issue with interface io.javabrains.repository.DepartmentRepository

issue with interface io.javabrains.repository.DepartmentRepository - java

I was trying to build CRM for university.But when I tried to auto built table within the hibernate,it displays me the following error:
Not managed type interface io.javabrains.repository.DepartmentRepository
I just tried to add Repository annotation to every other Repo classes but no results were achieved
Department Category.class
package io.javabrains.Entities;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import lombok.Data;
import lombok.EqualsAndHashCode;
#Data
#EqualsAndHashCode(exclude="Student")
#Entity
#Table(name="department")
public class DepartmentCategory {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
public int getId() {
return id;
}
public DepartmentCategory(int id, String name, Set<Student> students) {
super();
this.id = id;
this.name = name;
this.students = students;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
private String name;
#OneToMany(mappedBy = "departmentCategory",cascade = CascadeType.ALL)
private Set<Student>students;
}
DepartmentRepository.class
package io.javabrains.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
#Repository
public interface DepartmentRepository extends JpaRepository<DepartmentRepository, Integer> {
}
CrmSchoolApplicaton.class
package io.javabrains;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
#SpringBootApplication
public class CrmSchoolApplication {
public static void main(String[] args) {
SpringApplication.run(CrmSchoolApplication.class, args);
}
}
...............

try to change your JpaRepository :
public interface DepartmentRepository extends JpaRepository<Department, Integer>
instead of
public interface DepartmentRepository extends JpaRepository<DepartmentRepository, Integer>

Related

Postman is returning a 404 error on my Spring Boot API

I've built a spring boot rest api. However, when I try to test it in Postman, I am getting a 404 error. I have linked the code below. Please note that there might be a random #component annotation in some files. This was my tired brain trying anything it can.
Student.java
package StudentModel;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
#Data
#AllArgsConstructor
#NoArgsConstructor
#Entity
#Table(name = "Student")
public class Student {
public enum status {
PAID,
UNPAID,
PARTIAL
}
#Column
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private long Id;
#Column(nullable = false)
private String FirstName;
#Column(nullable = false)
private String LastName;
#Column(nullable = false)
private long Phone;
#Column(nullable = false)
private String Email;
#Column(nullable = false)
private status PaymentStatus;
public long getId() {
return Id;
}
public void setId(long id) {
Id = id;
}
public String getFirstName() {
return FirstName;
}
public void setFirstName(String firstName) {
FirstName = firstName;
}
public String getLastName() {
return LastName;
}
public void setLastName(String lastName) {
LastName = lastName;
}
public long getPhone() {
return Phone;
}
public void setPhone(long phone) {
Phone = phone;
}
public String getEmail() {
return Email;
}
public void setEmail(String email) {
Email = email;
}
public status getPaymentStatus() {
return PaymentStatus;
}
public void setPaymentStatus(status paymentStatus) {
PaymentStatus = paymentStatus;
}
}
StudentController.java
package StudentController;
import java.util.List;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
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.RestController;
import StudentModel.Student;
