Answer:1 Projection

apps/angular/1-projection/src/app/component/city-card/city-card.component.ts

@@ -1,9 +1,67 @@
-import { ChangeDetectionStrategy, Component } from '@angular/core';
+import { NgOptimizedImage } from '@angular/common';
+import {
+  ChangeDetectionStrategy,
+  Component,
+  effect,
+  inject,
+} from '@angular/core';
+import { toSignal } from '@angular/core/rxjs-interop';
+import { CityStore } from '../../data-access/city.store';
+import {
+  FakeHttpService,
+  randomCity,
+} from '../../data-access/fake-http.service';
+import { CardItemDirective } from '../../directive/card-item.directive';
+import { CardComponent } from '../../ui/card/card.component';
+import { ListItemComponent } from '../../ui/list-item/list-item.component';
 
 @Component({
   selector: 'app-city-card',
-  template: 'TODO City',
-  imports: [],
+  template: `
+    <app-card
+      [list]="cities()"
+      (add)="addCity()"
+      [style.--bg]="'rgba(250, 150, 0, 0.1)'">
+      <ng-template appCardItem let-item>
+        <app-list-item
+          [id]="item.id"
+          [name]="item.name"
+          (delete)="deleteCity($event)" />
+      </ng-template>
+      <ng-container card-image>
+        <img ngSrc="assets/img/city.png" width="200" height="200" alt="" />
+      </ng-container>
+    </app-card>
+  `,
+  imports: [
+    CardComponent,
+    ListItemComponent,
+    CardItemDirective,
+    NgOptimizedImage,
+  ],
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class CityCardComponent {}
+export class CityCardComponent {
+  private http = inject(FakeHttpService);
+  private store = inject(CityStore);
+
+  private fetchedCities = toSignal(this.http.fetchCities$);
+  cities = this.store.cities;
+
+  constructor() {
+    effect(() => {
+      const cities = this.fetchedCities();
+      if (cities) {
+        this.store.addAll(cities);
+      }
+    });
+  }
+
+  addCity(): void {
+    this.store.addOne(randomCity());
+  }
+
+  deleteCity(id: number): void {
+    this.store.deleteOne(id);
+  }
+}

apps/angular/1-projection/src/app/component/student-card/student-card.component.ts

@@ -1,40 +1,67 @@
+import { NgOptimizedImage } from '@angular/common';
 import {
   ChangeDetectionStrategy,
   Component,
+  effect,
   inject,
-  OnInit,
 } from '@angular/core';
-import { FakeHttpService } from '../../data-access/fake-http.service';
+import { toSignal } from '@angular/core/rxjs-interop';
+import {
+  FakeHttpService,
+  randStudent,
+} from '../../data-access/fake-http.service';
 import { StudentStore } from '../../data-access/student.store';
-import { CardType } from '../../model/card.model';
+import { CardItemDirective } from '../../directive/card-item.directive';
 import { CardComponent } from '../../ui/card/card.component';
+import { ListItemComponent } from '../../ui/list-item/list-item.component';
 
 @Component({
   selector: 'app-student-card',
   template: `
     <app-card
       [list]="students()"
-      [type]="cardType"
-      customClass="bg-light-green" />
+      (add)="addStudent()"
+      [style.--bg]="'rgba(0, 250, 0, 0.1)'">
+      <ng-template appCardItem let-item>
+        <app-list-item
+          [id]="item.id"
+          [name]="item.firstName"
+          (delete)="deleteStudent($event)" />
+      </ng-template>
+      <ng-container card-image>
+        <img ngSrc="assets/img/student.webp" width="200" height="200" alt="" />
+      </ng-container>
+    </app-card>
   `,
-  styles: [
-    `
-      ::ng-deep .bg-light-green {
-        background-color: rgba(0, 250, 0, 0.1);
-      }
-    `,
+  imports: [
+    CardComponent,
+    ListItemComponent,
+    CardItemDirective,
+    NgOptimizedImage,
   ],
-  imports: [CardComponent],
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class StudentCardComponent implements OnInit {
+export class StudentCardComponent {
   private http = inject(FakeHttpService);
   private store = inject(StudentStore);
 
+  private fetchedStudents = toSignal(this.http.fetchStudents$);
   students = this.store.students;
-  cardType = CardType.STUDENT;
 
