Answer:1 - Refactor CardComponent with content projection and directive

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

@@ -1,3 +1,4 @@
+// app.component.ts
 import { ChangeDetectionStrategy, Component } from '@angular/core';
 import { CityCardComponent } from './component/city-card/city-card.component';
 import { StudentCardComponent } from './component/student-card/student-card.component';

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

@@ -1,9 +1,60 @@
-import { ChangeDetectionStrategy, Component } from '@angular/core';
+// city-card.component.ts
+import {
+  ChangeDetectionStrategy,
+  Component,
+  inject,
+  OnInit,
+} from '@angular/core';
+import { CityStore } from '../../data-access/city.store';
+import {
+  FakeHttpService,
+  randomCity,
+} from '../../data-access/fake-http.service';
+import { CardRowDirective } from '../../ui/card/card-row.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: [],
+  standalone: true,
+  imports: [CardComponent, ListItemComponent, CardRowDirective],
+  template: `
+    <app-card [list]="cities()" customClass="bg-yellow-500/10">
+      <!-- 1. Projected City Image -->
+      <img src="assets/img/city.png" width="200" height="200" alt="city" />
+
+      <!-- 2. Projected Row Template for City Name -->
+      <ng-template cardRow let-city>
+        <app-list-item (deleted)="deleteCity(city.id)">
+          {{ city.name }}
+        </app-list-item>
+      </ng-template>
+
+      <!-- 3. Projected Add Button -->
+      <button
+        class="rounded-sm border border-blue-500 bg-blue-300 p-2"
+        (click)="addCity()">
+        Add
+      </button>
+    </app-card>
+  `,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class CityCardComponent {}
+export class CityCardComponent implements OnInit {
+  private http = inject(FakeHttpService);
+  private store = inject(CityStore);
+
+  readonly cities = this.store.cities;
+
+  ngOnInit(): void {
+    this.http.fetchCities$.subscribe((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

@@ -1,21 +1,46 @@
+// student-card.component.ts
 import {
   ChangeDetectionStrategy,
   Component,
   inject,
   OnInit,
 } from '@angular/core';
-import { FakeHttpService } from '../../data-access/fake-http.service';
+import {
+  FakeHttpService,
+  randStudent,
+} from '../../data-access/fake-http.service'; // Fix 2: Imported randStudent
 import { StudentStore } from '../../data-access/student.store';
-import { CardType } from '../../model/card.model';
+import { CardRowDirective } from '../../ui/card/card-row.directive'; // Added missing import
 import { CardComponent } from '../../ui/card/card.component';
+import { ListItemComponent } from '../../ui/list-item/list-item.component'; // Added missing import
 
 @Component({
   selector: 'app-student-card',
   template: `
-    <app-card
-      [list]="students()"
-      [type]="cardType"
-      customClass="bg-light-green" />
+    <app-card [list]="students()" customClass="bg-light-green">
+      <!-- Fix 1: Removed the trailing '/' so it is no longer self-closing -->
+
+      <!-- 1. Project image -->
+      <img
+        src="assets/img/student.webp"
+        width="200"
+        height="200"
+        alt="student" />
+
+      <!-- 2. Project list item template -->
+      <ng-template cardRow let-student>
+        <app-list-item (deleted)="deleteStudent(student.id)">
+          {{ student.firstName }}
+        </app-list-item>
+      </ng-template>
+
+      <!-- 3. Project Add button -->
+      <button
+        class="rounded-sm border border-blue-500 bg-blue-300 p-2"
+        (click)="addStudent()">
+        Add
+      </button>
+    </app-card>
   `,
   styles: [
     `
@@ -24,17 +49,24 @@ import { CardComponent } from '../../ui/card/card.component';
       }
     `,
   ],
-  imports: [CardComponent],
+  imports: [CardComponent, ListItemComponent, CardRowDirective], // Added missing components/directives to imports
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class StudentCardComponent implements OnInit {
   private http = inject(FakeHttpService);
   private store = inject(StudentStore);
 
-  students = this.store.students;
-  cardType = CardType.STUDENT;
+  readonly students = this.store.students;
 