import StudentService.StudentService;
#Component
#RestController
#RequestMapping("/api/v1")
public class StudentController {
#Autowired
private StudentService studentService;
#PostMapping("/api/v1/addStudent")
public Student addStudent(#RequestBody Student student) {
return studentService.saveStudent(student);
}
#PostMapping("/api/v1/addStudents")
public List<Student> addStudents(#RequestBody List<Student> students) {
return studentService.saveStudents(students);
}
#GetMapping("/api/v1/students")
public List<Student> findAllStudents(){
return studentService.getStudents();
}
#GetMapping("/api/v1/students/{id}")
public Student findStudentById(#PathVariable long id) {
return studentService.getStudentById(id);
}
#GetMapping("/api/v1/students/{name}")
public Student findStudentByFirstName(#PathVariable String FirstName) {
return studentService.getStudentByFirstName(FirstName);
}
#PutMapping("/api/v1/update")
public Student updateStudent(#RequestBody Student student) {
return studentService.updateStudent(student);
}
#DeleteMapping("/api/v1/delete/{id}")
public String deleteStudent(#PathVariable long id) {
return studentService.deleteStudent(id);
}
}
StudentService.java
package StudentService;
import java.util.List;
import java.util.Optional;
import javax.transaction.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import StudentModel.Student;
import StudentRepository.StudentRepository;
#Component
#Service
#Transactional
public class StudentService {
#Autowired
private StudentRepository studentRepository;
public Student saveStudent(Student student) {
return studentRepository.save(student);
}
public List<Student> saveStudents(List<Student> students) {
return studentRepository.saveAll(students);
}
public List<Student> getStudents() {
return studentRepository.findAll();
}
public Student getStudentById(long id){
return studentRepository.getById(id);
}
public Student getStudentByFirstName(String FirstName){
return studentRepository.findByFirstName(FirstName);
}
public Student getStudentByLastName(String LastName){
return studentRepository.findByLastName(LastName);
}
public Student getStudentByEmail(String Email){
return studentRepository.findByEmail(Email);
}
public Student getStudentByPhone(long Phone){
return studentRepository.findByPhone(Phone);
}
public String deleteStudent(long id) {
studentRepository.deleteById(id);
return "Student Deleted";
}
public Student updateStudent (Student student) {
Student existingStudent = studentRepository.getById(student.getId());
existingStudent.setFirstName(student.getFirstName());
existingStudent.setLastName(student.getLastName());
existingStudent.setEmail(student.getEmail());
existingStudent.setPhone(student.getPhone());
existingStudent.setPaymentStatus(student.getPaymentStatus());
return studentRepository.save(existingStudent);
}
}
StudentRepository.java
package StudentRepository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Component;
import StudentModel.Student;
#Component
public interface StudentRepository extends JpaRepository <Student, Long>{
// Student saveStudent (Student student);
Student findByFirstName(String FirstName);
Student findByLastName(String LastName);
Student findByEmail(String Email);
Student findByPhone(long Phone);
// Student findById(long id);
}
StudentApplication.java
package com.BusyQA;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
#SpringBootApplication
#ComponentScan
public class BusyQaApplication extends SpringBootServletInitializer{
public static void main(String[] args) {
SpringApplication.run(BusyQaApplication.class, args);
}
}
Any help would be greatly appreciated. Thank you.

