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How can I reach database as json value when i request on my local browser?

Note: This is a project which has a connection with database on other tables. I just made a new table, but i must have something wrong in my codes, because i cant get what i want.
I have a City table, and this table has 3 columns, named id, name, city_id. And i imported a csv file, so when i query, I can see some data.
I wrote Entity, Repository, Controller, and Service, in Java on Eclipse
What should I do? For example, when i search like localhost:8181/mfc/city/getAllCities that should give me all the cities as json
Could you tell me what i should add?
City.java
package com.mfc.entity;
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="city")
public class City{
#Id
#Column(name="id")
#GeneratedValue(strategy=GenerationType.IDENTITY)
int id;
#Column(name="city_name")
String cityName;
#Column(name="city_id")
int cityId;
public City() {
super();
}
public City(int id, String cityName, int cityId) {
super();
this.id = id;
this.cityName = cityName;
this.cityId = cityId;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public int getCityId() {
return cityId;
}
public void setCityId(int cityId) {
this.cityId = cityId;
}
}
CityController.java
package com.mfc.admin.controller;
import java.util.List;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import com.mfc.admin.service.CityService;
import com.mfc.entity.City;
#RestController
#RequestMapping("/city")
public class CityController {
private static final Logger logger = LogManager.getLogger(CityController.class);
#Autowired
CityService cityService;
#RequestMapping(value="/getAllCities", method=RequestMethod.GET, headers = "Accept=application/json")
public List getCities() {
logger.trace("CityController: getAllCities begins");
List listOfCities = cityService.getAllCities();
logger.trace("CityController: getAllCities ends");
return listOfCities;
}
#RequestMapping(value="/getCity/{id}", method=RequestMethod.GET, headers = "Accept=application/json")
public City getCityById(#PathVariable int id) {
return cityService.getCity(id);
}
}
CityService.java
package com.mfc.admin.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.mfc.entity.City;
import com.mfc.repository.CityRepository;
#Service("cityService")
public class CityService {
#Autowired
CityRepository cityDTO;
#Transactional
public List getAllCities() {
return cityDTO.getAllCities();
}
#Transactional
public City getCity(int id) {
return cityDTO.getCity(id); // getCity is red here, there is mistake i guess
}
}
CityRepository.java
package com.mfc.repository;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import com.mfc.entity.City;
public interface CityRepository extends JpaRepository<City, Integer>{
List getAllCities();
City getCity();
}

In the CityService you call the CityRepository like this
return cityDTO.getCity(id); // getCity is red here, there is mistake i guess
But no such method is defined in the CityRepository. Try using this line return cityDTO.findById(id).get();
You can't see the method findById(Integer id) in the CityRepository, but it is there, because the CityRepository extends JpaRepository<City, Integer>. Find some Spring Data tutorial to know what's really going on in here, long story short the Spring Data is able to generate a lot of standard methods for you.
The method cityDTO.findById(id) returns Optional<City>, not City. To get the instance of City, just add '.get()' method, as it is in the example. It should work for you if city exists in the database. For proper work with Optional find some tutorial. It is a wrapper of an object that may or may not be present, detailed explanation is out of the scope of this answer.

maybe you can try to set up message converter manualy, google MappingJackson2HttpMessageConverter and you'll know what to do.

Spring-Data Project is not receiving my Get/Post "404 not found"

