Dymexjs/DI

Dymexjs stands for DYnamic, Modular, EXtensible JavaScript/Typescript framework.

A dependency injection library for Typescript/Javascript to help build well-structured code and easily testable applications.

Dymexjs/DI performs Constructor Injection on the constructors of decorated classes or classes with the properties STATIC_INJECTIONS and STATIC_INJECTION_LIFETIME, but also allows for injection into class fields, accessor's, methods and getter's.

• Dymexjs/DI
  • Instalation
  • Basic Usage
    • Direct to container
    • Decorators
      • Available Decorators
    • Static Injection (without decorators)
    • Lifetime
    • Register
    • Resolution
    • Child Containers and Scopes
    • Cleaning
  • Circular Dependencies
  • Documentation
  • Code of Conduct
  • How to Contribute
  • License 📝
  • Contributors ✨

Instalation

npm install --save @dymexjs/di

Basic Usage

Direct to container

import { container } from "@dymexjs/di";

class TestService {
  printMessage() {
    return "I'm printting this message inside of TestService instance.";
  }
}

class Test {
  constructor(public testService: TestService) {}
}

container.registerSingleton(Test, Test, [TestService]);
// or for ex: container.registerSingleton("test", Test, [TestService]);

//and in another place after the registration
const testInstance = container.resolve(Test);
// or: const testInstance = container.resolve("test");

console.log(testInstance.testService.printMessage());
// logs "I'm printting this message inside of TestService instance."

More info here Register

Decorators

import { container } from "@dymexjs/di";

class TestService {
  printMessage() {
    return "I'm printting this message inside of TestService instance.";
  }
}

@Singleton([TestService])
class Test {
  constructor(public testService: TestService) {}
}

const testInstance = container.resolve(Test);
console.log(testInstance.testService.printMessage());
// logs "I'm printting this message inside of TestService instance."

Available Decorators

• @Singleton
• @Transient
• @Scoped
• @AutoInjectable
• @Inject
• @InjectAll

Static Injection (without decorators)

STATIC_INJECTION_LIFETIME and STATIC_INJECTIONS

import {
  container,
  STATIC_INJECTIONS,
  STATIC_INJECTION_LIFETIME,
  StaticInjectable,
} from "@dymexjs/di";

class TestClass implements StaticInjectable<typeof TestClass> {
  public propertyA = "test";
  public static [STATIC_INJECTION_LIFETIME] = Lifetime.Singleton;
}
class TestClass2 implements StaticInjectable<typeof TestClass2> {
  constructor(public test: TestClass) {}
  public static [STATIC_INJECTIONS] = ["test"];
}
container.register("test", { useClass: TestClass });
const test2 = container.resolve(TestClass2);
console.log(test2.test.propertyA);
// logs "test"

This snippet creates (resolves to) one instance of TestClass that will be a Singleton instance and a Transient instance of TestClass2 that will have TestClass injected into the constructor.

Instead of using container.register it's also possible to use the TestClass directly:

import {
  container,
  STATIC_INJECTIONS,
  STATIC_INJECTION_LIFETIME,
  StaticInjectable,
} from "@dymexjs/di";

class TestClass implements StaticInjectable<typeof TestClass> {
  public propertyA = "test";
  public static [STATIC_INJECTION_LIFETIME] = Lifetime.Singleton;
}
class TestClass2 implements StaticInjectable<typeof TestClass2> {
  constructor(public test: TestClass) {}
  public static [STATIC_INJECTIONS] = [TestClass];
}
const test2 = container.resolve(TestClass2);
console.log(test2.test.propertyA);
// logs "test"

Use static [STATIC_INJECTION_LIFETIME] to define the lifetime of the instance created.

Use static [STATIC_INJECTIONS] to define the instances to inject into the constructor.

Lifetime

Lifetime defines how instances will be resolved (Lifetime = Scopes)

enum Lifetime {
  Singleton,
  Transient,
  Scoped,
}

• Singleton
  • Each resolve will return the same instance ( including resolves from child containers)
• Transient
  • This is the default registration scope, a new instance will be created with each resolve
• Scoped
  • The container will resolve always to the same instance, like the singleton, but only when inside a Scope, createScope for more info, when a scope is not defined the resolution will throw an Error.

Register

For using the resolving capabilities of the container first the things have to be registered, to achieve this, there are multiple ways, one of them is by usin register()

Resolution

Process to resolve a token into an instance, resolving all the necessary dependencies in between using resolve()

Child Containers and Scopes

It's possible to create child containers and scopes for the resolution of the token's, mode info here

Cleaning

It's also possible to clean the instances of one container or reset the container.

Circular Dependencies

Cyclic dependencies are a problem, and should be avoided, but sometimes that's not possible, to solve this problem the container resolves an already existing instance in resolution by creating a proxy of the instance that will later be resolved into the instance.

Documentation

The detailed usage guide and API documentation for the project can be found in the ./docs folder of the repository

Code of Conduct

We expect everyone to abide by our Code of Conduct. Please read it.

How to Contribute

Check out our Contributing Guide for information on contributing.

License 📝

Licensed under the MIT License

Contributors ✨

This project follows the all-contributors specification. Contributions of any kind welcome!