To make it work, you need some improvements:
For Controller (REST API requests):
remove #Component annotation;
remove /api/v1/ from request mappings;
add DTO to only transfer the required information;
fix the name of the variables, following the convention.
import java.util.ArrayList;
import java.util.List;
import com.example.demo.dto.StudentDTO;
import com.example.demo.entity.Student;
import com.example.demo.service.StudentService;
import org.springframework.web.bind.annotation.*;
#RestController
#RequestMapping("/api/v1")
public class StudentController {
private final StudentService studentService;
public StudentController(StudentService studentService) {
this.studentService = studentService;
}
#PostMapping("/addStudent")
public Student addStudent(#RequestBody StudentDTO studentDTO) {
Student student = new Student(studentDTO);
return studentService.saveStudent(student);
}
#PostMapping("/addStudents")
public List<Student> addStudents(#RequestBody List<Student> students) {
return studentService.saveStudents(students);
}
#GetMapping("/students")
public List<StudentDTO> findAllStudents() {
List<StudentDTO> studentDTOList = new ArrayList<>();
List<Student> studentList = studentService.getStudents();
for (Student student : studentList) {
StudentDTO studentDTO = new StudentDTO(student);
studentDTOList.add(studentDTO);
}
return studentDTOList;
}
#GetMapping("/students/id/{id}")
public Student findStudentById(#PathVariable long id) {
return studentService.getStudentById(id);
}
#GetMapping("/students/firstName/{firstName}")
public Student findStudentByFirstName(#PathVariable String firstName) {
return studentService.getStudentByFirstName(firstName);
}
#PutMapping("/update")
public Student updateStudent(#RequestBody StudentDTO studentDTO) {
Student student = new Student(studentDTO);
return studentService.updateStudent(student);
}
#DeleteMapping("/delete/{id}")
public String deleteStudent(#PathVariable long id) {
return studentService.deleteStudent(id);
}
}
For Service class (Business logic):
remove #Component annotation;
remove #Transactional annotation;
use findById() to retrieve an entity by its Id;
import java.util.List;
import java.util.Optional;
import com.example.demo.entity.Student;
import com.example.demo.repository.StudentRepository;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.persistence.EntityNotFoundException;
#Service
public class StudentService {
private final StudentRepository studentRepository;
public StudentService(StudentRepository studentRepository) {
this.studentRepository = studentRepository;
}
public Student saveStudent(Student student) {
return studentRepository.save(student);
}
public List<Student> saveStudents(List<Student> students) {
return studentRepository.saveAll(students);
}
public List<Student> getStudents() {
return studentRepository.findAll();
}
public Student getStudentById(long id) {
return studentRepository.findById(id).orElseThrow(EntityNotFoundException::new);
}
public Student getStudentByFirstName(String firstName) {
return studentRepository.findByFirstName(firstName);
}
public Student getStudentByLastName(String lastName) {
return studentRepository.findByLastName(lastName);
}
public Student getStudentByEmail(String email) {
return studentRepository.findByEmail(email);
}
public Student getStudentByPhone(long phone) {
return studentRepository.findByPhone(phone);
}
public String deleteStudent(long id) {
studentRepository.deleteById(id);
return "Student Deleted";
}
public Student updateStudent(Student student) {
Student existingStudent = studentRepository.getById(student.getId());
existingStudent.setFirstName(student.getFirstName());
existingStudent.setLastName(student.getLastName());
existingStudent.setEmail(student.getEmail());
existingStudent.setPhone(student.getPhone());
existingStudent.setPaymentStatus(student.getPaymentStatus());
return studentRepository.save(existingStudent);
}
}
The Model class:
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import com.example.demo.dto.StudentDTO;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.Builder;
#Data
#Builder
#AllArgsConstructor
#NoArgsConstructor
#Entity
public class Student {
public Student(StudentDTO studentDTO) {
this.id = studentDTO.getId();
this.firstName = studentDTO.getFirstName();
this.lastName = studentDTO.getLastName();
this.phone = studentDTO.getPhone();
this.email = studentDTO.getEmail();
this.paymentStatus = studentDTO.getPaymentStatus();
}
public enum Status {
PAID,
UNPAID,
PARTIAL
}
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column
private long id;
private String firstName;
private String lastName;
private long phone;
private String email;
private Status paymentStatus;
}
DTO class:
import com.example.demo.entity.Student;
import com.fasterxml.jackson.annotation.JsonInclude;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
import static com.fasterxml.jackson.annotation.JsonInclude.Include.NON_NULL;
#Builder
#Data
#NoArgsConstructor
#AllArgsConstructor
#JsonInclude(NON_NULL)
public class StudentDTO implements Serializable {
public StudentDTO(Student student) {
this.id = student.getId();
this.firstName = student.getFirstName();
this.lastName = student.getLastName();
this.phone = student.getPhone();
this.email = student.getEmail();
this.paymentStatus = student.getPaymentStatus();
}
private long id;
private String firstName;
private String lastName;
private long phone;
private String email;
private Student.Status paymentStatus;
}
The Repository class:
import com.example.demo.entity.Student;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
#Repository
public interface StudentRepository extends JpaRepository<Student, Long> {
Student findByFirstName(String firstName);
Student findByLastName(String lastName);
Student findByEmail(String email);
Student findByPhone(long phone);
}
and the main class of a Spring Boot application:
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
To test it, you can use endpoints by the same principle:
POST: localhost:8080/api/v1/addStudent
POST: localhost:8080/api/v1/addStudents
GET: localhost:8080/api/v1/students
GET: localhost:8080/api/v1/students/id/1
GET: localhost:8080/api/v1/students/firstName/testName
PUT: localhost:8080/api/v1/update
DELETE: localhost:8080/api/v1/delete/1

