Update added deleteTeachersWithoutSubject method for Teacher entity

src/main/java/cz/cvut/fit/tjv/seidlpet/semestralka/business/TeacherService.java

@@ -10,4 +10,5 @@ public interface TeacherService extends CrudService<Teacher, TeacherCreateDTO>{
     List<Teacher> findByFirstNameAndLastName(String firstName, String lastName);
     List<Teacher> findAllByFirstName(String firstName);
     List<Teacher> findAllByLastName(String lastName);
+    void deleteTeachersWithoutSubjects();
 }

src/main/java/cz/cvut/fit/tjv/seidlpet/semestralka/business/TeacherServiceImpl.java

 package cz.cvut.fit.tjv.seidlpet.semestralka.business;
+import cz.cvut.fit.tjv.seidlpet.semestralka.data.SubjectRepository;
 import cz.cvut.fit.tjv.seidlpet.semestralka.data.TeacherRepository;
 import cz.cvut.fit.tjv.seidlpet.semestralka.data.dto.TeacherCreateDTO;
+import cz.cvut.fit.tjv.seidlpet.semestralka.data.entity.Subject;
 import cz.cvut.fit.tjv.seidlpet.semestralka.data.entity.Teacher;
 import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.stereotype.Service;
@@ -15,9 +17,11 @@ import java.util.Optional;
 @Transactional
 public class TeacherServiceImpl implements TeacherService {
     private final TeacherRepository teacherRepository;
-    public TeacherServiceImpl(TeacherRepository teacherRepository) {
+    private final SubjectRepository subjectRepository;
+    public TeacherServiceImpl(TeacherRepository teacherRepository, SubjectRepository subjectRepository) {
         this.teacherRepository = teacherRepository;
+        this.subjectRepository = subjectRepository;
     }
     public Teacher create(Teacher teacher) {
@@ -61,4 +65,20 @@ public class TeacherServiceImpl implements TeacherService {
     public void deleteById(int id) {
         teacherRepository.deleteById(id);
     }
+
+    public void deleteTeachersWithoutSubjects() {
+        List<Subject> subjects = subjectRepository.findAll();
+        List<Teacher> teachers = findAll();
+        for (Teacher teacher : teachers) {
+            boolean remove = true;
+            for (Subject subject : subjects) {
+                if (teacher == subject.getTeacher()) {
+                    remove = false;
+                    break;
+                }
+            }
+            if (remove)
+                delete(teacher);
+        }
+    }
 }

src/main/java/cz/cvut/fit/tjv/seidlpet/semestralka/controller/TeacherController.java

@@ -67,6 +67,15 @@ public class TeacherController {
         }
     }
+    @DeleteMapping("/no-subject")
+    public void deleteTeachersWithoutSubjects() {
+        try {
+            teacherService.deleteTeachersWithoutSubjects();
+        } catch (IllegalArgumentException e) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+        }
+    }
+
     private TeacherDTO toDTO(Teacher teacher) {
         return new TeacherDTO(teacher.getId(),teacher.getFirstName(),teacher.getLastName());
     }