Осталось добавить взаимодействие между сущностями

src/main/java/ru/IP_LabWorks/IP/University/Model/Group.java

@@ -2,6 +2,7 @@ package ru.IP_LabWorks.IP.University.Model;
 
 import jakarta.persistence.*;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 
@@ -12,12 +13,19 @@ public class Group {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
     private String name;
-    @OneToMany
-    @JoinTable(name = "students_in_groups",
-            joinColumns = @JoinColumn(name = "group_id"),
-            inverseJoinColumns = @JoinColumn(name = "student_id"))
+    @OneToMany(fetch = FetchType.EAGER)
     private List<Student> students;
 
+    @ManyToMany
+    private List<Subject> subjects;
+
+    public Group() {
+    }
+
+    public Group(String name) {
+        this.name = name;
+    }
+
     public Long getId() { return id; }
     public String getName() { return name; }
     public void setName(String name) { this.name = name; }
@@ -42,4 +50,22 @@ public class Group {
                 ", name='" + name + '\'' +
                 '}';
     }
+
+    public List<Student> getStudents(){
+        return students;
+    }
+
+    public void addStudent(Student student){
+        if (students == null)
+            students = new ArrayList<>();
+        students.add(student);
+    }
+
+    public List<Subject> getSubjects() { return subjects; }
+
+    public void addSubject(Subject subject){
+        if (subjects == null)
+            subjects = new ArrayList<>();
+        subjects.add(subject);
+    }
 }

src/main/java/ru/IP_LabWorks/IP/University/Model/Student.java

@@ -1,6 +1,7 @@
 package ru.IP_LabWorks.IP.University.Model;
 import jakarta.persistence.*;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 
@@ -12,11 +13,6 @@ public class Student {
     private Long id;
     private String name;
     private Integer age;
-    @ManyToMany(cascade = CascadeType.ALL)
-    @JoinTable(name = "student_subject",
-            joinColumns = @JoinColumn(name = "student_id"),
-            inverseJoinColumns = @JoinColumn(name = "subject_id"))
-    private List<Subject> subjects;
 
     public Student() {
     }

src/main/java/ru/IP_LabWorks/IP/University/Model/Subject.java

@@ -12,8 +12,8 @@ public class Subject {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
     private String name;
-    @ManyToMany(mappedBy = "subjects")
-    private List<Student> students;
+    @ManyToMany
+    private List<Group> groups;
 
     public Subject() {
     }
@@ -46,4 +46,9 @@ public class Subject {
                 ", name='" + name + '\'' +
                 '}';
     }
+
+    public List<Group> getGroups() {
+        return groups;
+    }
+
 }

src/main/java/ru/IP_LabWorks/IP/University/Service/GroupService.java

@@ -1,4 +1,84 @@
 package ru.IP_LabWorks.IP.University.Service;
 
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.EntityNotFoundException;
+import jakarta.persistence.PersistenceContext;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.stereotype.Service;
+import org.springframework.util.StringUtils;
+import ru.IP_LabWorks.IP.University.Model.Group;
+import ru.IP_LabWorks.IP.University.Model.Student;
+import ru.IP_LabWorks.IP.University.Model.Subject;
+
+import java.util.List;
+
+@Service
 public class GroupService {
+    @PersistenceContext
+    private EntityManager em;
+
+    @Transactional
+    public Group addGroup(String name){
+        if (!StringUtils.hasText(name)) {
+            throw new IllegalArgumentException("Group name is null or empty");
+        }
+        final Group group = new Group(name);
+        em.persist(group);
+        return group;
+    }
+
+    @Transactional(readOnly  = true)
+    public Group findGroup(Long id){
+        final Group group = em.find(Group.class, id);
+        if (group == null) {
+            throw new EntityNotFoundException(String.format("Group with id [%s] is not found", id));
+        }
+        return group;
+    }
+
+    @Transactional(readOnly = true)
+    public List<Group> findAllGroups() {
+        return em.createQuery("select s from Group s", Group.class).getResultList();
+    }
+
+    @Transactional
+    public Group updateGroup(Long id, String name) {
+        if (!StringUtils.hasText(name)) {
+            throw new IllegalArgumentException("Group name is null or empty");
+        }
+        final Group currentGroup = findGroup(id);
+        currentGroup.setName(name);
+        return em.merge(currentGroup);
+    }
+
+    @Transactional
+    public Group deleteGroup(Long id) {
+        final Group currentGroup = findGroup(id);
+        em.remove(currentGroup);
+        return currentGroup;
+    }
+
+    @Transactional
+    public void deleteAllGroups() {
+        em.createQuery("delete from Group").executeUpdate();
+    }
+
+    @Transactional
+    public Group deleteStudentInGroup(Long id, Student student) {
+        final Group currentGroup = findGroup(id);
+        final Student currentStudent = em.find(Student.class, student.getId());
+        currentGroup.getStudents().remove(currentStudent);
+        em.merge(currentStudent);
+        return em.merge(currentGroup);
+    }
+
+    public List<Student> findStudentsInGroup(Long id){
+        final Group findGroup = findGroup(id);
+        return findGroup.getStudents();
+    }
+
+    public List<Subject> findSubjectsInGroup(Long id){
+        final Group findGroup = findGroup(id);
+        return findGroup.getSubjects();
+    }
 }

src/main/java/ru/IP_LabWorks/IP/University/Service/StudentService.java

@@ -1,6 +1,5 @@
 package ru.IP_LabWorks.IP.University.Service;
 
