CoCart Products Cache

A WordPress plugin that makes CoCart's /cocart/v2/products and /cocart/v2/products/{id} endpoints respond in under 10 ms by serving all product data from a single static JSON file — zero database queries per request.

The Problem

CoCart's default products endpoint runs live WooCommerce + database queries on every request. For stores with 50–500+ products this typically costs 200–800 ms per page load and puts unnecessary load on the database.

How It Works

The plugin intercepts the CoCart REST route before it ever reaches CoCart, using WordPress's rest_pre_dispatch filter. Requests are served directly from a pre-built JSON file stored in wp-content/uploads/.

Browser → WordPress REST API
              ↓
        rest_pre_dispatch  ← plugin intercepts here
              ↓
        Read JSON file     ← ~1–5 ms (OS file cache)
              ↓
        Return response    ← CoCart-compatible format

What never runs: WooCommerce product queries, database joins, CoCart response formatting, authentication middleware.

Features

• Zero DB queries per product request after initial build
• Both endpoints cached — collection (/products) and single (/products/{id})
• Incremental updates — only changed products are rewritten; editing one product takes ~50 ms regardless of catalog size
• Smart batching — multiple saves within 5 seconds are batched into one file operation
• Memory-safe full rebuild — chunked streaming with fwrite(), handles 10 000+ products without hitting PHP memory limits
• Category filtering in PHP — ?category=slug filters the in-memory array, no separate files or DB queries
• CoCart-native format — output is identical to CoCart's own response; no frontend changes needed
• Graceful fallback — if a product isn't cached yet, the request falls through to live CoCart

Requirements

Installation

1. Download or clone this repository
2. Copy the cocart-products-cache folder into wp-content/plugins/
3. Activate the plugin in WP Admin → Plugins
4. The cache builds automatically on activation

Or install as a single file: upload just cocart-products-cache.php to wp-content/plugins/cocart-products-cache/.

Cache Management

Automatic Updates

The cache stays in sync automatically — no manual intervention needed:

Manual Flush

Go to WP Admin → Plugins and click Flush Cache next to this plugin. This deletes the current cache file and immediately rebuilds it.

Admin Benchmark Tool

benchmark.php adds a page at WP Admin → Tools → Cache Benchmark that measures:

• Read speed at various product counts (100 / 500 / 1 000 / 2 500 / 5 000 / 10 000)
• Memory usage per request
• Write speed for full rebuild vs incremental update
• Plain-English verdict on performance at your catalog scale

Response Format

The cached response is byte-for-byte identical to CoCart's native format.

Collection — GET /wp-json/cocart/v2/products

Returns a JSON array of product objects. Response headers include:

X-WP-Total: 247
X-CoCart-Cache: HIT
X-Cache-Generated: 2025-01-15 10:30:00 UTC
Cache-Control: public, max-age=300

Single Product — GET /wp-json/cocart/v2/products/{id}

Returns a single product object.

X-CoCart-Cache: HIT
X-Cache-Generated: 2025-01-15 10:30:00 UTC

Product Object Shape

{
  "id": 42,
  "name": "Classic T-Shirt",
  "slug": "classic-t-shirt",
  "type": "simple",
  "sku": "TSH-001",
  "description": "<p>Full product description HTML</p>",
  "short_description": "<p>Short description HTML</p>",
  "featured": false,
  "prices": {
    "price": "2999",
    "regular_price": "3999",
    "sale_price": "2999",
    "on_sale": true,
    "currency": {
      "currency_code": "USD",
      "currency_symbol": "$",
      "currency_minor_unit": 2
    }
  },
  "images": [
    { "id": 101, "src": "https://example.com/wp-content/uploads/shirt.jpg", "alt": "Classic T-Shirt" }
  ],
  "categories": [
    { "id": 5, "name": "Apparel", "slug": "apparel" }
  ],
  "stock": {
    "stock_status": "instock",
    "is_in_stock": true,
    "stock_quantity": null
  },
  "weight": "",
  "dimensions": { "length": "", "width": "", "height": "" },
  "variations": [],
  "related": []
}

Prices are minor-unit integers as strings — e.g. "2999" means $29.99 when currency_minor_unit is 2. This matches CoCart's native format exactly.

Supported Query Parameters

Cache File Location

wp-content/uploads/cocart-products-cache.json

The file is written atomically (to a .tmp file, then renamed) so a partial write never corrupts a live request.

Performance

Tested on a VPS with 247 products:

Pairing With the Frontend

This plugin pairs with CoCart-API-SDK

License

GPL-2.0-or-later