it_wrong(
					__METHOD__,
					sprintf(
						/* translators: %1$s: The argument name. %2$s: The view name. */
						__( 'The %1$s argument must be a non-empty string for %2$s.' ),
						'<code>url</code>',
						'<code>' . esc_html( $view ) . '</code>'
					),
					'6.1.0'
				);

				continue;
			}

			if ( empty( $link['label'] ) || ! is_string( $link['label'] ) || '' === trim( $link['label'] ) ) {
				_doing_it_wrong(
					__METHOD__,
					sprintf(
						/* translators: %1$s: The argument name. %2$s: The view name. */
						__( 'The %1$s argument must be a non-empty string for %2$s.' ),
						'<code>label</code>',
						'<code>' . esc_html( $view ) . '</code>'
					),
					'6.1.0'
				);

				continue;
			}

			$views_links[ $view ] = sprintf(
				'<a href="%s"%s>%s</a>',
				esc_url( $link['url'] ),
				isset( $link['current'] ) && true === $link['current'] ? ' class="current" aria-current="page"' : '',
				$link['label']
			);
		}

		return $views_links;
	}

	/**
	 * Gets the list of views available on this table.
	 *
	 * The format is an associative array:
	 * - `'id' => 'link'`
	 *
	 * @since 3.1.0
	 *
	 * @return array
	 */
	protected function get_views() {
		return array();
	}

	/**
	 * Displays the list of views available on this table.
	 *
	 * @since 3.1.0
	 */
	public function views() {
		$views = $this->get_views();
		/**
		 * Filters the list of available list table views.
		 *
		 * The dynamic portion of the hook name, `$this->screen->id`, refers
		 * to the ID of the current screen.
		 *
		 * @since 3.1.0
		 *
		 * @param string[] $views An array of available list table views.
		 */
		$views = apply_filters( "views_{$this->screen->id}", $views );

		if ( empty( $views ) ) {
			return;
		}

		$this->screen->render_screen_reader_content( 'heading_views' );

		echo "<ul class='subsubsub'>\n";
		foreach ( $views as $class => $view ) {
			$views[ $class ] = "\t<li class='$class'>$view";
		}
		echo implode( " |</li>\n", $views ) . "</li>\n";
		echo '</ul>';
	}

	/**
	 * Retrieves the list of bulk actions available for this table.
	 *
	 * The format is an associative array where each element represents either a top level option value and label, or
	 * an array representing an optgroup and its options.
	 *
	 * For a standard option, the array element key is the field value and the array element value is the field label.
	 *
	 * For an optgroup, the array element key is the label and the array element value is an associative array of
	 * options as above.
	 *
	 * Example:
	 *
	 *     [
	 *         'edit'         => 'Edit',
	 *         'delete'       => 'Delete',
	 *         'Change State' => [
	 *             'feature' => 'Featured',
	 *             'sale'    => 'On Sale',
	 *         ]
	 *     ]
	 *
	 * @since 3.1.0
	 * @since 5.6.0 A bulk action can now contain an array of options in order to create an optgroup.
	 *
	 * @return array
	 */
	protected function get_bulk_actions() {
		return array();
	}

	/**
	 * Displays the bulk actions dropdown.
	 *
	 * @since 3.1.0
	 *
	 * @param string $which The location of the bulk actions: Either 'top' or 'bottom'.
	 *                      This is designated as optional for backward compatibility.
	 */
	protected function bulk_actions( $which = '' ) {
		if ( is_null( $this->_actions ) ) {
			$this->_actions = $this->get_bulk_actions();

			/**
			 * Filters the items in the bulk actions menu of the list table.
			 *
			 * The dynamic portion of the hook name, `$this->screen->id`, refers
			 * to the ID of the current screen.
			 *
			 * @since 3.1.0
			 * @since 5.6.0 A bulk action can now contain an array of options in order to create an optgroup.
			 *
			 * @param array $actions An array of the available bulk actions.
			 */
			$this->_actions = apply_filters( "bulk_actions-{$this->screen->id}", $this->_actions ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

			$two = '';
		} else {
			$two = '2';
		}

		if ( empty( $this->_actions ) ) {
			return;
		}

		echo '<label for="bulk-action-selector-' . esc_attr( $which ) . '" class="screen-reader-text">' .
			/* translators: Hidden accessibility text. */
			__( 'Select bulk action' ) .
		'</label>';
		echo '<select name="action' . $two . '" id="bulk-action-selector-' . esc_attr( $which ) . "\">\n";
		echo '<option value="-1">' . __( 'Bulk actions' ) . "</option>\n";

		foreach ( $this->_actions as $key => $value ) {
			if ( is_array( $value ) ) {
				echo "\t" . '<optgroup label="' . esc_attr( $key ) . '">' . "\n";

				foreach ( $value as $name => $title ) {
					$class = ( 'edit' === $name ) ? ' class="hide-if-no-js"' : '';

					echo "\t\t" . '<option value="' . esc_attr( $name ) . '"' . $class . '>' . $title . "</option>\n";
				}
				echo "\t" . "</optgroup>\n";
			} else {
				$class = ( 'edit' === $key ) ? ' class="hide-if-no-js"' : '';

				echo "\t" . '<option value="' . esc_attr( $key ) . '"' . $class . '>' . $value . "</option>\n";
			}
		}

		echo "</select>\n";

		submit_button( __( 'Apply' ), 'action', '', false, array( 'id' => "doaction$two" ) );
		echo "\n";
	}

