Apex Dependency Injection

This repository demonstrates Apex Dependency Injection with a sample shipping service (ShippingService) that allows to generate tracking numbers.

Configuration

This sample provides two shipping service mock implementations: FedExImpl and DHLImpl.

Usage

The service can be accessed via the ShippingInjector class in two ways:

Option 1: Using the default implementation

This requires that you set the default service implementation as a Service_Implementations__mdt custom metadata record. The Shipping__c field of the custom metadata record must map to one of the ShippingService implementation class names.

// Get the implementation of the service configured in Service_Implementations__mdt.Shipping__c custom metadata
ShippingService service = ShippingInjector.getDefaultService(); 
String trackingNumber = service.generateTrackingNumber();
System.debug(trackingNumber); // => DHL-XXXX if DHLImpl is the default

Option 2: Using a specific implementation

// Get the FedEx implementation
ShippingService service = ShippingInjector.getService('FedExImpl');
String trackingNumber = service.generateTrackingNumber();
System.debug(trackingNumber); // => FEX-XXXX

Installation

1. Create a scratch org:

   sfdx force:org:create -a apex-di -s -f config/project-scratch-def.json

2. Push source to scratch org:

   sfdx force:source:push