ember-data-cascade-delete

Sometimes we have a "Composition" kind of relationship (per UML terms) where the lifecyle of one class is closely related to another.

Composition relationships represents a "part-whole" relationship such that class B is an integral part of class A. This relationship is typically used if objects of class A can't logically exist without having a class B object.

E.g, if a Human model "has many" Legs, we want to destroy the legs if/when the Human is destroyed.

For such cases, we need to "cascade delete" the related models along with the parent model. This addon provides a Mixin with this functionality for you to add to any adapter in your ember app.

Installation

Just run

ember install ember-data-cascade-delete

Usage

If we want to add this feature globally, we add the Mixin to the application adapter:

// app/adapters/application.js
import JSONAPIAdapter from '@ember-data/adapter/json-api';
import CascadeDeleteMixin from 'ember-data-cascade-delete';

export default class ApplicationAdapter extends JSONAPIAdapter.extend(CascadeDeleteMixin) {
}

You can also add this mixin to any other more specific (model-scoped) adapter.

Now we can specify a cascadeDelete option in our relationships like:

// app/models/human.js
import Model, { attr, belongsTo, hasMany } from '@ember-data/model';

export default class Human extends Model {
  @attr('string')
  name;

  @belongsTo('heart', { async: true, inverse: 'human', cascadeDelete: true })
  heart;

  @hasMany('leg', { async: true, inverse: 'human', cascadeDelete: true })
  legs;
}

Now when we call human.destroyRecord() the related records marked with cascadeDelete: true will be unloaded after the main record is destroyed.

Two things to note:

• this will work with nested relationships, e.g a Leg could have a hasMany relationship to Finger and those would also be unloaded.
• beware of circular relationships. If you define cascadeDelete: true on both ends of a relationship, you will get infinite loops.

Credits

This addon is essentially the addonified version of this blog post, with the additional feature of nested cascade delete relationships.

Running

• ember serve
• Visit your app at http://localhost:4200.

Running Tests

• npm test (Runs ember try:each to test your addon against multiple Ember versions)
• ember test
• ember test --server

Building

• ember build

For more information on using ember-cli, visit https://ember-cli.com/.