Creates an HTML dropdown (<option> elements) for hierarchical pages.

Since: 2.1.0
Source: wp-includes/class-walker-page-dropdown.php
Used by: wp_dropdown_pages()

Class Synopsis

class Walker_PageDropdown extends Walker {
    public $tree_type = 'page';
    public $db_fields = [
        'parent' => 'post_parent',
        'id'     => 'ID',
    ];
    
    public function start_el( &$output, $data_object, $depth = 0, $args = [], $current_object_id = 0 );
}

Configuration

$db_fields

public $db_fields = [
    'parent' => 'post_parent',  // WP_Post->post_parent
    'id'     => 'ID',           // WP_Post->ID
];

Methods

start_el()

Outputs a single <option> element for a page.

public function start_el( &$output, $data_object, $depth = 0, $args = [], $current_object_id = 0 )

Args used:

• selected — Page ID to mark as selected
• value_field — Post field for option value (default: 'ID')

Output:

<option class="level-0" value="2">About Us</option>
<option class="level-1" value="5">&nbsp;&nbsp;&nbsp;Our Team</option>
<option class="level-1" value="7" selected="selected">&nbsp;&nbsp;&nbsp;Contact</option>

No List Methods

This walker only implements start_el(). Dropdowns don’t need container methods.

Depth Indication

Hierarchy is shown through   padding:

• Depth 0: No padding
• Depth 1: 3   characters
• Depth n: n * 3   characters

Empty Title Handling

Pages without titles display as:

#123 (no title)

Usage Example

// Direct usage
$walker = new Walker_PageDropdown();
$pages = get_pages( [
    'sort_column' => 'menu_order',
] );

echo '<select name="page_id">';
echo '<option value="">Select a page</option>';
echo $walker->walk( $pages, 0, [
    'selected'    => get_the_ID(),
    'value_field' => 'ID',
] );
echo '</select>';

// Via wp_dropdown_pages()
wp_dropdown_pages( [
    'name'              => 'parent_page',
    'show_option_none'  => '(no parent)',
    'option_none_value' => '0',
    'selected'          => $post->post_parent,
] );

Custom Value Field

The value_field argument lets you change what’s used for the option value:

// Use post_name (slug)
wp_dropdown_pages( [
    'value_field' => 'post_name',
] );
// Output: <option value="about-us">About Us</option>

// Use ID (default)
wp_dropdown_pages( [
    'value_field' => 'ID',
] );
// Output: <option value="2">About Us</option>

Extending

class My_Page_Dropdown extends Walker_PageDropdown {
    public function start_el( &$output, $page, $depth = 0, $args = [], $current = 0 ) {
        $pad = str_repeat( '— ', $depth );  // Use dashes instead of spaces
        
        $title = $page->post_title ?: sprintf( '#%d (no title)', $page->ID );
        
        $output .= sprintf(
            '<option value="%d"%s data-template="%s">%s%s</option>',
            $page->ID,
            selected( $args['selected'], $page->ID, false ),
            esc_attr( get_page_template_slug( $page->ID ) ),
            $pad,
            esc_html( $title )
        );
    }
}

Related

• wp_dropdown_pages() — Main function using this walker
• Walker_Page — List version
• list_pages filter — Modify page title in dropdown