	/**
	 * Gets the current action selected from the bulk actions dropdown.
	 *
	 * @since 3.1.0
	 *
	 * @return string|false The action name. False if no action was selected.
	 */
	public function current_action() {
		if ( isset( $_REQUEST['filter_action'] ) && ! empty( $_REQUEST['filter_action'] ) ) {
			return false;
		}

		if ( isset( $_REQUEST['action'] ) && '-1' !== $_REQUEST['action'] ) {
			return $_REQUEST['action'];
		}

		return false;
	}

	/**
	 * Generates the required HTML for a list of row action links.
	 *
	 * @since 3.1.0
	 *
	 * @param string[] $actions        An array of action links.
	 * @param bool     $always_visible Whether the actions should be always visible.
	 * @return string The HTML for the row actions.
	 */
	protected function row_actions( $actions, $always_visible = false ) {
		$action_count = count( $actions );

		if ( ! $action_count ) {
			return '';
		}

		$mode = get_user_setting( 'posts_list_mode', 'list' );

		if ( 'excerpt' === $mode ) {
			$always_visible = true;
		}

		$output = '<div class="' . ( $always_visible ? 'row-actions visible' : 'row-actions' ) . '">';

		$i = 0;

		foreach ( $actions as $action => $link ) {
			++$i;

			$separator = ( $i < $action_count ) ? ' | ' : '';

			$output .= "<span class='$action'>{$link}{$separator}</span>";
		}

		$output .= '</div>';

		$output .= '<button type="button" class="toggle-row"><span class="screen-reader-text">' .
			/* translators: Hidden accessibility text. */
			__( 'Show more details' ) .
		'</span></button>';

		return $output;
	}

	/**
	 * Displays a dropdown for filtering items in the list table by month.
	 *
	 * @since 3.1.0
	 *
	 * @global wpdb      $wpdb      WordPress database abstraction object.
	 * @global WP_Locale $wp_locale WordPress date and time locale object.
	 *
	 * @param string $post_type The post type.
	 */
	protected function months_dropdown( $post_type ) {
		global $wpdb, $wp_locale;

		/**
		 * Filters whether to remove the 'Months' drop-down from the post list table.
		 *
		 * @since 4.2.0
		 *
		 * @param bool   $disable   Whether to disable the drop-down. Default false.
		 * @param string $post_type The post type.
		 */
		if ( apply_filters( 'disable_months_dropdown', false, $post_type ) ) {
			return;
		}

		/**
		 * Filters whether to short-circuit performing the months dropdown query.
		 *
		 * @since 5.7.0
		 *
		 * @param object[]|false $months   'Months' drop-down results. Default false.
		 * @param string         $post_type The post type.
		 */
		$months = apply_filters( 'pre_months_dropdown_query', false, $post_type );

		if ( ! is_array( $months ) ) {
			$extra_checks = "AND post_status != 'auto-draft'";
			if ( ! isset( $_GET['post_status'] ) || 'trash' !== $_GET['post_status'] ) {
				$extra_checks .= " AND post_status != 'trash'";
			} elseif ( isset( $_GET['post_status'] ) ) {
				$extra_checks = $wpdb->prepare( ' AND post_status = %s', $_GET['post_status'] );
			}

			$months = $wpdb->get_results(
				$wpdb->prepare(
					"SELECT DISTINCT YEAR( post_date ) AS year, MONTH( post_date ) AS month
					FROM $wpdb->posts
					WHERE post_type = %s
					$extra_checks
					ORDER BY post_date DESC",
					$post_type
				)
			);
		}

		/**
		 * Filters the 'Months' drop-down results.
		 *
		 * @since 3.7.0
		 *
		 * @param object[] $months    Array of the months drop-down query results.
		 * @param string   $post_type The post type.
		 */
		$months = apply_filters( 'months_dropdown_results', $months, $post_type );

		$month_count = count( $months );

		if ( ! $month_count || ( 1 === $month_count && 0 === (int) $months[0]->month ) ) {
			return;
		}

		$m = isset( $_GET['m'] ) ? (int) $_GET['m'] : 0;
		?>
		<label for="filter-by-date" class="screen-reader-text"><?php echo get_post_type_object( $post_type )->labels->filter_by_date; ?></label>
		<select name="m" id="filter-by-date">
			<option<?php selected( $m, 0 ); ?> value="0"><?php _e( 'All dates' ); ?></option>
		<?php
		foreach ( $months as $arc_row ) {
			if ( 0 === (int) $arc_row->year ) {
				continue;
			}

			$month = zeroise( $arc_row->month, 2 );
			$year  = $arc_row->year;

			printf(
				"<option %s value='%s'>%s</option>\n",
				selected( $m, $year . $month, false ),
				esc_attr( $arc_row->year . $month ),
				/* translators: 1: Month name, 2: 4-digit year. */
				sprintf( __( '%1$s %2$d' ), $wp_locale->get_month( $month ), $year )
			);
		}
		?>
		</select>
		<?php
	}

	/**
	 * Displays a view switcher.
	 *
	 * @since 3.1.0
	 *
	 * @param string $current_mode
	 */
	protected function view_switcher( $current_mode ) {
		?>
		<input type="hidden" name="mode" value="<?php echo esc_attr( $current_mode ); ?>" />
		<div class="view-switch">
		<?php
		foreach ( $this->modes as $mode => $title ) {
			$classes      = array( 'view-' . $mode );
			$aria_current = '';

			if ( $current_mode === $mode ) {
				$classes[]    = 'current';
				$aria_current = ' aria-current="page"';
			}

			printf(
				"<a href='%s' class='%s' id='view-switch-$mode'$aria_current>" .
					"<span class='screen-reader-text'>%s</span>" .
				"</a>\n",
				esc_url( remove_query_arg( 'attachment-filter', add_query_arg( 'mode', $mode ) ) ),
				implode( ' ', $classes ),
				$title
			);
		}
		?>
		</div>
		<?php
	}

