README

feathers-trigger

Documentation

For more information, please have a look at the docs: https://feathers-trigger.netlify.app/

Installation

npm i feathers-trigger

Usage

Imagine you want to notify users when a post gets published.

How can this be done? In this example a post has a publishedAt property which shows when a post was published. A post with publishedAt === null means that the post is not published yet. A post can be created as a draft which is not published.

But how do you know when a post gets published? Sounds silly, but there are three possibilities:

A post gets created with publishedAt: { $ne: null }.
A post gets updated by data publishedAt: { $ne: null }, it had publishedAt: null before and the result really has publishedAt: { $ne: null }.
A post gets patched by data publishedAt: { $ne: null }, it had publishedAt: null before and the result really has publishedAt: { $ne: null }.

How can this be accomplished?

Check context.data for publishedAt: { $ne: null } and if that's not true, the subscription is not true.
Check if the post in the database has publishedAt === null and therefore is not published yet. You need to check that in a before hook. If that's not true, the subscription is not true.
Check if the context.result really has publishedAt: { $ne: null } (maybe it's handled by another permission hook, or something). If that's not true, the subscription is not true.
If all three checks are true, run the notify function.

It's up to you how you define the notify action. For the example above the solution with feathers-trigger looks like the following:

// posts.hooks.js
import { trigger } from 'feathers-trigger';

const notifyPublished = trigger({
  conditionsData: { publishedAt: { $ne: null } },
  conditionsBefore: { publishedAt: null },
  conditionsResult: { publishedAt: { $ne: null }},
  action: ({ item }, context) => {
    return context.app.service('/notify').create(item);
  }
});

export default {
  before: {
    create: [ notifyPublished ],
    update: [ notifyPublished ],
    patch: [ notifyPublished ]
  },
  after: {
    create: [ notifyPublished ],
    update: [ notifyPublished ],
    patch: [ notifyPublished ]
  }
}

For more advanced examples, please have a look at the docs

Testing

Simply run npm test and all your tests in the test/ directory will be run. It has full support for Visual Studio Code. You can use the debugger to set breakpoints.

Help

For more information on all the things you can do, visit FeathersJS.

License

Licensed under the MIT license.

Usage no npm install needed!