Extension File Structure

Understand the required directory structure and file organization for OpenCart extensions

Overview

OpenCart 4.x extensions follow a standardized directory structure under extension/{vendor}/. Each extension contains separate directories for admin, catalog, and system files.

Directory Structure

extension/{vendor}/
├── admin/
│   ├── controller/{type}/{name}.php
│   ├── model/{type}/{name}.php
│   ├── view/
│   │   └── template/{type}/{name}.twig
│   └── language/
│       └── en-gb/{type}/{name}.php
├── catalog/
│   ├── controller/{type}/{name}.php
│   ├── model/{type}/{name}.php
│   ├── view/
│   │   └── template/{type}/{name}.twig
│   └── language/
│       └── en-gb/{type}/{name}.php
├── system/
│   ├── library/{name}.php
│   └── config/{name}.php
└── install.json

Extension Types

Type	Purpose	Example
payment	Payment gateways	PayPal, Stripe
shipping	Shipping methods	Flat rate, UPS
module	Content modules	Featured products, banners
total	Order total calculations	Tax, shipping, discounts
theme	Store themes	Custom designs
fraud	Fraud detection	IP blocking, max orders
captcha	CAPTCHA systems	reCAPTCHA, Basic CAPTCHA
currency	Currency converters	ECB, Fixer.io
report	Reporting tools	Sales reports, analytics

File Naming Conventions

Namespace Pattern

Opencart\{Application}\Controller\Extension\{Vendor}\{Type}\{Name}

Examples

# Payment Extension
Vendor: opencart
Type: payment
Name: bank_transfer

Admin Controller:
  Path: extension/opencart/admin/controller/payment/bank_transfer.php
  Namespace: Opencart\Admin\Controller\Extension\Opencart\Payment
  Class: BankTransfer

Catalog Controller:
  Path: extension/opencart/catalog/controller/payment/bank_transfer.php
  Namespace: Opencart\Catalog\Controller\Extension\Opencart\Payment
  Class: BankTransfer

Extension Metadata

install.json

Every extension should include install.json:

{
    "name": "My Extension",
    "version": "1.0.0",
    "author": "Your Name",
    "link": "https://example.com",
    "type": "payment",
    "license": {
        "type": "MIT",
        "url": "https://opensource.org/licenses/MIT"
    }
}

Example: Payment Extension

Complete file structure for a payment gateway:

extension/myvendor/
├── admin/
│   ├── controller/
│   │   └── payment/
│   │       └── mypayment.php
│   ├── language/
│   │   └── en-gb/
│   │       └── payment/
│   │           └── mypayment.php
│   └── view/
│       └── template/
│           └── payment/
│               └── mypayment.twig
├── catalog/
│   ├── controller/
│   │   └── payment/
│   │       └── mypayment.php
│   └── language/
│       └── en-gb/
│           └── payment/
│               └── mypayment.php
└── install.json

Routing

Extensions are accessed via extended routes:

extension/{vendor}/{type}/{name}
extension/{vendor}/{type}/{name}.{method}

Examples:

extension/opencart/payment/bank_transfer
extension/opencart/payment/bank_transfer.confirm

Next Steps

Creating Modules

Build custom modules

Payment Gateways

Develop payment extensions

Shipping Methods

Create shipping methods

Event System

Use events in extensions