Hooks & Filters Reference: Complete Developer Guide

Hooks & Filters Reference

Audience: Developer — Requires PHP / Laravel knowledge. Category: Technical Reference — Technical documentation for integration developers.

What You Will Learn

• Understand the Action vs Filter mechanism in PolyCMS

• Look up hook names, parameters, and dispatch locations

• Register hooks from theme functions.php and module ServiceProvider

• Use priority to control the order of execution

• Apply practical use-cases for each hook group

1. Introduction to the Hook System

PolyCMS uses a WordPress-like Hook/Filter system, built natively on Laravel:

• Action (Hook::doAction): Executes side-effects (logging, sending emails, syncing data). No return value needed.

• Filter (Hook::applyFilters): Receives a value, modifies it, and must return the modified value.

Basic Syntax

use App\Facades\Hook;

// Register an Action
Hook::addAction('order_completed', function ($order) {
    Mail::to($order->user)->send(new OrderCompletedMail($order));
}, priority: 10);

// Register a Filter
Hook::addFilter('post.default_image', function (?string $imageUrl, $post) {
    if ($post?->categories->contains('slug', 'news')) {
        return '/images/news-default.jpg';
    }
    return $imageUrl;
}, priority: 10);

2. Content & Posts

Filters

Actions

Practical Use-cases

UC1 — Category-specific default thumbnail: Keep a specific default thumbnail for each category when a post does not have a featured image:

Hook::addFilter('post.default_image', function (?string $url, $post) {
    if ($post?->categories->contains('slug', 'tech')) return '/images/defaults/tech.jpg';
    if ($post?->categories->contains('slug', 'lifestyle')) return '/images/defaults/lifestyle.jpg';
    return $url; // fallback to admin setting
});

UC2 — Wiki URL structure: Demote/change a post URL structure from /posts/slug to /docs/slug for a wiki-style layout:

Hook::addFilter('post.frontend_url', function ($url, $post) {
    return ($post->type === 'wiki') ? '/docs/' . $post->slug : $url;
});

UC3 — Auto-inject inline advertisements: Automatically insert ad banner blocks after the 3rd paragraph of a post:

Hook::addFilter('content.render.html', function (string $html) {
    $adBanner = '<div class="ad-inline">Advertisement</div>';
    $parts = explode('</p>', $html, 4);
    if (count($parts) > 3) {
        $parts[2] .= '</p>' . $adBanner;
        return implode('</p>', $parts);
    }
    return $html;
});

3. Media Library

Filters

Actions

Practical Use-cases

UC1 — CDN URL Rewriting: Integrate with Cloudflare R2 or Amazon S3, automatically converting local storage paths to CDN URLs:

Hook::addFilter('media.url', function (string $url, $media) {
    return str_replace('/storage/', 'https://cdn.mysite.com/', $url);
});

UC2 — Protect Critical System Assets: Prevent accidental deletion of any image currently in use as the site logo:

Hook::addFilter('media.delete.should', function (bool $allow, $media) {
    $logoUrl = get_option('site_logo', null, 'general');
    return ($media->url === $logoUrl) ? false : $allow;
});

UC3 — Auto-optimize Images on Upload: Dispatch background queues to generate lightweight WebP images from standard uploads:

Hook::addAction('media.uploaded', function ($media, $file) {
    if (str_starts_with($media->mime_type, 'image/')) {
        dispatch(new ConvertToWebpJob($media));
    }
});

4. E-Commerce — Orders & Refunds

Actions

Filters

Practical Use-cases

UC1 — Telegram Notification for New Orders:

Hook::addAction('order_status_updated', function ($order, $old, $new) {
    if ($old === 'pending' && $new === 'processing') {
        TelegramBot::send(" Order #{$order->code} has been confirmed!");
    }
});

UC2 — Loyalty Reward points on Order Completion:

Hook::addAction('order_completed', function ($order) {
    if ($order->user_id) {
        $points = (int) floor($order->total / 10); // 1 point per $10 spent
        LoyaltyService::addPoints($order->user_id, $points, "Order #{$order->code}");
    }
});

UC3 — Audit Logging for Failed Refunds:

Hook::addAction('order.refund.failed', function ($order, $data, $exception, $userId) {
    AuditLog::create([
        'action' => 'refund_failed',
        'order_id' => $order->id,
        'user_id' => $userId,
        'reason' => $exception->getMessage(),
    ]);
});

5. E-Commerce — Cart, Shipping, Tax, Inventory

Filters

Actions

Practical Use-cases

UC1 — Free Shipping for Orders over $100:

Hook::addFilter('shipping.calculate_cost', function ($cost, $method, $cart) {
    $subtotal = collect($cart->items)->sum(fn($i) => $i->price * $i->quantity);
    return ($subtotal >= 100) ? 0 : $cost;
});

UC2 — Block Reviews if User has Not Purchased the Product:

Hook::addFilter('review.can_submit', function (bool $allowed, $user, $product) {
    $hasPurchased = Order::where('user_id', $user->id)
        ->where('status', 'completed')
        ->whereHas('items', fn($q) => $q->where('product_id', $product->id))
        ->exists();
    return $hasPurchased;
});

