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App Container

ExpressoTS leverages InversifyJS for its Inversion of Control (IoC) container capabilities, providing a robust system for dependency injection. This type-aware container facilitates object instantiation, resolution, and life cycle management, enabling the creation of complex dependencies with minimal code.

The AppContainer wrapper simplifies integration, allowing for straightforward registration of controllers, use cases, and providers within the application.

Configuring the container​

The application container can be customized with default scopes for dependency binding and options to skip base class checks, enhancing flexibility in dependency management.

  • defaultScope: The default scope, RequestScope, creates a new instance of a dependency for each request, while SingletonScope creates a single instance shared across all requests. The TransientScope creates a new instance each time the dependency is requested.
  • skipBaseClassChecks: When set to true, the container will skip base class checks when working with derived classes.
  • autoBindInjectable: When set to true, the container will automatically inject classes that are not explicitly bound.

Here is the interface options definition:

interface ContainerOptions {
    /**
     * The default scope for bindings in the container.
     * It can be set to Request (default), Singleton, or Transient.
     */
    defaultScope?: interfaces.BindingScope;

    /**
     * Allows skipping of base class checks when working with derived classes.
     */
    skipBaseClassChecks?: boolean;

    /**
     * Allows auto-injection of classes that are not explicitly bound to the container.
     */
    autoBindInjectable: false;
}

Creating the container

// Adding options to the container
export const appContainer: AppContainer = new AppContainer({
    defaultScope: BindingScopeEnum.Singleton,
    skipBaseClassChecks: true,
    autoBindInjectable: false,
});

// Creating a container module manager
const container = appContainer.create([
    // Add your modules here
    AppModule,
]);

export { container };

Defining the container scope​

As mentioned above, if the defaultScope option is not provided, it defaults to RequestScope. However, it is possible to change the default scope by passing the defaultScope as a an option in the container constructor. The BindingScopeEnum contains the following values:

  • BindingScopeEnum.Singleton - The dependency will be created once and will be shared across all requests.
  • BindingScopeEnum.Request - The dependency will be created once per request.
  • BindingScopeEnum.Transient - The dependency will be created every time it is requested.

Viewing container bindings​

The container can be used to view all the bindings that have been registered. This can be useful for debugging purposes or to understand the dependencies that have been registered.

appContainer.viewContainerBindings();

Container Bindings View

Registering Modules​

The appContainer facilitates module registration via its create([]) method, which accepts an array of modules. This streamlined approach reduces setup complexity and aligns with ExpressoTS's goal of simplifying application architecture:

// Create a new container
const appContainer: AppContainer = new AppContainer();

const container: Container = appContainer.create([
    // Register all the modules
    UserModule,
    PaymentModule,
    ProductModule,
]);

The use of appContainer abstracts away the intricacies of InversifyJS direct usage, providing a straightforward path to integrating and managing modules within ExpressoTS applications.

Support the Project​

ExpressoTS is an MIT-licensed open source project. It's an independent project with ongoing development made possible thanks to your support. If you'd like to help, please consider: