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
    • Decorators
      • Available Decorators
    • Static Injection (without decorators)
    • Lifetime
    • Register
    • Resolution
    • Child Containers and Scopes
    • Cleaning
  • Circular Dependencies
  • Documentation
  • License

Instalation

npm install --save @dymexjs/di

Basic Usage

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

License

The MIT License (MIT)

Copyright (c) 2024 João Parreira

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.