alexandrereyes/nestjs-mediator

Motivation

NestJS has a lightweight CQRS module that works very well but the problem is we can not inject the other provider with scope-request and that is the reason why this package has existed

Description

The nestjs-mediator supports request/response, command, query, and notification with exposing the ability to inject any scope-request provider

Installation

$ npm install --save nestjs-mediator

or with yarn

$ yarn add nestjs-mediator

Quick Start(or reference in github example)

Request/Response

Define your query or command

import { Request } from "nestjs-mediator"

export class TestCommand extends Request<string>{
	//Your properties
}

Then define your handler

import { RequestHandler, IRequestHandler } from "nestjs-mediator"

@RequestHandler(TestCommand)
export class TestCommandHandler implements IRequestHandler<TestCommand, string> {
	handle(data: TestCommand): Promise<string>{
		//Your logic
	}
}

Don't forget to import your CommandHandler and MediatorModule into your module

import { MediatorModule } from "nestjs-mediator"

@Module({
	imports: [MediatorModule],
	providers: [TestCommandHandler]
})

class TestModule{}

Finally, send your command through the mediator:

import { Mediator } from "nestjs-mediator"

@Controller()
export class TestController {
	constructor(private mediator: Mediator){}

	@Post()
	post(){
		return this.mediator.send(new TestCommand());
	}
}

Notification

Define your notification

import { Notification } from "nestjs-mediator"

export class TestNotification extends Notification{
	//Your properties
}

and then define many handlers that you want to receive this notification

import { NotificationHandler, INotificationHandler } from "nestjs-mediator"

@NotificationHandler(TestNotification)
export class TestNotificationHandler1 implements INotificationHandler<TestNotification>{
	handle(data: TestNotification){
		//Your logic
	}
}

@NotificationHandler(TestNotification)
export class TestNotificationHandler2 implements INotificationHandler<TestNotification>{
	handle(data: TestNotification){
		//Your logic
	}
}

Import MediatorModule and your handler the same as above and finally, publish your message via the mediator

import { Mediator } from "nestjs-mediator"

@Controller()
export class TestController {
	constructor(private mediator: Mediator){}

	@Post()
	post(){
		this.mediator.publish(new TestNotification())
	}
}

Types

Request<T> - where T is the returns value

RequestHandler<T> - the decorator where T is your request

IRequestHandler<T, U> - you must implement this interface, T is your request and U is your return value

Notification

NotificationHandler<T> - the decorator where T is your notification

INotificationHandler<T> - the interface that you have to implement to publish your notification