Nest.js CQRS Proxy Bus

The package provides a CQRS Proxy Bus for Nest.js applications. It allows you to create a proxy bus that can be used to send commands to different handlers by @nestjs/microservices workflow and handle them by workers.

Useful Links

• Nest.js Microservices
• Nest.js CQRS

Installation

You can install it using yarn or any other package manager:

yarn add cqrs-proxy

Don't forget to setup peer dependencies:

yarn add @nestjs/cqrs @nestjs/schematics @nestjs/common @nestjs/core @nestjs/microservices rxjs uuid class-transformer

Usage

Importing the Module

To use the CQRS Proxy Bus, you need to import the CqrsProxyClientModule into your Nest.js module as client:

import { CqrsProxyClientModule } from 'cqrs-proxy'

@Module({
  imports: [
    CqrsProxyClientModule.register({
      clientToken: 'AMQP_CLIENT', // The name of the microservice
      useSyncMode: false, // Set to true if you want to use synchronous mode for DEBUG
    }),
  ],
})
export class MyModule {}

Async mode

You can also use the async mode to register the module:

import { CqrsProxyClientModule } from 'cqrs-proxy'

@Module({
  imports: [
    CqrsProxyClientModule.registerAsync({
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: (config: ConfigService) => ({
        clientToken: config.get('clientToken', 'AMQP_CLIENT'),
        useSyncMode: config.get('useWorker', true),
      }),
    }),
  ],
})
export class MyModule {}

Sending Commands

You can send commands using the ProxyBus service. Here's an example of how to send a command:

import { Injectable } from '@nestjs/common'
import { ICommand } from '@nestjs/cqrs'

import { ProxyBus } from 'cqrs-proxy'

class MyCommand implements ICommand {
  constructor(public readonly data: string) {}
}

@Injectable()
export class MyService {
  constructor(private readonly proxyBus: ProxyBus) {}

  public async run(): Promise<void> {
    const command = new MyCommand('Hello, World!')
    await this.proxyBus.execute(command) // returns metadata with id
  }
}

Handling Commands

All magic happens in the worker. You need to import CqrsProxyWorkerModule into your root module and create a handler for your command and register it in the worker module using default CqrsModule and command handler matching to MyCommand from example above:

import { Module } from '@nestjs/common'
import { CqrsModule } from '@nestjs/cqrs'
import { CqrsProxyWorkerModule } from 'cqrs-proxy'

import { MyCommandHandler } from './my-command.handler'
import { MyCommand } from './my-command.command'
import { MyService } from './my.service'

@CommandHandler(MyCommand)
export class MyCommandHandler implements ICommandHandler<MyCommand> {
  public async execute(command: MyCommand): Promise<void> {
    console.log('Handling command:', command.data) // Handling command: Hello, World!
  }
}

@Module({
  imports: [CqrsModule, CqrsProxyWorkerModule.forRoot()],
  providers: [MyService, MyCommandHandler],
})
export class MyWorkerModule {}

Contributing

I welcome contributions! Follow these steps to contribute:

1. Setup environment
   1. Fork the repository.
   2. Clone your forked repository.
   3. Install dependencies by running yarn install.
2. Making Changes
   1. Create a new branch for your changes.
   2. Make your changes and commit them.
   3. Push your changes to your forked repository.
3. Submitting a Pull Request
   1. Go to the original repository on GitHub and click the "New pull request" button.
   2. Select your branch and submit the pull request.
   3. Wait for the review and address any feedback.

You are the star of this project! 🌟