-  ngOnInit(): void {
-    this.http.fetchStudents$.subscribe((s) => this.store.addAll(s));
+  constructor() {
+    effect(() => {
+      const students = this.fetchedStudents();
+      if (students) {
+        this.store.addAll(students);
+      }
+    });
+  }
+
+  addStudent(): void {
+    this.store.addOne(randStudent());
+  }
+
+  deleteStudent(id: number): void {
+    this.store.deleteOne(id);
   }
 }

apps/angular/1-projection/src/app/component/teacher-card/teacher-card.component.ts

@@ -1,40 +1,66 @@
+import { NgOptimizedImage } from '@angular/common';
 import {
   ChangeDetectionStrategy,
   Component,
+  effect,
   inject,
-  OnInit,
 } from '@angular/core';
-import { FakeHttpService } from '../../data-access/fake-http.service';
+import { toSignal } from '@angular/core/rxjs-interop';
+import {
+  FakeHttpService,
+  randTeacher,
+} from '../../data-access/fake-http.service';
 import { TeacherStore } from '../../data-access/teacher.store';
-import { CardType } from '../../model/card.model';
+import { CardItemDirective } from '../../directive/card-item.directive';
 import { CardComponent } from '../../ui/card/card.component';
-
+import { ListItemComponent } from '../../ui/list-item/list-item.component';
 @Component({
   selector: 'app-teacher-card',
   template: `
     <app-card
       [list]="teachers()"
-      [type]="cardType"
-      customClass="bg-light-red"></app-card>
+      (add)="addTeacher()"
+      [style.--bg]="'rgba(250, 0, 0, 0.1)'">
+      <ng-template appCardItem let-item>
+        <app-list-item
+          [id]="item.id"
+          [name]="item.firstName"
+          (delete)="deleteTeacher($event)" />
+      </ng-template>
+      <ng-container card-image>
+        <img ngSrc="assets/img/teacher.png" width="200" height="200" alt="" />
+      </ng-container>
+    </app-card>
   `,
-  styles: [
-    `
-      ::ng-deep .bg-light-red {
-        background-color: rgba(250, 0, 0, 0.1);
-      }
-    `,
-  ],
   changeDetection: ChangeDetectionStrategy.Eager,
-  imports: [CardComponent],
+  imports: [
+    CardComponent,
+    ListItemComponent,
+    CardItemDirective,
+    NgOptimizedImage,
+  ],
 })
-export class TeacherCardComponent implements OnInit {
+export class TeacherCardComponent {
   private http = inject(FakeHttpService);
   private store = inject(TeacherStore);
 
+  private fetchedTeachers = toSignal(this.http.fetchTeachers$);
   teachers = this.store.teachers;
-  cardType = CardType.TEACHER;
 
-  ngOnInit(): void {
-    this.http.fetchTeachers$.subscribe((t) => this.store.addAll(t));
+  constructor() {
+    effect(() => {
+      const teachers = this.fetchedTeachers();
+      if (teachers) {
+        this.store.addAll(teachers);
+      }
+    });
+  }
+
+  addTeacher(): void {
+    this.store.addOne(randTeacher());
+  }
+
+  deleteTeacher(id: number): void {
+    this.store.deleteOne(id);
   }
 }

apps/angular/1-projection/src/app/data-access/city.store.ts

@@ -1,14 +1,18 @@
-import { Injectable, signal } from '@angular/core';
+import { Injectable, signal, untracked } from '@angular/core';
 import { City } from '../model/city.model';
 
 @Injectable({
   providedIn: 'root',
 })
 export class CityStore {
-  private cities = signal<City[]>([]);
+  public cities = signal<City[]>([]);
 
   addAll(cities: City[]) {
-    this.cities.set(cities);
+    const existingIds = new Set(untracked(this.cities).map((c) => c.id));
+    this.cities.set([
+      ...untracked(this.cities),
+      ...cities.filter((c) => !existingIds.has(c.id)),
+    ]);
   }
 
   addOne(city: City) {

apps/angular/1-projection/src/app/data-access/student.store.ts

@@ -1,4 +1,4 @@
-import { Injectable, signal } from '@angular/core';
+import { Injectable, signal, untracked } from '@angular/core';
 import { Student } from '../model/student.model';
 