	/**
	 * Displays a comment count bubble.
	 *
	 * @since 3.1.0
	 *
	 * @param int $post_id          The post ID.
	 * @param int $pending_comments Number of pending comments.
	 */
	protected function comments_bubble( $post_id, $pending_comments ) {
		$post_object   = get_post( $post_id );
		$edit_post_cap = $post_object ? 'edit_post' : 'edit_posts';

		if ( ! current_user_can( $edit_post_cap, $post_id )
			&& ( post_password_required( $post_id )
				|| ! current_user_can( 'read_post', $post_id ) )
		) {
			// The user has no access to the post and thus cannot see the comments.
			return false;
		}

		$approved_comments = get_comments_number();

		$approved_comments_number = number_format_i18n( $approved_comments );
		$pending_comments_number  = number_format_i18n( $pending_comments );

		$approved_only_phrase = sprintf(
			/* translators: %s: Number of comments. */
			_n( '%s comment', '%s comments', $approved_comments ),
			$approved_comments_number
		);

		$approved_phrase = sprintf(
			/* translators: %s: Number of comments. */
			_n( '%s approved comment', '%s approved comments', $approved_comments ),
			$approved_comments_number
		);

		$pending_phrase = sprintf(
			/* translators: %s: Number of comments. */
			_n( '%s pending comment', '%s pending comments', $pending_comments ),
			$pending_comments_number
		);

		if ( ! $approved_comments && ! $pending_comments ) {
			// No comments at all.
			printf(
				'<span aria-hidden="true">&#8212;</span>' .
				'<span class="screen-reader-text">%s</span>',
				__( 'No comments' )
			);
		} elseif ( $approved_comments && 'trash' === get_post_status( $post_id ) ) {
			// Don't link the comment bubble for a trashed post.
			printf(
				'<span class="post-com-count post-com-count-approved">' .
					'<span class="comment-count-approved" aria-hidden="true">%s</span>' .
					'<span class="screen-reader-text">%s</span>' .
				'</span>',
				$approved_comments_number,
				$pending_comments ? $approved_phrase : $approved_only_phrase
			);
		} elseif ( $approved_comments ) {
			// Link the comment bubble to approved comments.
			printf(
				'<a href="%s" class="post-com-count post-com-count-approved">' .
					'<span class="comment-count-approved" aria-hidden="true">%s</span>' .
					'<span class="screen-reader-text">%s</span>' .
				'</a>',
				esc_url(
					add_query_arg(
						array(
							'p'              => $post_id,
							'comment_status' => 'approved',
						),
						admin_url( 'edit-comments.php' )
					)
				),
				$approved_comments_number,
				$pending_comments ? $approved_phrase : $approved_only_phrase
			);
		} else {
			// Don't link the comment bubble when there are no approved comments.
			printf(
				'<span class="post-com-count post-com-count-no-comments">' .
					'<span class="comment-count comment-count-no-comments" aria-hidden="true">%s</span>' .
					'<span class="screen-reader-text">%s</span>' .
				'</span>',
				$approved_comments_number,
				$pending_comments ?
				/* translators: Hidden accessibility text. */
				__( 'No approved comments' ) :
				/* translators: Hidden accessibility text. */
				__( 'No comments' )
			);
		}

		if ( $pending_comments ) {
			printf(
				'<a href="%s" class="post-com-count post-com-count-pending">' .
					'<span class="comment-count-pending" aria-hidden="true">%s</span>' .
					'<span class="screen-reader-text">%s</span>' .
				'</a>',
				esc_url(
					add_query_arg(
						array(
							'p'              => $post_id,
							'comment_status' => 'moderated',
						),
						admin_url( 'edit-comments.php' )
					)
				),
				$pending_comments_number,
				$pending_phrase
			);
		} else {
			printf(
				'<span class="post-com-count post-com-count-pending post-com-count-no-pending">' .
					'<span class="comment-count comment-count-no-pending" aria-hidden="true">%s</span>' .
					'<span class="screen-reader-text">%s</span>' .
				'</span>',
				$pending_comments_number,
				$approved_comments ?
				/* translators: Hidden accessibility text. */
				__( 'No pending comments' ) :
				/* translators: Hidden accessibility text. */
				__( 'No comments' )
			);
		}
	}

	/**
	 * Gets the current page number.
	 *
	 * @since 3.1.0
	 *
	 * @return int
	 */
	public function get_pagenum() {
		$pagenum = isset( $_REQUEST['paged'] ) ? absint( $_REQUEST['paged'] ) : 0;

		if ( isset( $this->_pagination_args['total_pages'] ) && $pagenum > $this->_pagination_args['total_pages'] ) {
			$pagenum = $this->_pagination_args['total_pages'];
		}

		return max( 1, $pagenum );
	}

	/**
	 * Gets the number of items to display on a single page.
	 *
	 * @since 3.1.0
	 *
	 * @param string $option        User option name.
	 * @param int    $default_value Optional. The number of items to display. Default 20.
	 * @return int
	 */
	protected function get_items_per_page( $option, $default_value = 20 ) {
		$per_page = (int) get_user_option( $option );
		if ( empty( $per_page ) || $per_page < 1 ) {
			$per_page = $default_value;
		}

