[NgRx] Sort Entity with ngrx

Reducer:

import { Course, compareCourses } from "../model/course";
import { EntityState, createEntityAdapter } from "@ngrx/entity";
import { createReducer, on } from "@ngrx/store";
import { CoursesAction } from "../actions-types";

export interface CoursesState extends EntityState<Course> {
  /**Extend the entity here */
  allCoursesLoaded: boolean;
}

export const adapter = createEntityAdapter<Course>({
  sortComparer: compareCourses
  // selectId: course => course.id // NgRx use 'id' by default
});

export const initCoursesState = adapter.getInitialState({
  allCoursesLoaded: false
});

export const { selectAll } = adapter.getSelectors();

export const coursesReducer = createReducer(
  initCoursesState,
  on(CoursesAction.allCoursesLoaded, (state, action) =>
    adapter.addAll(action.courses, { ...state, allCoursesLoaded: true })
  ),

  on(CoursesAction.courseUpdated, (state, action) =>
    adapter.updateOne(action.update, state)
  )
);

Sort compare:

export interface Course {
  id: number;
  seqNo:number;
  url:string;
  iconUrl: string;
  courseListIcon: string;
  description: string;
  longDescription?: string;
  category: string;
  lessonsCount: number;
  promo: boolean;
}


export function compareCourses(c1:Course, c2: Course) {

  const compare = c1.seqNo - c2.seqNo;

  if (compare > 0) {
    return 1;
  }
  else if ( compare < 0) {
    return -1;
  }
  else return 0;

}

Selector:

import { createSelector, createFeatureSelector } from "@ngrx/store";
import * as fromCourses from "./reducers/courses.reducers";

export const selectCoursesState = createFeatureSelector<
  fromCourses.CoursesState
>("courses");

export const selectAllCourses = createSelector(
  selectCoursesState,
  fromCourses.selectAll
);

export const selectAllCoursesLoaded = createSelector(
  selectCoursesState,
  state => state.allCoursesLoaded
);

export const selectBeginnerCourses = createSelector(
  selectAllCourses,
  courses => courses.filter(course => course.category === "BEGINNER")
);

export const selectAdvancedCourses = createSelector(
  selectAllCourses,
  courses => courses.filter(course => course.category === "ADVANCED")
);

export const selectPromoTotal = createSelector(
  selectAllCourses,
  courses => courses.filter(course => course.promo).length
);

Resolver:

import { Injectable } from "@angular/core";
import {
  Resolve,
  ActivatedRouteSnapshot,
  RouterStateSnapshot
} from "@angular/router";
import { Observable } from "rxjs";
import { Store, select } from "@ngrx/store";
import { AppState } from "../reducers";
import { CoursesAction } from "./actions-types";
import { tap, first, finalize, filter } from "rxjs/operators";
import { adapter } from "./reducers/courses.reducers";
import { selectAllCoursesLoaded } from "./courses.selectors";

@Injectable()
export class CoursesResolver implements Resolve<any> {
  loading = false;
  constructor(private store: Store<AppState>) {}

  resolve(
    route: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ): Observable<any> {
    return this.store.pipe(
      select(selectAllCoursesLoaded),
      tap(courseLoaded => {
        if (!this.loading && !courseLoaded) {
          this.loading = true;
          this.store.dispatch(CoursesAction.loadAllCourse());
        }
      }),
      // this resolve need to complete, so we can use first()
      first(loaded => loaded),
      finalize(() => (this.loading = false))
    );
  }
}