- went over PUT, POST, and DELETE mappings

- went over using the RequestBody and RequestParams in RestControllers
- went over writing business logic in Service Layer classes

src/main/java/com/example/springcrashcourse/student/StudentController.java

@@ -1,9 +1,14 @@
 package com.example.springcrashcourse.student;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
 import com.example.springcrashcourse.student.Student;
@@ -11,6 +16,7 @@ import com.example.springcrashcourse.student.Student;
 import java.time.LocalDate;
 import java.time.Month;
 import java.util.List;
+import java.util.Optional;
 
 @RestController
 @RequestMapping("/api/v1")
@@ -28,5 +34,23 @@ public class StudentController {
         return studentService.getStudents();
     }
 
+    @PostMapping(path = "/student/registerStudent")
+    public void registerStudent(@RequestBody Student student) {
+        studentService.addStudent(student);
+    }
+
+    @DeleteMapping(path = "/student/{studentId}")
+    public void deleteStudent(@PathVariable("studentId") Long studentId) {
+        studentService.deleteStudent(studentId);
+    }
+
+    @PutMapping(path = "/student/{studentId}")
+    public void updateStudent(
+        @PathVariable("studentId") Long studentId,
+        @RequestParam(required = false) String name,
+        @RequestParam(required = false) String email
+    ) {
+        studentService.updateStudent(studentId, name, email);
+    }
 
 }

src/main/java/com/example/springcrashcourse/student/StudentRepository.java

@@ -1,9 +1,16 @@
 package com.example.springcrashcourse.student;
 
+import java.util.Optional;
+
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 @Repository
 public interface StudentRepository extends JpaRepository<Student, Long> {
+
+    // SELECT * FROM student WHERE email = ?1;
+    @Query("SELECT s FROM Student s WHERE s.email = ?1")
+    Optional<Student> findStudentByEmail(String email);
     
 }

src/main/java/com/example/springcrashcourse/student/StudentService.java

@@ -3,10 +3,13 @@ package com.example.springcrashcourse.student;
 import java.time.LocalDate;
 import java.time.Month;
 import java.util.List;
+import java.util.Optional;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
+import jakarta.transaction.Transactional;
+
 @Service
 public class StudentService {
 
@@ -20,4 +23,51 @@ public class StudentService {
     public List<Student> getStudents() {
         return studentRepository.findAll();
     }
+
+    public void addStudent(Student student) {
+        System.out.println(student);
+        Optional<Student> studentOptional = studentRepository
+            .findStudentByEmail(student.getEmail());
+
+        if(studentOptional.isPresent()) {
+            throw new IllegalStateException("Email Taken");
+        }
+        studentRepository.save(student);
+    }
+
+    public void deleteStudent(Long studentId) {
+        boolean studentExists = studentRepository.existsById(studentId);
+
+        if(!studentExists) {
+            throw new IllegalStateException("Student with id " + studentId + " does not exists");
+        }
+        if(studentExists) {
+            studentRepository.deleteById(studentId);
+        }
+    }
+
+    @Transactional
+    public void updateStudent(Long studentId, String name, String email) {
+        Optional<Student> studentOptional = studentRepository.findById(studentId);
+
+        if(!studentOptional.isPresent()) {
+            throw new IllegalStateException("Student with id " + studentId + " does not exists");
+        }
+
+        Student student = studentOptional.get();
+        
+        if (name != null) student.setName(name);
+
+        if (email != null) {
+            Optional<Student> studentThatExistsAlready = studentRepository
+                .findStudentByEmail(student.getEmail());
+
+            if(studentThatExistsAlready.isPresent()) {
+                throw new IllegalStateException("Email Taken");
+            }
+            student.setEmail(email);
+        }
+
+        studentRepository.save(student);
+    }
 }

src/main/resources/application.properties

@@ -1,6 +1,6 @@
 
-spring.datasource.url=jdbc:postgresql://localhost:5432/student
+spring.datasource.url=jdbc:postgresql://localhost:3636/student
-spring.datasource.username=postgres
+spring.datasource.username=okechi
 spring.datasource.password=testing
 spring.jpa.hibernate.ddl-auto=create-drop
 spring.jpa.show-sql=true