ngrx/data entity data service

Question

Trying to understand the ngrx/data entity data service example here, where it says "Creating entity data services". After showing that service, the docs go on to show how to use ngrx/data in components. The part of the component I'm interested in is this:

getHeroes() {
  this.heroService.getAll();
}

The docs state that getAll() initiates an HTTP request, but I'm not sure where or how this request is actually made. In the ngrx-data repo. It states to replace the heroService with the following code:

import { Injectable } from '@angular/core';
import {
  EntityCollectionServiceBase,
  EntityCollectionServiceElementsFactory
} from 'ngrx-data';
import { Hero } from '../core';

@Injectable({ providedIn: 'root' })
export class HeroService extends EntityCollectionServiceBase<Hero> {
  constructor(serviceElementsFactory: EntityCollectionServiceElementsFactory) {
    super('Hero', serviceElementsFactory);
  }
}

The docs state ngrx-data handles getting and saving our data for us. That's great, but I don't know where this getting data is happening. I cloned the repo, checked out the finish branch and could not find something that is hitting endpoints.

E.g. the service used to call http.get(${api}/heroes) for getAll() to get all the heroes, but that's replaced by the above code, so where are these calls occurring?

I notice that the EntityCollectionServiceBase has a getAll() method. But where is the configuration of this service taking place to register the respective endpoints? I'm sure that I am missing something incredibly simple here.

Answer 1

Broadly speaking the EntityCollectionServiceBase dispatches actions and via the persist effect in EntityEffects the DefaultDataService is called and maps the response to its success / fail actions. See Architecture Overview

Hence if you want to access / transform the data returned from the API you extend / replace the DefaultDataService. You can register your custom data service using EntityDataService which is basically a registry of data services that gets or creates the data service (uses default if none exists).