Getting Started

Installation#

Installation can be only done using a package manager and it can only be used in typescript codebase.

Using npm

npm install tiny-injector

Using yarn

yarn add tiny-injector

Configuration#

include these options in tsconfig.json

"target": "ES2016" // or higer,
"experimentalDecorators": true,
"emitDecoratorMetadata": true,

Example#

Abstract class that defines simple method to log information and errors.

abstract class Logger {
	abstract debug(...objects: any[]): void;
	abstract error(error: Error): void;
}

This abstract class is implemented by two concrete types

import { Injector, Injectable } from "tiny-injector";

@Injectable()
class FileLogger extends Logger {
	debug(...objects: any[]) {
		// write to debug file
	}

	error(error: Error) {
		// write to error file
	}
}

@Injectable()
class ConsoleLogger extends Logger {
	debug(...objects: any[]) {
		console.log("DEBUG", new Date().toString());
		console.log(...objects);
	}

	error(error: Error) {
		console.error(error);
	}
}

The sample code register the abstract Logger service with the concrete type FileLogger in production and ConsoleLogger otherwise. The AddSingleton method registers the service with a Singleton lifetime.

if (process.env.NODE_ENV === "production") {
	Injector.AddSingleton(Logger, FileLogger);
} else {
	Injector.AddSingleton(Logger, ConsoleLogger);
}

in this sample, the abstract Logger is injected in DataProvider constructor. the injector is registering the DataProvider first, then locating it to execute the fetchData method.

@Injectable()
class DataProvider {
	constructor(private logger: Logger) {
		logger.debug("DataProvider");
	}

	async fetchData() {
		try {
			return await fetch(".../data");
		} catch (error) {
			this.logger.error(error);
		}
	}
}

Injector.AddSingleton(DataProvider);

const dataProvider = Injector.GetRequiredService(DataProvider);
dataProvider.fetchData();

as you can see we provided two arguments when adding the abstract Logger service and only one argument when adding the DataProvider service, because DataProvider doesn't have abstraction.