Advanced 404-page snippet for WordPress

This PHP code is designed to handle custom 404 errors in a WordPress environment. Its main purpose is to improve the user experience by attempting to redirect users to the most relevant page or provide helpful suggestions if a requested URL cannot be found. Here's a detailed breakdown of what the code does:

Key Features:

1. Extract the Last Segment of the URL:

• The script retrieves the requested URL and isolates the last part of the path (e.g., for /some/path/example, it extracts example).

2. Search for Existing Paths:

• A function (find_existing_path) is used to check whether the extracted segment matches:

-- A published post slug.
-- A tag slug in the WordPress taxonomy.

• If a match is found, the function returns the URL of the corresponding post or tag.
• If no match is found in the primary database search, it checks a predefined list of folders (blog, category, etc.) for potential matches. If a match exists, it constructs and returns the appropriate URL.

3. Redirect to the Found Path:

• If a matching path is found in the search process, the user is redirected to it using a 301 permanent redirect.

4. Search for Similar Content:

• If no exact match is found, the script converts the last segment into a search query by replacing special characters (-, _, and %20) with +.
• It performs a WordPress search query to find up to 5 posts that might be relevant.

5. Display Search Results:

• If matching posts are found, it displays them to the user in the following way: -- A heading is shown in the appropriate language (Russian, Italian, or English), depending on the site's locale. -- Instead of plain links, the thumbnails of the suggested posts are displayed using a loop (get_template_part).

6. Fallback:

• If neither a matching path nor search results are found, the standard 404 error page will remain.

Purpose:

This script enhances WordPress’s default 404 error handling by:

• Redirecting users to relevant pages if possible.
• Providing search-based suggestions when exact matches are unavailable.
• Improving user navigation and potentially reducing bounce rates.

`
function handle_custom_404() {
// Get the requested URL path
$request_uri = $_SERVER['REQUEST_URI'];
$request_path = trim(urldecode($request_uri), '/');

// Extract only the last segment of the path
$last_segment = basename($request_path);

// Function to search for an existing path in other folders
function find_existing_path($path) {
    global $wpdb;

    // Perform a combined query to search for slugs in posts and tags without a LIMIT 1 restriction
    $results = $wpdb->get_results($wpdb->prepare(
        "(SELECT ID AS item_id, 'post' AS item_type FROM {$wpdb->posts} 
          WHERE post_name = %s AND post_status = 'publish')
        UNION ALL
        (SELECT t.term_id AS item_id, 'tag' AS item_type FROM {$wpdb->terms} t
          INNER JOIN {$wpdb->term_taxonomy} tt ON t.term_id = tt.term_id
          WHERE t.slug = %s AND tt.taxonomy = 'post_tag')",
        $path, $path
    ));

    // If exactly one record is found, return its URL
    if (count($results) === 1) {
        $result = $results[0];
        if ($result->item_type === 'post') {
            return get_permalink($result->item_id);
        } elseif ($result->item_type === 'tag') {
            return get_tag_link($result->item_id);
        }
    }

    // If multiple results or none are found, use the old logic
    $paths_to_check = ['blog', 'category', 'news', 'tag', 'news/news-photo'];

    foreach ($paths_to_check as $folder) {
        $potential_path = $folder . '/' . $path;

        // Check if a page exists at this path or a term exists in the required taxonomy
        if (url_to_postid(site_url($potential_path)) != 0 || term_exists($path, $folder)) {
            return site_url($potential_path);
        }
    }

    return false;
}

// Check if a similar path exists in other folders
$existing_path = find_existing_path($last_segment);

if ($existing_path) {
    // If a similar path is found, perform a redirect
    wp_redirect($existing_path, 301);
    exit;
}

// Search by keywords, replacing "-" and "_" with pluses
$search_query = str_replace(['-', '_', '%20'], '+', $last_segment);

// Perform a search by keywords
$search = new WP_Query([
    's' => $search_query,
    'posts_per_page' => 5
]);

// Output results if found
if ($search->have_posts()) {
    echo '</br>';

    $locale = get_locale();
    if ($locale === 'ru_RU') {
        echo '<h2>Возможно Вы искали это:</h2>';
    } elseif ($locale === 'it_IT') {
        echo '<h2>Forse stavi cercando questo:</h2>';
    } else {
        echo '<h2>Perhaps you were looking for this:</h2>';
    }
    echo '</br>';
    echo '<div>';
    // Instead of displaying links, output post thumbnails
    while ($search->have_posts()) : 
        $search->the_post();
        echo '<div class="post-thumbnail">';
        get_template_part('content', get_post_format());
        echo '</div>';
    endwhile;

    // Output pagination
    // the_posts_pagination();

    echo '</div>';
    wp_reset_postdata();
}

}

`

This code on GitHub

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