As Dilermando mentioned in the comments, your #RequestMapping("/api/v1") is setting its mapping, then you're extending onto that with #PostMapping("/api/v1/addStudent") making the address {url}/api/v1/api/v1/addStudent. You can resolve this by removing the /api/v1 from the Post/get mappings:
#RequestMapping("/api/v1")
public class StudentController {
#Autowired
private StudentService studentService;
#PostMapping("/addStudent")
public Student addStudent(#RequestBody Student student) {
return studentService.saveStudent(student);
}
...etc
}

There are 2 reason behind 404 not found
Problem 1
You main class is in com.BusyQA package and Controller class is in StudentController package so you have to scan controller class in main class.
Your StudentApplication.java class should become:
#SpringBootApplication
#ComponentScan(basePackageClasses = StudentController.class) // Scan the controller class in main class.
public class BusyQaApplication extends SpringBootServletInitializer{
public static void main(String[] args) {
SpringApplication.run(BusyQaApplication.class, args);
}
}
Problem 2
Remove pre path /api/v1 from all url mapping in controller. Now your mapping url should become
#RestController
#RequestMapping("/api/v1")
public class StudentController {
#Autowired
private StudentService studentService;
#PostMapping("/addStudent")
#PostMapping("/addStudents")
#GetMapping("/students")
#GetMapping("/students/{id}")
#GetMapping("/students/{name}")
#PutMapping("/update")
#DeleteMapping("/delete/{id}")
}
This is another mistake in your code:
Remove the #Component annotation from controller.
Remove the #Component annotation from Service class.
Remove the #Component annotation from Repository interface and add #Repository annotation.

Spring Boot "Failed to execute CommandLineRunner Error"

I tried to add One To Many Annotation to my spring boot project, but when I run my project I get "Failed to execute CommandLineRunner " error.
I wanted users in the user's table to have more than one city. So, I tried to add OneToMany Annotation.
You can see the error at the attachment.
User Class
package io.javabrains.springsecurity.jpa.models;
import com.spring.weather.*;
import java.util.*;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.OneToMany;
import javax.persistence.Table;
#Entity
#Table(name="app_user")
public class User {
#Id
#GeneratedValue(strategy =GenerationType.AUTO)
private int id;
private String userName;
private String password;
private boolean active;
private String role;
private String city;
#OneToMany(targetEntity = UserCity.class,cascade = CascadeType.ALL)
#JoinTable(name="USER_CITY",joinColumns=#JoinColumn(name="m_user_id"),
inverseJoinColumns=#JoinColumn(name="cityId"))
private List<UserCity> usercity;
public User() {
super();
// TODO Auto-generated constructor stub
}
public List<UserCity> getUsercity() {
return usercity;
}
public void setUsercity(List<UserCity> usercity) {
this.usercity = usercity;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
public String getRole() {
return role;
}
public void setRole(String role) {
this.role = role;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
}
User City Class
package io.javabrains.springsecurity.jpa.models;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
#Entity
#Table(name="user_city")
public class UserCity {
#Id
#GeneratedValue(strategy =GenerationType.AUTO)
private int cityId;
private String cityName;
public UserCity() {
super();
// TODO Auto-generated constructor stub
}
public UserCity(int cityId, String cityName, User mUser) {
super();
this.cityId = cityId;
this.cityName = cityName;
this.mUser = mUser;
}
#ManyToOne
private User mUser;
public int getCityId() {
return cityId;
}
public void setCityId(int cityId) {
this.cityId = cityId;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public User getmUser() {
return mUser;
}
public void setmUser(User mUser) {
this.mUser = mUser;
}
}
User Repository
package io.javabrains.springsecurity.jpa;
import java.util.Optional;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import io.javabrains.springsecurity.jpa.models.User;
public interface UserRepository extends JpaRepository<User, Integer> {
Optional<User> findByUserName(String userName);
}
User City Repository
package io.javabrains.springsecurity.jpa;
import org.springframework.data.jpa.repository.JpaRepository;
import io.javabrains.springsecurity.jpa.models.User;
import io.javabrains.springsecurity.jpa.models.UserCity;
public interface CityRepository extends JpaRepository<UserCity,id>{
}
Spring Application Class
package io.javabrains.springsecurity.jpa;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import com.spring.weather.WeatherService;
import io.javabrains.springsecurity.jpa.models.User;
import io.javabrains.springsecurity.jpa.models.UserCity;
#SpringBootApplication
#EnableJpaRepositories(basePackageClasses = UserRepository.class)
public class SpringsecurityApplication implements CommandLineRunner{
#Bean
public WeatherService ws() {
return new WeatherService ();
}
#Autowired
UserRepository userRepository;
CityRepository cityRepository;
public static void main(String[] args) {
SpringApplication.run(SpringsecurityApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
// TODO Auto-generated method stub
System.out.println("Application Running.");
User adminUser= new User();
UserCity ucity=new UserCity();
UserCity ucity2=new UserCity();
ucity.setCityName("amsterdam");
adminUser.setUserName("Admin");
adminUser.setPassword(new BCryptPasswordEncoder().encode("pass"));
adminUser.setRole("ROLE_ADMIN");
adminUser.setActive(true);
adminUser.setCity("bologna");
ucity.setmUser(adminUser);
userRepository.save(adminUser);
cityRepository.save(ucity);
User newUser= new User();
newUser.setUserName("User");
newUser.setPassword(new BCryptPasswordEncoder().encode("pass"));
newUser.setRole("ROLE_USER");
newUser.setActive(true);
newUser.setCity("maribor");
ucity2.setmUser(newUser);
userRepository.save(newUser);
cityRepository.save(ucity2);
}
}

