This library should make it easier to facilitate a Service layer for CodeIgniter4 application. Additionally there are some tools to interact with the model layer, in particular this library contains a Service to have some nicer and more reliable syntax for database transactions.

You can add this library to your project using composer:

composer require mkuettel/codeigniter4-services

That's it, but you might want to change some of the configuration, as described in the next section.

There are multiple configuration files available in the src/Config directories. You can override these default configuration by copying the configuration file into your project and adjusting the values in your editor.

TODO: add publishable configuration

This Library provides the interface \MKU\Services\Service.

The idea is that you extend from this interface by defining another interface for your own service. In this interface you define all the methods your service will have:

use \MKU\Services\Service;

interface MyBusinessService extends Service {
    public function placeOrder(Order $order): Result;
    public function sendOrderConfirmationMail(Order $order): Result;
    // ...
}

You then implement this interface with your own service class.

class SimpleBusinessService extends MyBusinessService {
    
    private OrderModel $orderModel;
    private MailService $mailService;

    public function __construct(OrderModel $orderModel, MailService $mail) { /* ... */ }
    public function shortname(): string { return 'simple_business'; } 
    public function placeOrder(Order $order): Result { /* */ }
    public function sendOrderConfirmationMail(Order $order): Result { /* */ }
    // ...
}

You'll also need to implement shortname(): string method returning a unique identifier for this service implementation.

The shortname will later be used to get or create an instance the implementing service class using:

 service('<shortname>'); 
 \Config\Services::shortname();

But for this to work you must for now register it as follows

class Services extends BaseService {
    
    // ....
    
    // use the same parameters as required by the constructor of the service class,
    // but make them null by default.
    public function business_simple() (
        OrderModel $orderModel = null,
        MailService $mail = null,
        bool $getShared = true // add extra parameter to reuse past instance if available (e.g. a singleton instance)
    ): SimpleBusinessService {
        if ($getShared) return self::getSharedInstance('simple_business', $config, $db);
        return new SimpleBusinessService(
            $orderModel ?? model(OrderModel::class);
            $mail ?? self::mail_service(),
        );
    }
    
    // use the interface as return type here
    public function business(): MyBusinessService {
        // change which service class to use for the MyBusinessService interface here
        return self::business_simple();
    }
    
    // ....
}

TODO(so this must not be done manually): add ServiceContainer as a base class for \Config\Services which autoconfigures the services depending on their constructor types or annotations and creates the builder methods in \Config\Services.

This library provides a TransactionService, which allows you to execute a custom function during a database transaction:

// PHP 7.4+ using arrow functions
service('transaction')->transact(fn() => do_database_operation())

// Using anonymous function (or any Closure)
service('transaction')->transact(function() use ($db) {
    $db->insert( /* update */ ); ...
    $db->update( /* ...  */); ...
});

Used in this manner, the transaction service begins a transaction before executing the given closure. If an exception occurs during the transaction, the transaction will be rolled back.

Transactions can be nested.

NOTE: Not all database systems and engines support transactions by default, especially transactions with strict isolation between connections.

Future configuration options:

• strictMode: Whether to use strict transactions, meaning other connections cannot see your modifications until you commit?
• testMode: Whether to rollback the transaction on exception? tbd.
• connection_type: tbd

https://github.com/mkuettel/codeigniter4-services