IWA/project-front/src/app/students/students.component.ts

import { Component, OnInit } from '@angular/core';
import {Student} from "./student.model";
import {StudentService} from "./student.service";

@Component({
  selector: 'app-students',
  templateUrl: './students.component.html',
  styleUrls: ['./students.component.css']
})
export class StudentsComponent implements OnInit {
  studentList?: Student[];
  student?: Student;

  constructor(private studentService: StudentService) { }

  ngOnInit() { this.getStudents();   }

  getStudents(): void {
    this.studentService.getStudents()
      .subscribe(studentList => this.studentList = studentList);
  }

  add(firstname: string, lastname: string, email: string, telephone: string): void {
    firstname = firstname.trim();
    lastname = lastname.trim();
    email = email.trim();
    telephone = telephone.trim();
    this.studentService.addStudent({ firstname, lastname, email, telephone } as Student)
      .subscribe({
        next: (student: Student) => { this.studentList?.push(student); },
        error: () => {},
        complete: () => {
          if (this.studentList != undefined) {
            this.studentService.totalItems.next(this.studentList.length);
          }
        }
  });
  }

  delete(student: Student): void {
    this.studentList = this.studentList?.filter(c => c !== student);
    this.studentService.deleteStudent(student).subscribe(() => {
        // for automatic update of number of students in parent component
      if(this.studentList != undefined) {
        this.studentService.totalItems.next(this.studentList.length);
      }
      }
    );
  }

  deleteAll(): void {
    this.studentService.deleteStudents().subscribe(() => {
      }
    );
  }

}