The problem you are encountering, more specifically the NullPointerException at line 54 of your main application, is caused by the fact that the cityRepository is not
instantiated.
Looking through your configuration, I see that you only register the UserRepository with the #EnableJpaRepositories annotation.
Try adding also the CityRepository to the #EnableJpaRepositories, and also specify this bean as a candidate for autowiring( also add #Autowired to this bean, as you did for UserRepository)
For a good practice, following the MVC structure, it would be nice is all your spring repositories, the beans responsible for all CRUD operations with the database to be under the same package

findById() not working on spring boot and Jpa

My main class is :
package com.ashwin.jpafirst;
import com.ashwin.jpafirst.model.Person;
import com.ashwin.jpafirst.reposit.PersonJpaRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class JpafirstApplication implements CommandLineRunner {
private Logger logger= LoggerFactory.getLogger(this.getClass());
#Autowired
PersonJpaRepository personJpaRepository;
public static void main(String[] args)
{
SpringApplication.run(JpafirstApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
// TODO Auto-generated method stub
logger.info("User id is ",personJpaRepository.findById(2));
}
}
Person.java
package com.ashwin.jpafirst.model;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
#Entity
#Table(name="person")
public class Person {
#Id
#GeneratedValue
private int id;
#Column(name="name")
private String name;
private String location;
private Date dateOfBirth;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
public Date getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(Date dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
public Person(int id, String name, String location, Date dateOfBirth) {
this.id = id;
this.name = name;
this.location = location;
this.dateOfBirth = dateOfBirth;
}
public Person() {
}
}
my application properties is:
## Spring DATASOURCE (DataSourceAutoConfiguration & DataSourceProperties)
spring.datasource.url = jdbc:mysql://localhost:3306/jpaintro
spring.datasource.username = root
spring.datasource.password =
## Hibernate Properties
# The SQL dialect makes Hibernate generate better SQL for the chosen database
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect
# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto = update
PersonJpaRepository.java
package com.ashwin.jpafirst.reposit;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import com.ashwin.jpafirst.model.Person;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
#Repository
#Transactional
public class PersonJpaRepository {
//connects to Databse
#PersistenceContext
EntityManager entityManager;
public Person findById(int id) {
return entityManager.find(Person.class, id);
}
}
I have also data saved in database as:
But when I try to receive the Person object by Id using
logger.info("User id is ",personJpaRepository.findById(2));
I am just getting as :
As Person object needs to print there,but the code is successfully compiling but I am not getting the information regarding the person.My code has no error but it is not retrieving the data.Why is the Person object not printing in the console?

getting error in JPA Entity relationship simple example

I'm doing simple JPA entity relationship many to ine in spring using annotation while i am getting error that "com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'id' cannot be null";
Below is my pojos
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
#Entity
#Table(name = "STUDENTDB")
public class Student {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
private String name;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
And mapped class as given below.
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
#Entity
public class Marks {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long sid;
private int subject1;
private int subject2;
private int subject3;
#ManyToOne(optional=false)
#JoinColumn(name="id",referencedColumnName="id")
private Student s;
public Student getS() {
return s;
}
public void setS(Student s) {
this.s = s;
}
public long getSid() {
return sid;
}
public void setSid(long sid) {
this.sid = sid;
}
public int getSubject1() {
return subject1;
}
public void setSubject1(int subject1) {
this.subject1 = subject1;
}
public int getSubject2() {
return subject2;
}
public void setSubject2(int subject2) {
this.subject2 = subject2;
}
public int getSubject3() {
return subject3;
}
public void setSubject3(int subject3) {
this.subject3 = subject3;
}
}
So what can be possible solution for this?

package com.example;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
#Entity
#Table(name = "STUDENTDB")
public class Student {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(nullable=false,updatable=false)
private long id;
private String name;
}

Please check the following:
The table named STUDENTDB is defined in the database such that the primary key column id has AUTO_INCREMENT attribute.
Without the above attribute #GeneratedValue(strategy = GenerationType.AUTO) is not going to work in the present scenario.