		/**
		 * Filters the number of items to be displayed on each page of the list table.
		 *
		 * The dynamic hook name, `$option`, refers to the `per_page` option depending
		 * on the type of list table in use. Possible filter names include:
		 *
		 *  - `edit_comments_per_page`
		 *  - `sites_network_per_page`
		 *  - `site_themes_network_per_page`
		 *  - `themes_network_per_page`
		 *  - `users_network_per_page`
		 *  - `edit_post_per_page`
		 *  - `edit_page_per_page`
		 *  - `edit_{$post_type}_per_page`
		 *  - `edit_post_tag_per_page`
		 *  - `edit_category_per_page`
		 *  - `edit_{$taxonomy}_per_page`
		 *  - `site_users_network_per_page`
		 *  - `users_per_page`
		 *
		 * @since 2.9.0
		 *
		 * @param int $per_page Number of items to be displayed. Default 20.
		 */
		return (int) apply_filters( "{$option}", $per_page );
	}

	/**
	 * Displays the pagination.
	 *
	 * @since 3.1.0
	 *
	 * @param string $which The location of the pagination: Either 'top' or 'bottom'.
	 */
	protected function pagination( $which ) {
		if ( empty( $this->_pagination_args ) ) {
			return;
		}

		$total_items     = $this->_pagination_args['total_items'];
		$total_pages     = $this->_pagination_args['total_pages'];
		$infinite_scroll = false;
		if ( isset( $this->_pagination_args['infinite_scroll'] ) ) {
			$infinite_scroll = $this->_pagination_args['infinite_scroll'];
		}

		if ( 'top' === $which && $total_pages > 1 ) {
			$this->screen->render_screen_reader_content( 'heading_pagination' );
		}

		$output = '<span class="displaying-num">' . sprintf(
			/* translators: %s: Number of items. */
			_n( '%s item', '%s items', $total_items ),
			number_format_i18n( $total_items )
		) . '</span>';

		$current              = $this->get_pagenum();
		$removable_query_args = wp_removable_query_args();

		$current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );

		$current_url = remove_query_arg( $removable_query_args, $current_url );

		$page_links = array();

		$total_pages_before = '<span class="paging-input">';
		$total_pages_after  = '</span></span>';

		$disable_first = false;
		$disable_last  = false;
		$disable_prev  = false;
		$disable_next  = false;

		if ( 1 === $current ) {
			$disable_first = true;
			$disable_prev  = true;
		}
		if ( $total_pages === $current ) {
			$disable_last = true;
			$disable_next = true;
		}

		if ( $disable_first ) {
			$page_links[] = '<span class="tablenav-pages-navspan button disabled" aria-hidden="true">&laquo;</span>';
		} else {
			$page_links[] = sprintf(
				"<a class='first-page button' href='%s'>" .
					"<span class='screen-reader-text'>%s</span>" .
					"<span aria-hidden='true'>%s</span>" .
				'</a>',
				esc_url( remove_query_arg( 'paged', $current_url ) ),
				/* translators: Hidden accessibility text. */
				__( 'First page' ),
				'&laquo;'
			);
		}

		if ( $disable_prev ) {
			$page_links[] = '<span class="tablenav-pages-navspan button disabled" aria-hidden="true">&lsaquo;</span>';
		} else {
			$page_links[] = sprintf(
				"<a class='prev-page button' href='%s'>" .
					"<span class='screen-reader-text'>%s</span>" .
					"<span aria-hidden='true'>%s</span>" .
				'</a>',
				esc_url( add_query_arg( 'paged', max( 1, $current - 1 ), $current_url ) ),
				/* translators: Hidden accessibility text. */
				__( 'Previous page' ),
				'&lsaquo;'
			);
		}

		if ( 'bottom' === $which ) {
			$html_current_page  = $current;
			$total_pages_before = sprintf(
				'<span class="screen-reader-text">%s</span>' .
				'<span id="table-paging" class="paging-input">' .
				'<span class="tablenav-paging-text">',
				/* translators: Hidden accessibility text. */
				__( 'Current Page' )
			);
		} else {
			$html_current_page = sprintf(
				'<label for="current-page-selector" class="screen-reader-text">%s</label>' .
				"<input class='current-page' id='current-page-selector' type='text'
					name='paged' value='%s' size='%d' aria-describedby='table-paging' />" .
				"<span class='tablenav-paging-text'>",
				/* translators: Hidden accessibility text. */
				__( 'Current Page' ),
				$current,
				strlen( $total_pages )
			);
		}

		$html_total_pages = sprintf( "<span class='total-pages'>%s</span>", number_format_i18n( $total_pages ) );

		$page_links[] = $total_pages_before . sprintf(
			/* translators: 1: Current page, 2: Total pages. */
			_x( '%1$s of %2$s', 'paging' ),
			$html_current_page,
			$html_total_pages
		) . $total_pages_after;

		if ( $disable_next ) {
			$page_links[] = '<span class="tablenav-pages-navspan button disabled" aria-hidden="true">&rsaquo;</span>';
		} else {
			$page_links[] = sprintf(
				"<a class='next-page button' href='%s'>" .
					"<span class='screen-reader-text'>%s</span>" .
					"<span aria-hidden='true'>%s</span>" .
				'</a>',
				esc_url( add_query_arg( 'paged', min( $total_pages, $current + 1 ), $current_url ) ),
				/* translators: Hidden accessibility text. */
				__( 'Next page' ),
				'&rsaquo;'
			);
		}

		if ( $disable_last ) {
			$page_links[] = '<span class="tablenav-pages-navspan button disabled" aria-hidden="true">&raquo;</span>';
		} else {
			$page_links[] = sprintf(
				"<a class='last-page button' href='%s'>" .
					"<span class='screen-reader-text'>%s</span>" .
					"<span aria-hidden='true'>%s</span>" .
				'</a>',
				esc_url( add_query_arg( 'paged', $total_pages, $current_url ) ),
				/* translators: Hidden accessibility text. */
				__( 'Last page' ),
				'&raquo;'
			);
		}

