@swindle/cqrs

A Command Query Responsibility Segregation (CQRS) module for NodeJS

Installation

To install @Swindle/CQRS, use the following command with npm

npm install @swindle/cqrs

With Yarn,

yarn add @swindle/cqrs

Usage

Defining a Command

To define a Command, we extend the Command class.

import { Command } from '@swindle/cqrs`;

export class CreateUserCommand extends Command {

    constructor() {
        super();
    }

    public async execute(data: UserData): Promise<void> {
        // definition here.
    }
}

All commands extends the Command class. Every Command class defines an execute() method, wheich defines the body of the command. The execute() method is very flexible and allows you to pass in however many parameters you need.

We can use our command as follows.

import { CreateUserCommand } from './command.class';
import { UserData } from 'path/to/user/data';

const data: UserData = {
    id: 'some-id',
    name: 'John'
}

const createUser = new CreateUserCommand();
await createUser.execute(data);

Defining a Query

To define a query, we extend the Query class.

import { Query } from '@swindle/cqrs`;

export class GetUserByIdQuery extends Query {

    constructor() {
        super();
    }

    public async execute(id: string): Promise<UserData> {
        // definition here...
        return data;
    }
}

All queries extend the Query class. Every Query class defines an execute() method, wheich defines the body of the command. The execute() method is very flexible and allows you to pass in however many parameters you need.

We can use our query as follows.

import { GetUserByIdQuery } from './query.class';

const getUserById = new GetUserByIdQuery();
const user = await getUserById.execute('foo');
console.log(user);