Optional Dependencies

You can declare an optional dependency using the standard TypeScript syntax:

ApiService.ts

import { injected } from 'brandi';

import { TOKENS } from './tokens';

import { Logger } from './Logger';

export class ApiService {

/* ↓ The optional dependency. */

constructor(private logger?: Logger) {}

}

And inject it using the optional token field:

ApiService.ts

injected(

ApiService,

TOKENS.logger.optional /* ← The optional dependency token. */,

);

When using optional tokens, the Brani container will not throw an error if the dependency is not bound in the container, but will return undefined.