		$pagination_links_class = 'pagination-links';
		if ( ! empty( $infinite_scroll ) ) {
			$pagination_links_class .= ' hide-if-js';
		}
		$output .= "\n<span class='$pagination_links_class'>" . implode( "\n", $page_links ) . '</span>';

		if ( $total_pages ) {
			$page_class = $total_pages < 2 ? ' one-page' : '';
		} else {
			$page_class = ' no-pages';
		}
		$this->_pagination = "<div class='tablenav-pages{$page_class}'>$output</div>";

		echo $this->_pagination;
	}

	/**
	 * Gets a list of columns.
	 *
	 * The format is:
	 * - `'internal-name' => 'Title'`
	 *
	 * @since 3.1.0
	 * @abstract
	 *
	 * @return array
	 */
	public function get_columns() {
		die( 'function WP_List_Table::get_columns() must be overridden in a subclass.' );
	}

	/**
	 * Gets a list of sortable columns.
	 *
	 * The format is:
	 * - `'internal-name' => 'orderby'`
	 * - `'internal-name' => array( 'orderby', bool, 'abbr', 'orderby-text', 'initially-sorted-column-order' )` -
	 * - `'internal-name' => array( 'orderby', 'asc' )` - The second element sets the initial sorting order.
	 * - `'internal-name' => array( 'orderby', true )`  - The second element makes the initial order descending.
	 *
	 * In the second format, passing true as second parameter will make the initial
	 * sorting order be descending. Following parameters add a short column name to
	 * be used as 'abbr' attribute, a translatable string for the current sorting,
	 * and the initial order for the initial sorted column, 'asc' or 'desc' (default: false).
	 *
	 * @since 3.1.0
	 * @since 6.3.0 Added 'abbr', 'orderby-text' and 'initially-sorted-column-order'.
	 *
	 * @return array
	 */
	protected function get_sortable_columns() {
		return array();
	}

	/**
	 * Gets the name of the default primary column.
	 *
	 * @since 4.3.0
	 *
	 * @return string Name of the default primary column, in this case, an empty string.
	 */
	protected function get_default_primary_column_name() {
		$columns = $this->get_columns();
		$column  = '';

		if ( empty( $columns ) ) {
			return $column;
		}

		/*
		 * We need a primary defined so responsive views show something,
		 * so let's fall back to the first non-checkbox column.
		 */
		foreach ( $columns as $col => $column_name ) {
			if ( 'cb' === $col ) {
				continue;
			}

			$column = $col;
			break;
		}

		return $column;
	}

	/**
	 * Gets the name of the primary column.
	 *
	 * Public wrapper for WP_List_Table::get_default_primary_column_name().
	 *
	 * @since 4.4.0
	 *
	 * @return string Name of the default primary column.
	 */
	public function get_primary_column() {
		return $this->get_primary_column_name();
	}

	/**
	 * Gets the name of the primary column.
	 *
	 * @since 4.3.0
	 *
	 * @return string The name of the primary column.
	 */
	protected function get_primary_column_name() {
		$columns = get_column_headers( $this->screen );
		$default = $this->get_default_primary_column_name();

		/*
		 * If the primary column doesn't exist,
		 * fall back to the first non-checkbox column.
		 */
		if ( ! isset( $columns[ $default ] ) ) {
			$default = self::get_default_primary_column_name();
		}

		/**
		 * Filters the name of the primary column for the current list table.
		 *
		 * @since 4.3.0
		 *
		 * @param string $default Column name default for the specific list table, e.g. 'name'.
		 * @param string $context Screen ID for specific list table, e.g. 'plugins'.
		 */
		$column = apply_filters( 'list_table_primary_column', $default, $this->screen->id );

		if ( empty( $column ) || ! isset( $columns[ $column ] ) ) {
			$column = $default;
		}

		return $column;
	}

	/**
	 * Gets a list of all, hidden, and sortable columns, with filter applied.
	 *
	 * @since 3.1.0
	 *
	 * @return array
	 */
	protected function get_column_info() {
		// $_column_headers is already set / cached.
		if (
			isset( $this->_column_headers ) &&
			is_array( $this->_column_headers )
		) {
			/*
			 * Backward compatibility for `$_column_headers` format prior to WordPress 4.3.
			 *
			 * In WordPress 4.3 the primary column name was added as a fourth item in the
			 * column headers property. This ensures the primary column name is included
			 * in plugins setting the property directly in the three item format.
			 */
			if ( 4 === count( $this->_column_headers ) ) {
				return $this->_column_headers;
			}

			$column_headers = array( array(), array(), array(), $this->get_primary_column_name() );
			foreach ( $this->_column_headers as $key => $value ) {
				$column_headers[ $key ] = $value;
			}

			$this->_column_headers = $column_headers;

			return $this->_column_headers;
		}

		$columns = get_column_headers( $this->screen );
		$hidden  = get_hidden_columns( $this->screen );

		$sortable_columns = $this->get_sortable_columns();
		/**
		 * Filters the list table sortable columns for a specific screen.
		 *
		 * The dynamic portion of the hook name, `$this->screen->id`, refers
		 * to the ID of the current screen.
		 *
		 * @since 3.1.0
		 *
		 * @param array $sortable_columns An array of sortable columns.
		 */
		$_sortable = apply_filters( "manage_{$this->screen->id}_sortable_columns", $sortable_columns );

		$sortable = array();
		foreach ( $_sortable as $id => $data ) {
			if ( empty( $data ) ) {
				continue;
			}

			$data = (array) $data;
			// Descending initial sorting.
			if ( ! isset( $data[1] ) ) {
				$data[1] = false;
			}
			// Current sorting translatable string.
			if ( ! isset( $data[2] ) ) {
				$data[2] = '';
			}
			// Initial view sorted column and asc/desc order, default: false.
			if ( ! isset( $data[3] ) ) {
				$data[3] = false;
			}
			// Initial order for the initial sorted column, default: false.
			if ( ! isset( $data[4] ) ) {
				$data[4] = false;
			}