 @Injectable({
@@ -8,7 +8,11 @@ export class StudentStore {
   public students = signal<Student[]>([]);
 
   addAll(students: Student[]) {
-    this.students.set(students);
+    const existingIds = new Set(untracked(this.students).map((s) => s.id));
+    this.students.set([
+      ...untracked(this.students),
+      ...students.filter((s) => !existingIds.has(s.id)),
+    ]);
   }
 
   addOne(student: Student) {

apps/angular/1-projection/src/app/data-access/teacher.store.ts

@@ -1,4 +1,4 @@
-import { Injectable, signal } from '@angular/core';
+import { Injectable, signal, untracked } from '@angular/core';
 import { Teacher } from '../model/teacher.model';
 
 @Injectable({
@@ -8,7 +8,11 @@ export class TeacherStore {
   public teachers = signal<Teacher[]>([]);
 
   addAll(teachers: Teacher[]) {
-    this.teachers.set(teachers);
+    const existingIds = new Set(untracked(this.teachers).map((t) => t.id));
+    this.teachers.set([
+      ...untracked(this.teachers),
+      ...teachers.filter((t) => !existingIds.has(t.id)),
+    ]);
   }
 
   addOne(teacher: Teacher) {

apps/angular/1-projection/src/app/directive/card-item.directive.ts

@@ -0,0 +1,8 @@
+import { Directive, inject, TemplateRef } from '@angular/core';
+
+@Directive({
+  selector: '[appCardItem]',
+})
+export class CardItemDirective {
+  templateRef = inject(TemplateRef);
+}

apps/angular/1-projection/src/app/ui/card/card.component.ts

@@ -1,64 +1,46 @@
-import { NgOptimizedImage } from '@angular/common';
+import { CommonModule } from '@angular/common';
 import {
   ChangeDetectionStrategy,
   Component,
-  inject,
+  contentChild,
   input,
+  output,
 } from '@angular/core';
-import { randStudent, randTeacher } from '../../data-access/fake-http.service';
-import { StudentStore } from '../../data-access/student.store';
-import { TeacherStore } from '../../data-access/teacher.store';
-import { CardType } from '../../model/card.model';
-import { ListItemComponent } from '../list-item/list-item.component';
+import { CardItemDirective } from '../../directive/card-item.directive';
 
 @Component({
   selector: 'app-card',
   template: `
     <div
-      class="flex w-fit flex-col gap-3 rounded-md border-2 border-black p-4"
-      [class]="customClass()">
-      @if (type() === CardType.TEACHER) {
-        <img ngSrc="assets/img/teacher.png" width="200" height="200" alt="" />
-      }
-      @if (type() === CardType.STUDENT) {
-        <img ngSrc="assets/img/student.webp" width="200" height="200" alt="" />
-      }
-
+      class="card-container flex w-fit flex-col gap-3 rounded-md border-2 border-black p-4">
+      <ng-content select="[card-image]"></ng-content>
       <section>
         @for (item of list(); track item) {
-          <app-list-item
-            [name]="item.firstName"
-            [id]="item.id"
-            [type]="type()"></app-list-item>
+          <ng-container
+            [ngTemplateOutlet]="itemTemplate().templateRef"
+            [ngTemplateOutletContext]="{ $implicit: item }"></ng-container>
         }
       </section>
 
       <button
         class="rounded-sm border border-blue-500 bg-blue-300 p-2"
-        (click)="addNewItem()">
+        (click)="add.emit()">
         Add
       </button>
     </div>
   `,
+  styles: [
+    `
+      .card-container {
+        background: var(--bg, gray);
+      }
+    `,
+  ],
   changeDetection: ChangeDetectionStrategy.Eager,
-  imports: [ListItemComponent, NgOptimizedImage],
+  imports: [CommonModule],
 })
 export class CardComponent {
-  private teacherStore = inject(TeacherStore);
-  private studentStore = inject(StudentStore);
-
   readonly list = input<any[] | null>(null);
-  readonly type = input.required<CardType>();
-  readonly customClass = input('');
-
-  CardType = CardType;
-
-  addNewItem() {
-    const type = this.type();
-    if (type === CardType.TEACHER) {
-      this.teacherStore.addOne(randTeacher());
-    } else if (type === CardType.STUDENT) {
-      this.studentStore.addOne(randStudent());
-    }
-  }
+  readonly itemTemplate = contentChild.required(CardItemDirective);
+  add = output<void>();
 }