@rezdy/dependency-injection

Rezdy Dependency Injection Container

Getting Started

import DIContainer, { object, get, factory, IDIContainer } from "@rezdy/dependency-injection";

const config = {
    "ENV": "PRODUCTION",               // define raw value
    "AuthStorage": object(AuthStorage).construct(
       get("Storage")                         // refer to another dependency       
    ),
    "Storage": object(CookieStorage),         // constructor without arguments       
    "BrowserHistory": factory(configureHistory), // factory (will be called only once)  
};
const container = new DIContainer();
container.addDefinitions(config);

function configureHistory(container: IDIContainer): History {
    const history = createBrowserHistory();
    const env = container.get("ENV");
    if (env === "production") {
        // do what you need
    }
    return history;
}

// in your code

const env = container.get<string>("ENV"); // PRODUCTION
const authStorage = container.get<AuthStorage>("AuthStorage");  // object of AuthStorage
const history = container.get<History>("BrowserHistory");  // History singleton will be returned

All definitions are resolved once and their result is kept during the life of the container.

Features

• Simple but powerful
• Does not requires decorators
• Works great with both javascript and typescript

Motivation

Popular solutions like inversify or tsyringe use reflect-metadata that allows to fetch argument types and based on those types and do autowiring. Autowiring is a nice feature but the trade-off is decorators. Disadvantages of other solutions

1. Those solutions work with typescript only. Since they rely on argument types that we don't have in Javascript.
2. I have to update my tsconfig because one package requires it.
3. Let my components know about injections.

@injectable()
class Foo {  
}

Why component Foo should know that it's injectable?

More details thoughts in my blog article

Raw values

import DIContainer from "@rezdy/dependency-injection";

const container = new DIContainer();
container.addDefinitions({   
    "ENV": "PRODUCTION",  
    "AuthStorage": new AuthStorage(),
    "BrowserHistory": createBrowserHistory(),
});
const env = container.get<string>("ENV"); // PRODUCTION    
const authStorage = container.get<AuthStorage>("AuthStorage"); // instance of AuthStorage     
const authStorage = container.get<History>("BrowserHistory"); // instance of AuthStorage     

When you specify raw values (i.e. don't use object, factory definitions) @rezdy/dependency-injection will resolve as it is.

Object definition

  
import DIContainer, { object, get } from "@rezdy/dependency-injection";
  
const container = new DIContainer();
container.addDefinitions({
   "Storage": object(CookieStorage),         // constructor without arguments
   "AuthStorage": object(AuthStorage).construct(
      get("Storage")                         // refers to existing dependency       
   ),  
   "UsersController": object(UserController),
   "PostsController": object(PostsController),
   "ControllerContainer": object(ControllerContainer)
     .method('addController', get("UsersController"))
     .method('addController', get("PostsController"))
});

object(ClassName) - the simplest scenario that will call new ClassName(). When you need to pass arguments to the constructor, you can use constructor method. You can refer to the existing definitions via get helper. If you need to call object method after initialization you can use method it will be called after constructor. You also can refer to the existing definitions via get method.

Factory definition

You can use factory definition when you need more flexibility during initialisation. container: IDIContainer will be pass as an argument to the factory method.

import DIContainer, {  factory, IDIContainer } from "@rezdy/dependency-injection";

const container = new DIContainer();
container.addDefinitions({       
  "BrowserHistory": factory(configureHistory),   
});

function configureHistory(container: IDIContainer): History {
    const history = createBrowserHistory();
    const env = container.get("ENV");
    if (env === "production") {
        // do what you need
    }
    return history;
}
const history = container.get<History>("BrowserHistory");