-import jakarta.persistence.Entity;
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.EntityNotFoundException;
 import jakarta.persistence.PersistenceContext;
@@ -8,6 +7,7 @@ import org.springframework.transaction.annotation.Transactional;
 import org.springframework.stereotype.Service;
 import org.springframework.util.StringUtils;
 import ru.IP_LabWorks.IP.University.Model.Student;
+import ru.IP_LabWorks.IP.University.Model.Subject;
 
 import java.util.List;
 

src/main/java/ru/IP_LabWorks/IP/University/Service/SubjectService.java

@@ -0,0 +1,64 @@
+package ru.IP_LabWorks.IP.University.Service;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.EntityNotFoundException;
+import jakarta.persistence.PersistenceContext;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.StringUtils;
+import ru.IP_LabWorks.IP.University.Model.Group;
+import ru.IP_LabWorks.IP.University.Model.Subject;
+
+import java.util.List;
+
+@Service
+public class SubjectService {
+    @PersistenceContext
+    private EntityManager em;
+
+    @Transactional
+    public Subject addSubject(String name){
+        if (!StringUtils.hasText(name)) {
+            throw new IllegalArgumentException("Subject name is null or empty");
+        }
+        final Subject subject = new Subject(name);
+        em.persist(subject);
+        return subject;
+    }
+
+    @Transactional(readOnly  = true)
+    public Subject findSubject(Long id){
+        final Subject subject = em.find(Subject.class, id);
+        if (subject == null) {
+            throw new EntityNotFoundException(String.format("Subject with id [%s] is not found", id));
+        }
+        return subject;
+    }
+
+    @Transactional(readOnly = true)
+    public List<Subject> findAllSubjects() {
+        return em.createQuery("select s from Subject s", Subject.class).getResultList();
+    }
+
+    @Transactional
+    public Subject updateSubject(Long id, String name) {
+        if (!StringUtils.hasText(name)) {
+            throw new IllegalArgumentException("Subject name is null or empty");
+        }
+        final Subject currentSubject = findSubject(id);
+        currentSubject.setName(name);
+        return em.merge(currentSubject);
+    }
+
+    @Transactional
+    public Subject deleteSubject(Long id) {
+        final Subject currentSubject = findSubject(id);
+        em.remove(currentSubject);
+        return currentSubject;
+    }
+
+    @Transactional
+    public void deleteAllSubjects() {
+        em.createQuery("delete from Subject").executeUpdate();
+    }
+}

src/test/java/ru/IP_LabWorks/IP/GroupServiceTests.java

@@ -0,0 +1,80 @@
+package ru.IP_LabWorks.IP;
+
+import jakarta.persistence.EntityNotFoundException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import ru.IP_LabWorks.IP.University.Model.Group;
+import ru.IP_LabWorks.IP.University.Model.Student;
+import ru.IP_LabWorks.IP.University.Service.GroupService;
+import ru.IP_LabWorks.IP.University.Service.StudentService;
+
+import java.util.List;
+
+@SpringBootTest
+public class GroupServiceTests {
+    @Autowired
+    private GroupService groupService;
+
+    @Autowired
+    private StudentService studentService;
+
+    @Test
+    void TestAddGroup(){
+        groupService.deleteAllGroups();
+        final Group group = groupService.addGroup("ПИбд-21");
+        Assertions.assertNotNull(group.getId());
+    }
+
+    @Test
+    void TestFindGroup(){
+        groupService.deleteAllGroups();
+        final Group group = groupService.addGroup("ПИбд-21");
+
+        final Group findGroup = groupService.findGroup(group.getId());
+        Assertions.assertEquals(group, findGroup);
+    }
+
+    @Test
+    void TestFindAllGroup(){
+        groupService.deleteAllGroups();
+        final Group group1 = groupService.addGroup("ПИбд-21");
+        final Group group2 = groupService.addGroup("ПИбд-22");
+
+        final List<Group> groups = groupService.findAllGroups();
+        Assertions.assertEquals(groups.size(), 2);
+    }
+
+    @Test
+    void TestUpdateGroup(){
+        groupService.deleteAllGroups();
+        Group group = groupService.addGroup("ПИбд-21");
+
+        group = groupService.updateGroup(group.getId(), "ПИбд-22");
+        Assertions.assertEquals(group.getName(), "ПИбд-22");
+    }
+
+    @Test
+    void TestDeleteGroup(){
+        groupService.deleteAllGroups();
+        Group group = groupService.addGroup("ПИбд-21");
+        groupService.deleteGroup(group.getId());
+        Assertions.assertThrows(EntityNotFoundException.class, () -> {
+            groupService.findGroup(group.getId());
+        });
+    }
+
+    @Test
+    void TestFindStudentsInGroup(){
+        groupService.deleteAllGroups();
+        Student student1 = studentService.addStudent("Марков Данил Павлович", 19);
+        Student student2 = studentService.addStudent("Емельянов Артём Сергеевич", 19);
+        Group group = groupService.addGroup("ПИбд-21");
+        group.addStudent(student1);
+        group.addStudent(student2);
+        final List<Student> students = groupService.findStudentsInGroup(group.getId());
+        System.out.println("DFGSDFGSDFGSDFG" + students.size());
+        Assertions.assertEquals(students.size(), 2);
+    }
+}