			$sortable[ $id ] = $data;
		}

		$primary               = $this->get_primary_column_name();
		$this->_column_headers = array( $columns, $hidden, $sortable, $primary );

		return $this->_column_headers;
	}

	/**
	 * Returns the number of visible columns.
	 *
	 * @since 3.1.0
	 *
	 * @return int
	 */
	public function get_column_count() {
		list ( $columns, $hidden ) = $this->get_column_info();
		$hidden                    = array_intersect( array_keys( $columns ), array_filter( $hidden ) );
		return count( $columns ) - count( $hidden );
	}

	/**
	 * Prints column headers, accounting for hidden and sortable columns.
	 *
	 * @since 3.1.0
	 *
	 * @param bool $with_id Whether to set the ID attribute or not
	 */
	public function print_column_headers( $with_id = true ) {
		list( $columns, $hidden, $sortable, $primary ) = $this->get_column_info();

		$current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );
		$current_url = remove_query_arg( 'paged', $current_url );

		// When users click on a column header to sort by other columns.
		if ( isset( $_GET['orderby'] ) ) {
			$current_orderby = $_GET['orderby'];
			// In the initial view there's no orderby parameter.
		} else {
			$current_orderby = '';
		}

		// Not in the initial view and descending order.
		if ( isset( $_GET['order'] ) && 'desc' === $_GET['order'] ) {
			$current_order = 'desc';
		} else {
			// The initial view is not always 'asc', we'll take care of this below.
			$current_order = 'asc';
		}

		if ( ! empty( $columns['cb'] ) ) {
			static $cb_counter = 1;
			$columns['cb']     = '<input id="cb-select-all-' . $cb_counter . '" type="checkbox" />
			<label for="cb-select-all-' . $cb_counter . '">' .
				'<span class="screen-reader-text">' .
					/* translators: Hidden accessibility text. */
					__( 'Select All' ) .
				'</span>' .
				'</label>';
			++$cb_counter;
		}

		foreach ( $columns as $column_key => $column_display_name ) {
			$class          = array( 'manage-column', "column-$column_key" );
			$aria_sort_attr = '';
			$abbr_attr      = '';
			$order_text     = '';

			if ( in_array( $column_key, $hidden, true ) ) {
				$class[] = 'hidden';
			}

			if ( 'cb' === $column_key ) {
				$class[] = 'check-column';
			} elseif ( in_array( $column_key, array( 'posts', 'comments', 'links' ), true ) ) {
				$class[] = 'num';
			}

			if ( $column_key === $primary ) {
				$class[] = 'column-primary';
			}

			if ( isset( $sortable[ $column_key ] ) ) {
				$orderby       = isset( $sortable[ $column_key ][0] ) ? $sortable[ $column_key ][0] : '';
				$desc_first    = isset( $sortable[ $column_key ][1] ) ? $sortable[ $column_key ][1] : false;
				$abbr          = isset( $sortable[ $column_key ][2] ) ? $sortable[ $column_key ][2] : '';
				$orderby_text  = isset( $sortable[ $column_key ][3] ) ? $sortable[ $column_key ][3] : '';
				$initial_order = isset( $sortable[ $column_key ][4] ) ? $sortable[ $column_key ][4] : '';

				/*
				 * We're in the initial view and there's no $_GET['orderby'] then check if the
				 * initial sorting information is set in the sortable columns and use that.
				 */
				if ( '' === $current_orderby && $initial_order ) {
					// Use the initially sorted column $orderby as current orderby.
					$current_orderby = $orderby;
					// Use the initially sorted column asc/desc order as initial order.
					$current_order = $initial_order;
				}

				/*
				 * True in the initial view when an initial orderby is set via get_sortable_columns()
				 * and true in the sorted views when the actual $_GET['orderby'] is equal to $orderby.
				 */
				if ( $current_orderby === $orderby ) {
					// The sorted column. The `aria-sort` attribute must be set only on the sorted column.
					if ( 'asc' === $current_order ) {
						$order          = 'desc';
						$aria_sort_attr = ' aria-sort="ascending"';
					} else {
						$order          = 'asc';
						$aria_sort_attr = ' aria-sort="descending"';
					}

					$class[] = 'sorted';
					$class[] = $current_order;
				} else {
					// The other sortable columns.
					$order = strtolower( $desc_first );

					if ( ! in_array( $order, array( 'desc', 'asc' ), true ) ) {
						$order = $desc_first ? 'desc' : 'asc';
					}

					$class[] = 'sortable';
					$class[] = 'desc' === $order ? 'asc' : 'desc';

					/* translators: Hidden accessibility text. */
					$asc_text = __( 'Sort ascending.' );
					/* translators: Hidden accessibility text. */
					$desc_text  = __( 'Sort descending.' );
					$order_text = 'asc' === $order ? $asc_text : $desc_text;
				}

				if ( '' !== $order_text ) {
					$order_text = ' <span class="screen-reader-text">' . $order_text . '</span>';
				}

				// Print an 'abbr' attribute if a value is provided via get_sortable_columns().
				$abbr_attr = $abbr ? ' abbr="' . esc_attr( $abbr ) . '"' : '';

				$column_display_name = sprintf(
					'<a href="%1$s">' .
						'<span>%2$s</span>' .
						'<span class="sorting-indicators">' .
							'<span class="sorting-indicator asc" aria-hidden="true"></span>' .
							'<span class="sorting-indicator desc" aria-hidden="true"></span>' .
						'</span>' .
						'%3$s' .
					'</a>',
					esc_url( add_query_arg( compact( 'orderby', 'order' ), $current_url ) ),
					$column_display_name,
					$order_text
				);
			}

