Implement student page

src/main/java/id/ac/ui/cs/advprog/tutorial0/controller/StudentController.java

+package id.ac.ui.cs.advprog.tutorial0.controller;
+
+import id.ac.ui.cs.advprog.tutorial0.exception.DuplicateStudentNameException;
+import id.ac.ui.cs.advprog.tutorial0.model.Student;
+import id.ac.ui.cs.advprog.tutorial0.service.StudentService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@Controller
+@RequestMapping("/student")
+public class StudentController {
+
+    @Autowired
+    private StudentService service;
+
+    @GetMapping("/list")
+    public String studentListPage(Model model) {
+        List<Student> allStudents = service.findAll();
+        model.addAttribute("students", allStudents);
+        return "studentList";
+    }
+
+    @GetMapping("/create")
+    public String createStudentPage(Model model) {
+        Student student = new Student();
+        model.addAttribute("student", student);
+        return "createStudent";
+    }
+
+    @PostMapping("/create")
+    public String createStudentPost(@ModelAttribute Student student, Model model) {
+        try {
+            service.create(student);
+        } catch (DuplicateStudentNameException e) {
+            model.addAttribute("error", e);
+            model.addAttribute("student", student);
+            return "createStudent";
+        }
+        return "redirect:list";
+    }
+
+}

src/main/java/id/ac/ui/cs/advprog/tutorial0/exception/DuplicateStudentNameException.java

+package id.ac.ui.cs.advprog.tutorial0.exception;
+
+public class DuplicateStudentNameException extends RuntimeException{
+    public DuplicateStudentNameException(String studentName) {
+        super(String.format("The student name %s is a duplicate!",studentName));
+    }
+}

src/main/java/id/ac/ui/cs/advprog/tutorial0/model/Student.java

+package id.ac.ui.cs.advprog.tutorial0.model;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter @Setter
+public class Student {
+    private String name;
+    private String npm;
+    private String address;
+
+}

src/main/java/id/ac/ui/cs/advprog/tutorial0/repository/StudentRepository.java

+package id.ac.ui.cs.advprog.tutorial0.repository;
+
+import id.ac.ui.cs.advprog.tutorial0.model.Student;
+import org.springframework.stereotype.Repository;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.Iterator;
+import java.util.List;
+
+@Repository
+public class StudentRepository {
+
+    private List<Student> studentsInMemory = new ArrayList<>();
+
+    public Student create(Student student) {
+        studentsInMemory.add(student);
+        return student;
+    }
+
+    public Iterator<Student> findAll() {
+        return studentsInMemory.iterator();
+    }
+}

src/main/java/id/ac/ui/cs/advprog/tutorial0/service/StudentService.java

+package id.ac.ui.cs.advprog.tutorial0.service;
+
+import id.ac.ui.cs.advprog.tutorial0.model.Student;
+
+import java.util.List;
+
+public interface StudentService {
+
+    public Student create(Student student);
+    public List<Student> findAll();
+}

src/main/java/id/ac/ui/cs/advprog/tutorial0/service/StudentServiceImpl.java

+package id.ac.ui.cs.advprog.tutorial0.service;
+
+import id.ac.ui.cs.advprog.tutorial0.exception.DuplicateStudentNameException;
+import id.ac.ui.cs.advprog.tutorial0.model.Student;
+import id.ac.ui.cs.advprog.tutorial0.repository.StudentRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+@Service
+public class StudentServiceImpl implements StudentService {
+
+    @Autowired
+    private StudentRepository studentRepository;
+
+    @Override
+    public Student create(Student student) {
+        validateName(student);
+        generateNPM(student);
+        studentRepository.create(student);
+        return student;
+    }
+
+    private void validateName(Student student) {
+        List<Student> allStudents = findAll();
+        for(Student dbStudent: allStudents) {
+            if(dbStudent.getName().equals(student.getName())) {
+                throw new DuplicateStudentNameException(student.getName());
+            }
+        }
+
+    }
+
+    private void generateNPM(Student student) {
+        StringBuilder stringBuilder = new StringBuilder();
+        for (char letter: student.getName().toCharArray()) {
+            stringBuilder.append(String.valueOf((int)letter));
+        }
+        String npm = stringBuilder.toString();
+        student.setNpm(npm);
+    }
+
+    @Override
+    public List<Student> findAll() {
+        Iterator<Student> studentIterator = studentRepository.findAll();
+        List<Student> allStudents = new ArrayList<>();
+        studentIterator.forEachRemaining(allStudents::add);
+        return allStudents;
+    }
+}
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src/main/resources/templates/createStudent.html

+<!DOCTYPE html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head>
+    <meta charset="UTF-8">
+    <title>Create new Student</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
+</head>
+<body>
+<h3>Create new Student</h3>
+<div th:if="${error!=null}" class="alert alert-danger" role="alert">
+    Duplicate student name
+</div>
+<form th:action="@{/student/create}" th:object="${student}" method="post">
+    <div class="form-group">
+        <label for="nameInput">Name</label>
+        <input th:field="*{name}" type="text" class="form-control" id="nameInput" aria-describedby="nameHelp" placeholder="Enter student' name">
+        <small id="nameHelp" class="form-text text-muted">Please enter unique name.</small>
+    </div>
+    <div class="form-group">
+        <label for="addressTextarea">Address</label>
+        <textarea th:field="*{address}" class="form-control" id="addressTextarea" rows="3"></textarea>
+    </div>
+    <button type="submit" class="btn btn-primary">Submit</button>
+</form>
+<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>
+</body>
+</html>
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src/main/resources/templates/studentList.html

+<!DOCTYPE html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head>
+  <meta charset="UTF-8">
+  <title>Student List</title>
+  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
+</head>
+<body>
+
+<h2>Student' List</h2>
+<a th:href="@{/student/create}" class="btn btn-primary btn-sm mb-3" >Create student</a>
+
+<table class="table">
+  <thead>
+  <tr>
+    <th scope="col">Name</th>
+    <th scope="col">NPM</th>
+    <th scope="col">Address</th>
+  </tr>
+  </thead>
+  <tbody th:each="student: ${students}">
+  <tr>
+    <td th:text="${student.name}"></td>
+    <td th:text="${student.npm}"></td>
+    <td th:text="${student.address}"></td>
+  </tr>
+
+  </tbody>
+</table>
+
+
+<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p" crossorigin="anonymous"></script>
+</body>
+</html>
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