Fix UserService#updateStudent to copy all non-null fields from request body

src/main/java/com/student/details/models/Student.java

@@ -3,6 +3,7 @@ package com.student.details.models;
 import lombok.Data;
 import javax.persistence.*;
 import javax.validation.constraints.NotNull;
+import java.lang.reflect.Field;
 import java.time.LocalDate;
 
 @Entity
@@ -21,4 +22,18 @@ public class Student {
   
   @NotNull
   private LocalDate dateOfBirth;
+  
+  public void copyFields(Student sourceStudent) {
+    try {
+      for (Field field : sourceStudent.getClass().getDeclaredFields()) {
+        String fieldName = field.getName();
+        Object sourceValue = field.get(sourceStudent);
+        
+        if (!fieldName.equals("id") && null != sourceValue) {
+          Field destField = this.getClass().getDeclaredField(fieldName);
+          destField.set(this, sourceValue);
+        }
+      }
+    } catch (Exception ignore) { }
+  }
 }

src/main/java/com/student/details/services/StudentService.java

@@ -44,12 +44,8 @@ public class StudentService {
     public Student updateStudent(Long studentId, Student studentDetails) throws ResourceNotFoundException {
         Student student = studentRepository.findById(studentId)
                 .orElseThrow(() -> new ResourceNotFoundException("Student id: " + studentId + " not found"));
-
-        student.setFirstName(studentDetails.getFirstName());
-        student.setLastName(studentDetails.getLastName());
-
-        Student updatedStudent = studentRepository.save(student);
-        return updatedStudent;
+        student.copyFields(studentDetails);
+        return studentRepository.save(student);
 
     }