WordPress at a glance
filter is not described

pre_(field) filter-hook . WP 2.3.0

Filters the value of a specific post field before saving.

The dynamic portion of the hook name, $field, refers to the post field name.

Usage

add_filter( 'pre_(field)', 'filter_function_name_2249' );
function filter_function_name_2249( $value ){
	// filter...

	return $value;
}
$value(mixed)
Value of the post field.

Where the hook is called

sanitize_post_field()
sanitize_bookmark_field()
sanitize_user_field()
wp-includes/post.php 2207
$value = apply_filters( "pre_{$field}", $value );
wp-includes/bookmark.php 395
$value = apply_filters( "pre_{$field}", $value );
wp-includes/user.php 1212
$value = apply_filters( "pre_{$field}", $value );

Where the hook is used (in WP core)

wp-includes/class-wp-customize-widgets.php 1914
add_filter( 'pre_update_option', array( $this, 'capture_filter_pre_update_option' ), 10, 3 );
wp-includes/class-wp-customize-widgets.php 1933
add_filter( "pre_option_{$option_name}", array( $this, 'capture_filter_pre_get_option' ) );
wp-includes/class-wp-customize-widgets.php 1972
remove_filter( 'pre_update_option', array( $this, 'capture_filter_pre_update_option' ), 10 );
wp-includes/class-wp-customize-widgets.php 1975
remove_filter( "pre_option_{$option_name}", array( $this, 'capture_filter_pre_get_option' ) );
wp-includes/default-filters.php 77
add_filter( 'pre_term_slug', 'sanitize_title' );
wp-includes/default-filters.php 86
add_filter( 'pre_post_mime_type', 'sanitize_mime_type' );
wp-includes/default-filters.php 234
add_filter( 'pre_kses', 'wp_pre_kses_less_than' );
wp-includes/default-filters.php 238
add_filter( 'pre_comment_content', 'wp_rel_nofollow', 15 );
wp-includes/default-filters.php 390
add_filter( 'pre_option_gmt_offset','wp_timezone_override_offset' );
wp-includes/default-filters.php 400
add_filter( 'pre_option_embed_autourls', '__return_true' );
wp-includes/default-filters.php 562
add_filter( 'pre_oembed_result', 'wp_filter_pre_oembed_result', 10, 3 );
wp-includes/class-wp-customize-setting.php 364
add_filter( "pre_option_{$id_base}", array( $this, '_preview_filter' ) );
wp-includes/kses.php 1708
add_filter( 'pre_comment_content', 'wp_filter_post_kses' );
wp-includes/kses.php 1710
add_filter( 'pre_comment_content', 'wp_filter_kses' );
wp-includes/kses.php 1735
remove_filter( 'pre_comment_content', 'wp_filter_post_kses' );
wp-includes/kses.php 1736
remove_filter( 'pre_comment_content', 'wp_filter_kses' );
wp-includes/class-wp-customize-manager.php 676
add_filter( 'pre_option_current_theme', array( $this, 'current_theme' ) );
wp-includes/class-wp-customize-manager.php 679
add_filter( 'pre_option_stylesheet', array( $this, 'get_stylesheet' ) );
wp-includes/class-wp-customize-manager.php 680
add_filter( 'pre_option_template', array( $this, 'get_template' ) );
wp-includes/class-wp-customize-manager.php 683
add_filter( 'pre_option_stylesheet_root', array( $this, 'get_stylesheet_root' ) );
wp-includes/class-wp-customize-manager.php 684
add_filter( 'pre_option_template_root', array( $this, 'get_template_root' ) );
wp-includes/class-wp-customize-manager.php 714
remove_filter( 'pre_option_current_theme', array( $this, 'current_theme' ) );
wp-includes/class-wp-customize-manager.php 717
remove_filter( 'pre_option_stylesheet', array( $this, 'get_stylesheet' ) );
wp-includes/class-wp-customize-manager.php 718
remove_filter( 'pre_option_template', array( $this, 'get_template' ) );
wp-includes/class-wp-customize-manager.php 721
remove_filter( 'pre_option_stylesheet_root', array( $this, 'get_stylesheet_root' ) );
wp-includes/class-wp-customize-manager.php 722
remove_filter( 'pre_option_template_root', array( $this, 'get_template_root' ) );
wp-admin/options-discussion.php 259
add_filter( 'pre_option_show_avatars', '__return_true', 100 );
wp-admin/options-discussion.php 269
remove_filter( 'pre_option_show_avatars', '__return_true', 100 );
wp-admin/includes/bookmark.php 306
add_filter( 'pre_option_link_manager_enabled', '__return_true', 100 );
wp-admin/includes/bookmark.php 308
remove_filter( 'pre_option_link_manager_enabled', '__return_true', 100 );