src/test/java/ru/IP_LabWorks/IP/StudentServiceTests.java

@@ -0,0 +1,65 @@
+package ru.IP_LabWorks.IP;
+
+import jakarta.persistence.EntityNotFoundException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import ru.IP_LabWorks.IP.University.Model.Student;
+import ru.IP_LabWorks.IP.University.Model.Subject;
+import ru.IP_LabWorks.IP.University.Service.StudentService;
+import ru.IP_LabWorks.IP.University.Service.SubjectService;
+
+import java.util.List;
+
+@SpringBootTest
+public class StudentServiceTests {
+    @Autowired
+    private StudentService studentService;
+
+    @Test
+    void TestAddStudent(){
+        studentService.deleteAllStudent();
+        final Student student = studentService.addStudent("Марков Данил Павлович", 19);
+        Assertions.assertNotNull(student.getId());
+    }
+
+    @Test
+    void TestFindStudent(){
+        studentService.deleteAllStudent();
+        final Student student = studentService.addStudent("Марков Данил Павлович", 19);
+
+        final Student findStudent = studentService.findStudent(student.getId());
+        Assertions.assertEquals(student, findStudent);
+    }
+
+    @Test
+    void TestFindAllStudent(){
+        studentService.deleteAllStudent();
+        final Student student1 = studentService.addStudent("Марков Данил Павлович", 19);
+
+        final Student student2 = studentService.addStudent("Емельянов Артём Сергеевич", 19);
+
+        final List<Student> students = studentService.findAllStudents();
+        Assertions.assertEquals(students.size(), 2);
+    }
+
+    @Test
+    void TestUpdateStudent(){
+        studentService.deleteAllStudent();
+        Student student = studentService.addStudent("Марков Данил Павлович", 19);
+
+        student = studentService.updateStudent(student.getId(), "Емельянов Артём Сергеевич", 19);
+        Assertions.assertEquals(student.getName(), "Емельянов Артём Сергеевич");
+    }
+
+    @Test
+    void TestDeleteStudent(){
+        studentService.deleteAllStudent();
+        Student student = studentService.addStudent("Марков Данил Павлович", 19);
+        studentService.deleteStudent(student.getId());
+        Assertions.assertThrows(EntityNotFoundException.class, () -> {
+            studentService.findStudent(student.getId());
+        });
+    }
+}

src/test/java/ru/IP_LabWorks/IP/SubjectServiceTests.java

@@ -0,0 +1,62 @@
+package ru.IP_LabWorks.IP;
+
+import jakarta.persistence.EntityNotFoundException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import ru.IP_LabWorks.IP.University.Model.Subject;
+import ru.IP_LabWorks.IP.University.Service.SubjectService;
+
+import java.util.List;
+
+@SpringBootTest
+public class SubjectServiceTests {
+    @Autowired
+    private SubjectService subjectService;
+
+    @Test
+    void TestAddSubject(){
+        subjectService.deleteAllSubjects();
+        final Subject subject = subjectService.addSubject("Философия");
+        Assertions.assertNotNull(subject.getId());
+    }
+
+    @Test
+    void TestFindSubject(){
+        subjectService.deleteAllSubjects();
+        final Subject subject = subjectService.addSubject("Философия");
+
+        final Subject findSubject = subjectService.findSubject(subject.getId());
+        Assertions.assertEquals(subject, findSubject);
+    }
+
+    @Test
+    void TestFindAllSubject(){
+        subjectService.deleteAllSubjects();
+        final Subject subject1 = subjectService.addSubject("Философия");
+        final Subject subject2 = subjectService.addSubject("Математика");
+
+        final List<Subject> subjects = subjectService.findAllSubjects();
+        Assertions.assertEquals(subjects.size(), 2);
+    }
+
+    @Test
+    void TestUpdateSubject(){
+        subjectService.deleteAllSubjects();
+        Subject subject = subjectService.addSubject("Философия");
+
+        subject = subjectService.updateSubject(subject.getId(), "Математика");
+        Assertions.assertEquals(subject.getName(), "Математика");
+    }
+
+    @Test
+    void TestDeleteSubject(){
+        subjectService.deleteAllSubjects();
+        Subject subject = subjectService.addSubject("Математика");
+        subjectService.deleteSubject(subject.getId());
+        Assertions.assertThrows(EntityNotFoundException.class, () -> {
+            subjectService.findSubject(subject.getId());
+        });
+    }
+}