13. Update Student Feature Backend

1. add update student link on students page

            <td>
                <a th:href="@{/students/{studentId}/edit(studentId=${student.id})}" class="btn btn-primary">Edit</a>
            </td>

2. Create handler method in StudentController

    // handler method to handle edit student request
    @GetMapping("students/{studentId}/edit")
    public String editStudent(@PathVariable("studentId") Long studentId,
                              Model model){
        StudentDto student = studentService.getStudentById(studentId);
        // add student object to model
        model.addAttribute("student", student);
        return "edit_student";
    }

3. Service Layer Change

StudentService

    StudentDto getStudentById(Long studentId);

Complete code:

package net.javaguides.sms.service;

import net.javaguides.sms.dto.StudentDto;

import java.util.List;

public interface StudentService {
    List<StudentDto> getAllStudents();

    void createStudent(StudentDto student);

    StudentDto getStudentById(Long studentId);
}

StudentServiceImpl change

    @Override
    public StudentDto getStudentById(Long studentId) {
        Student student = studentRepository.findById(studentId).get();
        StudentDto studentDto = StudentMapper.mapToStudentDto(student);
        return studentDto;
    }

Complete code:

package net.javaguides.sms.service.impl;

import net.javaguides.sms.dto.StudentDto;
import net.javaguides.sms.entity.Student;
import net.javaguides.sms.mapper.StudentMapper;
import net.javaguides.sms.repository.StudentRepository;
import net.javaguides.sms.service.StudentService;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.stream.Collectors;

@Service
public class StudentServiceImpl implements StudentService {

    private StudentRepository studentRepository;

    public StudentServiceImpl(StudentRepository studentRepository) {
        this.studentRepository = studentRepository;
    }

    @Override
    public List<StudentDto> getAllStudents() {
        List<Student> students = studentRepository.findAll();
        List<StudentDto> studentDtos = students.stream()
                .map((student) -> StudentMapper.mapToStudentDto(student))
                .collect(Collectors.toList());
        return studentDtos;
    }

    @Override
    public void createStudent(StudentDto studentDto) {
        Student student = StudentMapper.mapToStudent(studentDto);
        studentRepository.save(student);
    }

    @Override
    public StudentDto getStudentById(Long studentId) {
        Student student = studentRepository.findById(studentId).get();
        StudentDto studentDto = StudentMapper.mapToStudentDto(student);
        return studentDto;
    }
}