   ngOnInit(): void {
     this.http.fetchStudents$.subscribe((s) => this.store.addAll(s));
   }
+
+  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 @@
+// teacher-card.component.ts
 import {
   ChangeDetectionStrategy,
   Component,
   inject,
   OnInit,
 } from '@angular/core';
-import { FakeHttpService } from '../../data-access/fake-http.service';
+import {
+  FakeHttpService,
+  randTeacher,
+} from '../../data-access/fake-http.service';
 import { TeacherStore } from '../../data-access/teacher.store';
-import { CardType } from '../../model/card.model';
+import { CardRowDirective } from '../../ui/card/card-row.directive';
 import { CardComponent } from '../../ui/card/card.component';
-
+import { ListItemComponent } from '../../ui/list-item/list-item.component';
 @Component({
   selector: 'app-teacher-card',
+  standalone: true,
+  imports: [CardComponent, ListItemComponent, CardRowDirective],
   template: `
-    <app-card
-      [list]="teachers()"
-      [type]="cardType"
-      customClass="bg-light-red"></app-card>
+    <app-card [list]="teachers()" customClass="bg-red-500/10">
+      <!-- 1. Projected Image -->
+      <img
+        src="assets/img/teacher.png"
+        width="200"
+        height="200"
+        alt="teacher" />
+
+      <!-- 2. Row Template passed via CardRowDirective -->
+      <ng-template cardRow let-teacher>
+        <app-list-item (deleted)="deleteTeacher(teacher.id)">
+          {{ teacher.firstName }}
+        </app-list-item>
+      </ng-template>
+
+      <!-- 3. Projected Add Button -->
+      <button
+        class="rounded-sm border border-blue-500 bg-blue-300 p-2"
+        (click)="addTeacher()">
+        Add
+      </button>
+    </app-card>
   `,
-  styles: [
-    `
-      ::ng-deep .bg-light-red {
-        background-color: rgba(250, 0, 0, 0.1);
-      }
-    `,
-  ],
   changeDetection: ChangeDetectionStrategy.Eager,
-  imports: [CardComponent],
 })
 export class TeacherCardComponent implements OnInit {
   private http = inject(FakeHttpService);
   private store = inject(TeacherStore);
 
-  teachers = this.store.teachers;
-  cardType = CardType.TEACHER;
+  // teachers = this.store.teachers;
+  // cardType = CardType.TEACHER;
+
+  readonly teachers = this.store.teachers;
 
   ngOnInit(): void {
     this.http.fetchTeachers$.subscribe((t) => this.store.addAll(t));
   }
+
+  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

@@ -1,21 +1,23 @@
+// city.store.ts
 import { Injectable, signal } from '@angular/core';
 import { City } from '../model/city.model';
 
 @Injectable({
   providedIn: 'root',
 })
 export class CityStore {
-  private cities = signal<City[]>([]);
+  readonly #cities = signal<City[]>([]);
+  readonly cities = this.#cities.asReadonly();
 
   addAll(cities: City[]) {
-    this.cities.set(cities);
+    this.#cities.set(cities);
   }
 
   addOne(city: City) {
-    this.cities.set([...this.cities(), city]);
+    this.#cities.set([...this.#cities(), city]);
   }
 
   deleteOne(id: number) {
-    this.cities.set(this.cities().filter((s) => s.id !== id));
+    this.#cities.set(this.#cities().filter((s) => s.id !== id));
   }
 }

apps/angular/1-projection/src/app/data-access/fake-http.service.ts

@@ -1,3 +1,4 @@
+// fake-http.service.ts
 import { Injectable } from '@angular/core';
 import {
   incrementalNumber,

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

@@ -0,0 +1,13 @@
+import { Directive, inject, TemplateRef } from '@angular/core';
+
+export interface CardRowContext<T> {
+  $implicit: T;
+}
+
+@Directive({
+  selector: 'ng-template[cardRow]',
+  standalone: true,
+})
+export class CardRowDirective<T> {
+  readonly templateRef = inject(TemplateRef<CardRowContext<T>>);
+}

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

@@ -1,64 +1,49 @@
-import { NgOptimizedImage } from '@angular/common';
+// card.component.ts
+
+import { NgTemplateOutlet } from '@angular/common';
 import {
   ChangeDetectionStrategy,
   Component,
-  inject,
+  contentChild,
   input,
 } 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 { 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 { CardRowDirective } from './card-row.directive';
 
 @Component({
   selector: 'app-card',
+  standalone: true,
+  imports: [NgTemplateOutlet],
   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="" />
-      }
+      <!-- 1. Multi-slot projection for image -->
+      <ng-content select="img" />
 
+      <!-- 2. @for loop remains here, rendering projected row template -->
       <section>
-        @for (item of list(); track item) {
-          <app-list-item
-            [name]="item.firstName"
-            [id]="item.id"
-            [type]="type()"></app-list-item>
+        @for (item of list(); track item.id) {
+          <ng-container
+            [ngTemplateOutlet]="rowTemplate()?.templateRef ?? null"
+            [ngTemplateOutletContext]="{ $implicit: item }" />
         }
       </section>
 
-      <button
-        class="rounded-sm border border-blue-500 bg-blue-300 p-2"
-        (click)="addNewItem()">
-        Add
-      </button>
+      <!-- 3. Multi-slot projection for add button -->
+      <ng-content select="button" />
     </div>
   `,
   changeDetection: ChangeDetectionStrategy.Eager,
-  imports: [ListItemComponent, NgOptimizedImage],
 })
-export class CardComponent {
-  private teacherStore = inject(TeacherStore);
-  private studentStore = inject(StudentStore);
-
-  readonly list = input<any[] | null>(null);
-  readonly type = input.required<CardType>();
+export class CardComponent<T extends { id: number }> {
+  readonly list = input<T[] | null>(null);
   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());
-    }
-  }
+  // Bonus: Query row template via Directive instead of magic string
+  readonly rowTemplate = contentChild(CardRowDirective<T>);
 }