1 files changed, 69 insertions, 0 deletions
diff --git a/src/main/java/com/odiparpack/back/odiparback/student/StudentService.java b/src/main/java/com/odiparpack/back/odiparback/student/StudentService.java
new file mode 100644
index 0000000..6831dd8
--- /dev/null
+++ b/src/main/java/com/odiparpack/back/odiparback/student/StudentService.java
@@ -0,0 +1,69 @@
+package com.odiparpack.back.odiparback.student;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import javax.transaction.Transactional;
+import java.time.LocalDate;
+import java.time.Month;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+
+@Service
+public class StudentService {
+
+    private final StudentRepository studentRepository;
+
+    @Autowired
+    public StudentService(StudentRepository studentRepository) {
+        this.studentRepository = studentRepository;
+    }
+
+    public List<Student> getStudents() {
+        return studentRepository.findAll();
+    }
+
+    public void addNewStudent(Student student) {
+        /* check if the email is already registered, if so throw error */
+        Optional<Student> studentOptional =
+                studentRepository.findStudentByEmail(student.getEmail());
+        if (studentOptional.isPresent()) {
+            throw new IllegalStateException("email taken");
+            // email validation is also possible here
+        }
+        studentRepository.save(student);
+    }
+
+    public void deleteStudent(Long studentId) {
+        boolean exists = studentRepository.existsById(studentId);
+        if (!exists) {
+            throw new IllegalStateException(
+                    "student with id " + studentId + " does not exists");
+        }
+        studentRepository.deleteById(studentId);
+    }
+
+    // "The entity goes into a managed state".  Changes are seaved automatically
+    @Transactional
+    public void updateStudent(Long studentId, String name, String email) {
+        Student student = studentRepository.findById(studentId)
+                .orElseThrow(() -> new IllegalStateException(
+                        "student with id " + studentId + " does not exist"
+                ));
+        /* check that attributes are valid before updating object/record */
+        if (name != null && name.length() > 0 &&
+                !Objects.equals(student.getName(), name)) {
+            student.setName(name);
+        }
+        if (email != null && email.length() > 0 &&
+                !Objects.equals(student.getName(), email)) {
+            Optional<Student> studentOptional = studentRepository
+                    .findStudentByEmail(email);
+            if (studentOptional.isPresent()) {
+                throw new IllegalStateException("email taken");
+            }
+            student.setEmail(email);
+        }
+    }
+}