			$tag   = ( 'cb' === $column_key ) ? 'td' : 'th';
			$scope = ( 'th' === $tag ) ? 'scope="col"' : '';
			$id    = $with_id ? "id='$column_key'" : '';

			if ( ! empty( $class ) ) {
				$class = "class='" . implode( ' ', $class ) . "'";
			}

			echo "<$tag $scope $id $class $aria_sort_attr $abbr_attr>$column_display_name</$tag>";
		}
	}

	/**
	 * Print a table description with information about current sorting and order.
	 *
	 * For the table initial view, information about initial orderby and order
	 * should be provided via get_sortable_columns().
	 *
	 * @since 6.3.0
	 * @access public
	 */
	public function print_table_description() {
		list( $columns, $hidden, $sortable ) = $this->get_column_info();

		if ( empty( $sortable ) ) {
			return;
		}

		// When users click on a column header to sort by other columns.
		if ( isset( $_GET['orderby'] ) ) {
			$current_orderby = $_GET['orderby'];
			// In the initial view there's no orderby parameter.
		} else {
			$current_orderby = '';
		}

		// Not in the initial view and descending order.
		if ( isset( $_GET['order'] ) && 'desc' === $_GET['order'] ) {
			$current_order = 'desc';
		} else {
			// The initial view is not always 'asc', we'll take care of this below.
			$current_order = 'asc';
		}

		foreach ( array_keys( $columns ) as $column_key ) {

			if ( isset( $sortable[ $column_key ] ) ) {
				$orderby       = isset( $sortable[ $column_key ][0] ) ? $sortable[ $column_key ][0] : '';
				$desc_first    = isset( $sortable[ $column_key ][1] ) ? $sortable[ $column_key ][1] : false;
				$abbr          = isset( $sortable[ $column_key ][2] ) ? $sortable[ $column_key ][2] : '';
				$orderby_text  = isset( $sortable[ $column_key ][3] ) ? $sortable[ $column_key ][3] : '';
				$initial_order = isset( $sortable[ $column_key ][4] ) ? $sortable[ $column_key ][4] : '';

				if ( ! is_string( $orderby_text ) || '' === $orderby_text ) {
					return;
				}
				/*
				 * We're in the initial view and there's no $_GET['orderby'] then check if the
				 * initial sorting information is set in the sortable columns and use that.
				 */
				if ( '' === $current_orderby && $initial_order ) {
					// Use the initially sorted column $orderby as current orderby.
					$current_orderby = $orderby;
					// Use the initially sorted column asc/desc order as initial order.
					$current_order = $initial_order;
				}

				/*
				 * True in the initial view when an initial orderby is set via get_sortable_columns()
				 * and true in the sorted views when the actual $_GET['orderby'] is equal to $orderby.
				 */
				if ( $current_orderby === $orderby ) {
					/* translators: Hidden accessibility text. */
					$asc_text = __( 'Ascending.' );
					/* translators: Hidden accessibility text. */
					$desc_text  = __( 'Descending.' );
					$order_text = 'asc' === $current_order ? $asc_text : $desc_text;
					echo '<caption class="screen-reader-text">' . $orderby_text . ' ' . $order_text . '</caption>';

					return;
				}
			}
		}
	}

	/**
	 * Displays the table.
	 *
	 * @since 3.1.0
	 */
	public function display() {
		$singular = $this->_args['singular'];

		$this->display_tablenav( 'top' );

		$this->screen->render_screen_reader_content( 'heading_list' );
		?>
<table class="wp-list-table <?php echo implode( ' ', $this->get_table_classes() ); ?>">
		<?php $this->print_table_description(); ?>
	<thead>
	<tr>
		<?php $this->print_column_headers(); ?>
	</tr>
	</thead>

	<tbody id="the-list"
		<?php
		if ( $singular ) {
			echo " data-wp-lists='list:$singular'";
		}
		?>
		>
		<?php $this->display_rows_or_placeholder(); ?>
	</tbody>

	<tfoot>
	<tr>
		<?php $this->print_column_headers( false ); ?>
	</tr>
	</tfoot>

</table>
		<?php
		$this->display_tablenav( 'bottom' );
	}

	/**
	 * Gets a list of CSS classes for the WP_List_Table table tag.
	 *
	 * @since 3.1.0
	 *
	 * @return string[] Array of CSS classes for the table tag.
	 */
	protected function get_table_classes() {
		$mode = get_user_setting( 'posts_list_mode', 'list' );

		$mode_class = esc_attr( 'table-view-' . $mode );

		return array( 'widefat', 'fixed', 'striped', $mode_class, $this->_args['plural'] );
	}

	/**
	 * Generates the table navigation above or below the table
	 *
	 * @since 3.1.0
	 * @param string $which The location of the navigation: Either 'top' or 'bottom'.
	 */
	protected function display_tablenav( $which ) {
		if ( 'top' === $which ) {
			wp_nonce_field( 'bulk-' . $this->_args['plural'] );
		}
		?>
	<div class="tablenav <?php echo esc_attr( $which ); ?>">

		<?php if ( $this->has_items() ) : ?>
		<div class="alignleft actions bulkactions">
			<?php $this->bulk_actions( $which ); ?>
		</div>
			<?php
		endif;
		$this->extra_tablenav( $which );
		$this->pagination( $which );
		?>

		<br class="clear" />
	</div>
		<?php
	}

	/**
	 * Displays extra controls between bulk actions and pagination.
	 *
	 * @since 3.1.0
	 *
	 * @param string $which
	 */
	protected function extra_tablenav( $which ) {}

