npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

@cashfarm/plow

v0.5.0

Published

Library for validating input data and parameters

Downloads

123

Readme

Plow

Get the soil read to grow awesomeness :)

Documentation (Can't call it a proper doc, but here it goes)

The building blocks

Domain Events

Events represent change. Specifically a change that has already happened. They are immutable. Events are used inside Entities to apply the change to it's internal state and are propagated throughout the system to notify interested parties that something happened.

Here's is a simple event implementation that represents the fact that a task was completed:

import { Guid } from '@cashfarm/lang';
import { IDomainEvent } from '@cashfarm/plow';

@DomainEvent
class TaskCompleted {
    constructor(
        public readonly taskId: Guid,
        public readonly done: boolean
    ) {}
}

Entity and AggregateRoot<TId> classes

You model your domain using Entities and Aggregate Roots (AR). Only AR classes should be used to modify the system state. Aggregate Roots should protect their internal state, expose semantic methods and modify their internal state by applying events. Here's a simple example of what an AR should look like:

import { Guid, isEmpty } from '@cashfarm/lang';
import { AggregateRoot, Apply, IDomainEvent, Event } from '@cashfarm/plow';

import { TaskCompleted } from '../events';

class Task extends AggregateRoot<Guid> {
    private _description: string;
    public get description(): string {
        return this._description;
    }

    private _done: boolean;
    public get done(): boolean {
        return this._done;
    }

    constructor(desc: string) {
        if (isEmpty(desc)) {
            throw new DomainException('Task description cannot be empty');
        }

        this._desc = desc;
        this._done = false;
    }

    public complete() {
        this.applyChange(new TaskCompleted(true));
    }

    public [Apply(TaskCompleted)](evt: TaskCompleted) {
        this._done = evt.done;
    }
}

Repositories

Repositories are how we call the classes that permanently store aggregate roots. If you are using GetEventStore to store your aggregates, all you need to do is extend the class EventSourcedRepositoryOf<TAggregate, TAggtId>;

If you are using Plow's container, you can simply inject IEventStore and IEventBus as they are already configured in the inversify container.

export class TaskRepository extends EventSourcedRepositoryOf<Task, Guid> {
  constructor(
    @inject(IEventStore) protected storage: IEventStore,
    @inject(IEventBus) eventBus: IEventBus
  ) {
    super(storage, Campaign, eventBus);
  }
}

Projections

A projection class implements methods that handle events with the intent of projecting the data to a read model. The read model is a denormalized databsed optimized for reading.

Here's an example of a projection that sums up the number of completed tasks

import { Handle } from '@cashfarm/plow';

import { TaskCompleted } from '../events';

@Projection(TaskCompleted) // This decorator will register the projection in the event bus
export class TaskProjections {
  constructor(
      @inject(TaskStore) private tasks: TaskStore,
      @inject(UserStore) private users: UserStore) {}

  public [Handle(TaskCompleted)](event: TaskCompleted): void {
    debug('Running projection for TaskCompleted');
    const task = this.tasks.findById(event.taskId);
    const user = this.users.findById(task.userId);

    user.completedTasks += 1;

    this.users.update(user);
  }
}

Changelog

0.4

  • Plow now has an internal inversify container for dependency injection
  • Use @Projection, @Controller and @DomainEvent to register the respective classes
  • No need for [Symbol.EventLoader]() and [Symbol.MAPPER]() methods

Roadmap

Sometime

  • create a generator (yeoman or vscode) to generate boilerplates for:
    • Stores and Repositories
    • events
    • AggregateRoots
    • Endpoints
    • Projections