acp-filtering-dropdown_args.php

<?php
/**
 * This filter allows you to alter the filtering drop down arguments
 */

/**
 * Usage of the hook
 *
 * @param array     $args
 * @param AC\Column $column
 *
 * @return array
 */
function acp_filtering_dropdown_args_usage($args, AC\Column $column)
{
    // Example usage:

    // Set to `true` when the options must be sorted alphabetically
    // $args['order'] = true;

    // Use to modify the available filter options
    // $args['options'][ $key ] = $label;

    // Hide the `empty` and `non empty` options
    // $args['empty_option'] = false;

    // Limit the number of items in the dropdown
    // $args['limit'] = 1000;

    return $args;
}

add_filter('acp/filtering/dropdown_args', 'acp_filtering_dropdown_args_usage', 10, 2);

/**
 * Remove the empty options for the Custom Field column
 *
 * @param array     $args
 * @param AC\Column $column
 *
 * @return array
 */
function acp_filtering_remove_empty_option_for_custom_field_column($args, AC\Column $column)
{
    $column_type = 'column-meta'; // Custom Field Column type

    if ($column_type === $column->get_type()) {
        if (isset($args['empty_option'])) {
            unset($args['empty_option']);
        }
    }

    return $args;
}

add_filter('acp/filtering/dropdown_args', 'acp_filtering_remove_empty_option_for_custom_field_column', 10, 2);

/**
 * @param array     $args
 * @param AC\Column $column
 *
 * @return array
 */
function acp_filter_format_options_as_currency($args)
{
    foreach ($args['options'] as $value => $label) {
        $args['options'][$value] = sprintf('$ %s,00', $label);
    }

    return $args;
}

add_filter('acp/filtering/dropdown_args', 'acp_filter_format_options_as_currency', 10, 1);

/**
 * @param array     $args
 * @param AC\Column $column
 *
 * @return array
 */
function acp_filter_format_unserialize_options($args, AC\Column $column)
{
    if ($column instanceof AC\Column\CustomField && 'key_to_alter_options' === $column->get_meta_key()) {
        foreach ($args['options'] as $value => $label) {
            $args['options'][$value] = implode(', ', unserialize($label));
        }
    }

    return $args;
}

add_filter('acp/filtering/dropdown_args', 'acp_filter_format_unserialize_options', 10, 2);