Dependency injection

Dependency injection (DI) in Optimizely Configured Commerce is based on the DI framework in ASP.NET Core located in the Microsoft.Extensions.DependencyInjection API.

Configured Commerce uses Grace for .NET Core 6.0 and above and Unity for .NET 4.8 by default. The container registration process starts in the BootStrapper, which is called from the SiteStartup.cs class in .NET 4.8 and the UseCommerce extension method in .NET Core.

You can register a class in the IOC container by adding an IDependency and an IExtension interface. This allows the DependencyRegistrar class to find and register the class at startup. The DependencyRegistrar class goes through the app domain assemblies and registers all implementations that it finds with these interfaces.

The default lifetime is per request. You can change the timeline to singleton or transient lifetime by adding an ISingletonLifetime or ITransientLifetime interface to the dependency.

You can register multiple implementations for a single interface by adding the IMultiInstanceDependency interface to the implementation. This automatically uses the class name as the registration name. Alternatively, you can use the DependencyName attribute to register under a custom name.

You can add attributes to the dependency implementation to change its behavior:

You should use dependency injection through constructors. You can either set the dependency directly as a parameter in the constructor or set IDependencyLocator as a parameter and use the methods on that interface to get dependencies.

You can get dependencies in .NET Core through context such as HttpContext.RequestServices.

Named registrations should have a factory with a IDependencyLocator injected which can do the resolution by name.