Not able to create oneToMany relationship in Hibernate

I am new to Hibernate and I am trying to understand the oneToMany concept. I have created two entities which are Person and Book. A person can borrow many books and a book can only have one person borrowing it. So I have made the following classes
Person.java
import java.util.Date;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import org.hibernate.annotations.GenericGenerator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
#Entity
#Table(name="PERSON")
public class Person {
private static final Logger _logger = LoggerFactory.getLogger(Person.class);
#Id
#GenericGenerator(name="adder", strategy="increment")
#GeneratedValue(generator="adder")
#Column(name="PID")
private Long id;
#Column(name="FIRSTNAME")
private String firstName;
#Column(name="LASTNAME")
private String lastName;
#Column(name="BIRTHDATE")
#Temporal(TemporalType.DATE)
private Date birthDate;
//add genre and books
#OneToMany(orphanRemoval=true, mappedBy="person", cascade=CascadeType.ALL,targetEntity=Book.class)
private Set<Book> listOfBooks = new HashSet<Book>();
public Set<Book> getListOfBooks() {
return listOfBooks;
}
public void setListOfBooks(Set<Book> listOfBooks) {
this.listOfBooks = listOfBooks;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public Date getBirthDate() {
return birthDate;
}
public void setBirthDate(Date birthDate) {
this.birthDate = birthDate;
}
//add constructor with all the details
}
Book.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
#Entity
#Table(name="BOOK")
public class Book {
private static final Logger logger = LoggerFactory.getLogger(Book.class);
#Id
#GenericGenerator(name="adder", strategy="increment")
#GeneratedValue(generator="adder")
private Long bookId;
#Column(name="NAME")
private String name;
#Column(name="AUTHOR")
private String author;
#Column(name="PUBLICATION_YEAR")
private int yearOfPublication;
#Column(name="PUBLISHER")
private String publisher;
#ManyToOne()
#JoinColumn(name="PERSON_ID")
private Person person;
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
public Long getBookId() {
return bookId;
}
public void setBookId(Long bookId) {
this.bookId = bookId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public int getYearOfPublication() {
return yearOfPublication;
}
public void setYearOfPublication(int yearOfPublication) {
this.yearOfPublication = yearOfPublication;
}
public String getPublisher() {
return publisher;
}
public void setPublisher(String publisher) {
this.publisher = publisher;
}
}
HibernateLibraryDaoMain.java
import java.util.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import se325.project.assignment1.hibernate.domain.Book;
import se325.project.assignment1.hibernate.domain.Person;
public class HibernateLibraryDaoMain {
public static void main(String[] args) {
Person person = new Person();
person.setFirstName("Bob");
person.setLastName("Marley");
person.setBirthDate(new Date());
Book book = new Book();
book.setName("Bob Marley book");
book.setAuthor("Lily Marley");
book.setPublisher("Marley Publications");
book.setYearOfPublication(2000);
Book book1 = new Book();
book1.setName("Laura Marley book");
book1.setAuthor("Laura Marley");
book1.setPublisher("Laura Publications");
book1.setYearOfPublication(2005);
person.getListOfBooks().add(book);
person.getListOfBooks().add(book1);
book.setPerson(person);
book1.setPerson(person);
Configuration configuration = new Configuration();
configuration.configure("se325/project/assignment1/hibernate/hibernate.cfg.xml");
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
session.beginTransaction();
session.save(person);
session.save(book);
session.save(book1);
session.getTransaction().commit();
session.close();
}
}
The problem is that Hibernate does not create a separate Table that illustrates the oneToMany relationship. I can't seem to find the problem. Any help would be appreciated.

I understand where I went wrong. When I have a mappedBy property set, then Hibernate doesn't create a third table but instead it adds to the Entity that has the ManyToOne and joinColumn property. Thanks to all the users that helped :)

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