UC3 — Facebook Pixel Tracking for AddToCart Event:

Hook::addAction('cart.item.added', function ($item, $cart) {
    session()->push('fb_pixel_events', [
        'event' => 'AddToCart',
        'product_id' => $item->product_id,
        'value' => $item->price,
    ]);
});

6. E-Commerce — Payment Gateways

Filters

Practical Use-case: Add a custom field to Bank Transfer gateway:

Hook::addFilter('payment.gateway.config_schema', function ($schema, $gateway) {
    if ($gateway->code === 'bank_transfer') {
        $schema['branch_code'] = [
            'type' => 'text', 'label' => 'Branch Code', 'required' => false,
        ];
    }
    return $schema;
});

7. Theme & Appearance

Filters

Actions

Practical Use-cases

UC1 — Inject Promo Banner from a Module:

Hook::addFilter('frontend.topbar.banners', function (array $banners) {
    $banners[] = [
        'text' => ' Flash Sale — 30% Off Today!',
        'url' => '/sale',
        'bg_color' => '#ff4444',
    ];
    return $banners;
});

UC2 — Google Analytics Head Injection:

Hook::addAction('cms_head', function () {
    $ga = get_option('google_analytics_id', null, 'seo');
    if ($ga) {
        echo "<script async src='https://www.googletagmanager.com/gtag/js?id={$ga}'></script>";
    }
});

UC3 — Load Popular Posts Sidebar Variable:

Hook::addFilter('theme.view.data', function ($data, $viewName) {
    if ($viewName === 'posts.index') {
        $data['popular_posts'] = Post::orderBy('views', 'desc')->limit(5)->get();
    }
    return $data;
});

8. Settings & Configuration

Filters

Actions

Practical Use-cases

UC1 — Register Custom Settings Section via Module:

Hook::addFilter('settings.defaults', function ($defaults) {
    $defaults['mymodule'] = [
        'mymodule_api_key' => [
            'key' => 'mymodule_api_key', 'value' => '', 'type' => 'text',
            'label' => 'API Key', 'description' => 'Enter your API key',
        ],
    ];
    return $defaults;
});

UC2 — Clear Route Cache on Permalinks Update:

Hook::addAction('settings.saved', function ($payload) {
    if (($payload['group'] ?? '') === 'permalinks') {
        Artisan::call('route:clear');
        Cache::tags('routes')->flush();
    }
});

9. Users, Roles & Auth

Filters

Actions

Practical Use-cases

UC1 — Multi-Factor Authentication Interceptor:

Hook::addFilter('auth.login.pre_token', function ($response, $user, $request) {
    if ($user->hasRole('admin') && !$request->filled('otp_code')) {
        return response()->json(['requires_2fa' => true, 'user_id' => $user->id], 403);
    }
    return $response; // null = continue token generation
});

UC2 — Welcome Email on User Signup:

Hook::addAction('user.creating', function ($data) {
    dispatch(new SendWelcomeEmail($data['email'], $data['name']));
});

10. SEO

Filters

Practical Use-case — Canonical URL for Multilingual setups:

Hook::addFilter('seo.canonical_url', function (string $url) {
    $locale = app()->getLocale();
    if ($locale !== 'en') {
        return url("/{$locale}" . parse_url($url, PHP_URL_PATH));
    }
    return $url;
});

11. Widgets

Filters

Actions

Practical Use-case — Register a "Store Map" widget type:

Hook::addAction('widgets.register_types', function ($manager) {
    $manager->registerType('store_map', [
        'label' => 'Store Map',
        'description' => 'Google Maps showing store locations',
        'fields' => [
            'api_key' => ['type' => 'text', 'label' => 'Google Maps API Key'],
            'lat' => ['type' => 'text', 'label' => 'Latitude'],
            'lng' => ['type' => 'text', 'label' => 'Longitude'],
        ],
        'view' => 'widgets.store-map',
    ]);
});

12. Admin Navigation & Editor

Filters

Actions

Practical Use-case — Add custom SEO status menu item to top bar:

Hook::addFilter('topbar.menu.items', function (array $items, $request, $user) {
    $items[] = [
        'key' => 'seo_score',
        'label' => 'SEO Score',
        'icon' => 'chart-bar',
        'url' => '/admin/seo/score',
        'position' => 50,
    ];
    return $items;
});

13. Modules

Filters

Actions

Practical Use-case — Auto-run migrations on module activation:

Hook::addAction('module.activating', function ($moduleKey, $module) {
    Artisan::call('migrate', [
        '--path' => "modules/Polyx/{$moduleKey}/database/migrations",
        '--force' => true,
    ]);
});

14. System Bootstrap

Actions

Practical Use-case — Module registers custom capabilities/permissions:

Hook::addAction('roles.register_permissions', function ($registry) {
    $registry->register('manage analytics', 'Analytics', 'View and manage analytics dashboard');
    $registry->register('export reports', 'Analytics', 'Export analytics reports to CSV');
});

Related Articles

• Hooks & Filters Overview — Event system general overview

• Theme Development — Getting started with custom themes

• Module Development — Getting started with custom modules

• REST API Authentication — Authenticating API clients