Container

The Webdoc service container is a simple tool for managing class dependencies and performing dependency injection.

Installation

npm install @webdocgroup/container

Usage

Simple Bindings

Use bind to register a factory function. The factory is called every time you resolve the key, returning a new instance each time.

type Application = {
    'command.createUser': CreateUserHandler;
    'query.getUser': GetUserQueryHandler;
    userRepository: UserRepository;
};

const container = new Container<Application>();

// Register a factory for 'command.createUser'.
// Each call to resolve will create a new instance.
container.bind('command.createUser', () => new CreateUserHandler());

// Resolving returns a new instance every time.
const handler = container.resolve('command.createUser');

Binding Singletons

Use singleton to register a factory that is only called once. All future resolves return the same instance.

type Application = {
    'command.createUser': CreateUserHandler;
    'query.getUser': GetUserQueryHandler;
    userRepository: UserRepository;
};

const container = new Container<Application>();

// Register a singleton factory for 'userRepository'.
// Only one instance will ever be created and reused.
container.singleton('userRepository', () => new UserRepository());

// Factories can resolve other dependencies from the container.
container.bind(
    'query.getUser',
    () =>
        new GetUserHandler({
            userRepository: container.resolve('userRepository'),
        })
);