	/**
	 * Generates the tbody element for the list table.
	 *
	 * @since 3.1.0
	 */
	public function display_rows_or_placeholder() {
		if ( $this->has_items() ) {
			$this->display_rows();
		} else {
			echo '<tr class="no-items"><td class="colspanchange" colspan="' . $this->get_column_count() . '">';
			$this->no_items();
			echo '</td></tr>';
		}
	}

	/**
	 * Generates the table rows.
	 *
	 * @since 3.1.0
	 */
	public function display_rows() {
		foreach ( $this->items as $item ) {
			$this->single_row( $item );
		}
	}

	/**
	 * Generates content for a single row of the table.
	 *
	 * @since 3.1.0
	 *
	 * @param object|array $item The current item
	 */
	public function single_row( $item ) {
		echo '<tr>';
		$this->single_row_columns( $item );
		echo '</tr>';
	}

	/**
	 * @param object|array $item
	 * @param string $column_name
	 */
	protected function column_default( $item, $column_name ) {}

	/**
	 * @param object|array $item
	 */
	protected function column_cb( $item ) {}

	/**
	 * Generates the columns for a single row of the table.
	 *
	 * @since 3.1.0
	 *
	 * @param object|array $item The current item.
	 */
	protected function single_row_columns( $item ) {
		list( $columns, $hidden, $sortable, $primary ) = $this->get_column_info();

		foreach ( $columns as $column_name => $column_display_name ) {
			$classes = "$column_name column-$column_name";
			if ( $primary === $column_name ) {
				$classes .= ' has-row-actions column-primary';
			}

			if ( in_array( $column_name, $hidden, true ) ) {
				$classes .= ' hidden';
			}

			/*
			 * Comments column uses HTML in the display name with screen reader text.
			 * Strip tags to get closer to a user-friendly string.
			 */
			$data = 'data-colname="' . esc_attr( wp_strip_all_tags( $column_display_name ) ) . '"';

			$attributes = "class='$classes' $data";

			if ( 'cb' === $column_name ) {
				echo '<th scope="row" class="check-column">';
				echo $this->column_cb( $item );
				echo '</th>';
			} elseif ( method_exists( $this, '_column_' . $column_name ) ) {
				echo call_user_func(
					array( $this, '_column_' . $column_name ),
					$item,
					$classes,
					$data,
					$primary
				);
			} elseif ( method_exists( $this, 'column_' . $column_name ) ) {
				echo "<td $attributes>";
				echo call_user_func( array( $this, 'column_' . $column_name ), $item );
				echo $this->handle_row_actions( $item, $column_name, $primary );
				echo '</td>';
			} else {
				echo "<td $attributes>";
				echo $this->column_default( $item, $column_name );
				echo $this->handle_row_actions( $item, $column_name, $primary );
				echo '</td>';
			}
		}
	}

	/**
	 * Generates and display row actions links for the list table.
	 *
	 * @since 4.3.0
	 *
	 * @param object|array $item        The item being acted upon.
	 * @param string       $column_name Current column name.
	 * @param string       $primary     Primary column name.
	 * @return string The row actions HTML, or an empty string
	 *                if the current column is not the primary column.
	 */
	protected function handle_row_actions( $item, $column_name, $primary ) {
		return $column_name === $primary ? '<button type="button" class="toggle-row"><span class="screen-reader-text">' .
			/* translators: Hidden accessibility text. */
			__( 'Show more details' ) .
		'</span></button>' : '';
	}

	/**
	 * Handles an incoming ajax request (called from admin-ajax.php)
	 *
	 * @since 3.1.0
	 */
	public function ajax_response() {
		$this->prepare_items();

		ob_start();
		if ( ! empty( $_REQUEST['no_placeholder'] ) ) {
			$this->display_rows();
		} else {
			$this->display_rows_or_placeholder();
		}

		$rows = ob_get_clean();

		$response = array( 'rows' => $rows );

		if ( isset( $this->_pagination_args['total_items'] ) ) {
			$response['total_items_i18n'] = sprintf(
				/* translators: Number of items. */
				_n( '%s item', '%s items', $this->_pagination_args['total_items'] ),
				number_format_i18n( $this->_pagination_args['total_items'] )
			);
		}
		if ( isset( $this->_pagination_args['total_pages'] ) ) {
			$response['total_pages']      = $this->_pagination_args['total_pages'];
			$response['total_pages_i18n'] = number_format_i18n( $this->_pagination_args['total_pages'] );
		}

		die( wp_json_encode( $response ) );
	}

	/**
	 * Sends required variables to JavaScript land.
	 *
	 * @since 3.1.0
	 */
	public function _js_vars() {
		$args = array(
			'class'  => get_class( $this ),
			'screen' => array(
				'id'   => $this->screen->id,
				'base' => $this->screen->base,
			),
		);

		printf( "<script type='text/javascript'>list_args = %s;</script>\n", wp_json_encode( $args ) );
	}
}

Changelog

VersionDescription
3.1.0Introduced.

User Contributed Notes

  1. Skip to note 2 content

    Using within Meta Boxes

    Attention when using the WP_List_Table class within a Meta Box:

    If you don’t set $this->_column_headers in your own class within prepare_items() (like shown in the code block below), then the complete and will disappear!

    $this->_column_headers = array( 
    	 $this->get_columns(),		// columns
    	 array(),			// hidden
    	 $this->get_sortable_columns(),	// sortable
    );

    Why This Happens

    If you don’t set $this->_column_headers; manually in the extending class, then the sortable columns are set up by the parent class and the $this->get_columns(); function.

    Unfortunately, when this happens your column headers array is empty – even if you set it up with get_columns(); from your child class.

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