如何在wp中更新自定义用户元字段？

update_user_meta( 1, 'custom_field', 'new_value' );

function set_custom_field_on_register( $user_id ) {
    update_user_meta( $user_id, 'custom_field', 'initial_value' );
}
add_action( 'user_register', 'set_custom_field_on_register' );

function add_custom_field_to_profile( $user ) {
    $custom_field_value = get_user_meta( $user->ID, 'custom_field', true );
    ?>
    <h3>Custom Field</h3>
    <table class="form-table">
        <tr>
            <th><label for="custom_field">Custom Field</label></th>
            <td>
                <input type="text" name="custom_field" id="custom_field" value="<?php echo esc_attr( $custom_field_value ); ?>" class="regular-text" />
            </td>
        </tr>
    </table>
    <?php
}
add_action( 'show_user_profile', 'add_custom_field_to_profile' );
add_action( 'edit_user_profile', 'add_custom_field_to_profile' );

function save_custom_field_on_profile_update( $user_id ) {
    if ( current_user_can( 'edit_user', $user_id ) ) {
        update_user_meta( $user_id, 'custom_field', $_POST['custom_field'] );
    }
}
add_action( 'personal_options_update', 'save_custom_field_on_profile_update' );
add_action( 'edit_user_profile_update', 'save_custom_field_on_profile_update' );