Typescript lightweight dependency injection container for express
Installation
yarn add @msiviero/knit-di-express
Example of usage
Base usage:
import * as express from "express";
import {
ApiContainer,
api,
component,
Container,
Exchange,
get
} from "@msiviero/knit-di-express";
const app = express();
const apiContainer = ApiContainer.getInstance();
@component()
class Greeter {
public greet(who: string) {
return `Hello ${who}`;
}
}
@api("/api/v1")
class ApiController {
constructor(private readonly greeter: Greeter) { }
@get("/hello")
public hello(exchange: Exchange) {
const who: string = exchange.request.query.who || "Nobody";
exchange.response.json({
message: this.greeter.greet(who),
});
}
}
apiContainer.registerApi(app, ApiController);
app.listen(3000);Mocking dependencies
Registering mock dependencies for unit tests can be easily achieved via:
const app = express();
const apiContainer = ApiContainer.withContainer(Container.newContainer());
@component()
class Greeter {
public greet(who: string) {
return `Hello ${who}`;
}
}
class CustomGreeter extends Greeter {
public greet(who: string) {
return `Custom Hello ${who}`;
}
}
apiContainer.container.provide(Greeter, () => new CustomGreeter());
@api("/api/v1")
class ApiController {
constructor(private readonly greeter: Greeter) { }
@get("/hello")
public hello(exchange: Exchange) {
const who: string = exchange.request.query.who || "Nobody";
exchange.response.json({
message: this.greeter.greet(who),
});
}
}
apiContainer.registerApi(app, ApiController);