I finished creating a simple Spring-boot project in which I can enter users and through the Get command it returns me the name (from a list of identical names) with the oldest entry date. Unfortunately, every time I ask for Get it returns this ERROR:
D:\>curl -G localhost:8080/demo/first?=Biagio
{"timestamp":"2020-10-04T22:46:35.996+00:00","status":404,"error":"Not Found","message":"","path":"/demo/first"}
And to each of my POST / Add requests like this ERROR:
D:\>curl localhost:8080/demo/add -d name=Giovanni -d email=giovanni#gmail.com -d surname=Jackie
{"timestamp":"2020-10-04T22:40:51.928+00:00","status":404,"error":"Not Found","message":"","path":"/demo/add"}
Below I enter the interested parties of my project to try to get something out of it, because I have been stuck for days now
AccessingDataMysqlApplication.java
package com.example.accessingdatamysql;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;
#SpringBootApplication
public class AccessingDataMysqlApplication {
public static void main(String[] args) {
SpringApplication.run(AccessingDataMysqlApplication.class, args);
}
}
MainController.java
package com.example.accessingdatamysql.rest;
import javax.persistence.NoResultException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.transaction.annotation.Transactional;
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.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import com.example.accessingdatamysql.model.UserDto;
import com.example.accessingdatamysql.service.UserService;
#RestController
#RequestMapping("/demo")
public class MainController {
#Autowired
private UserService userService;
#Transactional
//#RequestMapping(value = "/add/", method = RequestMethod.POST)
#PostMapping(path="/demo/add")
public String addNewUser(#PathVariable("name") String name, #PathVariable("email") String email,
#PathVariable("surname") String surname) {
UserDto n = new UserDto();
n.setName(name);
n.setSurname(surname);
n.setEmail(email);
userService.create(n);
return "User Saved in DB";
}
#SuppressWarnings({ "rawtypes", "unchecked" })
//#RequestMapping(value = "/fetchUser/{name}", method = RequestMethod.GET)
#GetMapping("/demo/first")
public ResponseEntity<UserDto> fetchUser(#PathVariable("name") String name) {
System.out.println(name);
try {
UserDto namefound = userService.findFirstByName(name);
System.out.println("Name found");
ResponseEntity<UserDto> user = new ResponseEntity<UserDto>(namefound, HttpStatus.OK);
return user;
} catch(NoResultException ne) {
System.out.println("User not found");
return new ResponseEntity("User not found with name : " + name, HttpStatus.NOT_FOUND);
}
}
}
UserService.java
package com.example.accessingdatamysql.service;
import org.springframework.stereotype.Service;
import com.example.accessingdatamysql.model.UserDto;
#Service
public interface UserService {
UserDto findFirstByName(String name);
void create(UserDto user);
}
UserServiceImpl.java
package com.example.accessingdatamysql.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;
import com.example.accessingdatamysql.model.UserDto;
import com.example.accessingdatamysql.model.UserEntity;
import com.example.accessingdatamysql.repo.UserRepository;
import com.example.accessingdatamysql.util.UserMapper;
#Service
public class UserServiceImpl implements UserService {
#Autowired
private UserRepository userRepository;
#Autowired
UserMapper mapper;
#Override
public UserDto findFirstByName(String name) {
UserEntity entity = userRepository.findFirstByName(name);
return mapper.toDtoMapper(entity);
}
#Override
public void create(UserDto user) {
UserEntity entity = mapper.toEntityMapper(user);
userRepository.create(entity);
}
}
UserMapper.java
package com.example.accessingdatamysql.util;
import org.mapstruct.Mapper;
import com.example.accessingdatamysql.model.UserDto;
import com.example.accessingdatamysql.model.UserEntity;
#Mapper(componentModel = "spring")
public interface UserMapper {
public UserEntity toEntityMapper (UserDto user);
public UserDto toDtoMapper (UserEntity userEntity);
}
UserRepository.java
package com.example.accessingdatamysql.repo;
import org.springframework.stereotype.Repository;
import com.example.accessingdatamysql.model.UserEntity;
#Repository
public interface UserRepository {
UserEntity findFirstByName(String name);
void create(UserEntity entity);
}
UserRepositoryImpl.java
package com.example.accessingdatamysql.service;
import javax.persistence.EntityManager;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import org.springframework.stereotype.Component;
import com.example.accessingdatamysql.model.UserEntity;
import com.example.accessingdatamysql.repo.UserRepository;
#Component
public class UserRepositoryImpl implements UserRepository {
private final EntityManager em;
public UserRepositoryImpl(EntityManager entityManager) {
this.em = entityManager;
}
#Override
public UserEntity findFirstByName(String name) {
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<UserEntity> criteria = builder.createQuery(UserEntity.class);
Root<UserEntity> root = criteria.from(UserEntity.class);
criteria.select(root).where(builder.equal(root.get("name"), name));
criteria.orderBy(builder.asc(root.get("timestamp")));
TypedQuery<UserEntity> query = em.createQuery(criteria).setMaxResults(1);
return query.getSingleResult();
}
#Override
// per la creazione//
public void create(UserEntity entity) {
em.persist(entity);
}
}
UserDto.java
package com.example.accessingdatamysql.model;
import java.io.Serializable;
import java.sql.Timestamp;
public class UserDto implements Serializable {
/**
*
*/
private static final long serialVersionUID = -7621330660870602403L;
/**
*
*/
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Timestamp getTimestamp() {
return timestamp;
}
public void setTimestamp(Timestamp timestamp) {
this.timestamp = timestamp;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
private Timestamp timestamp;
private String email;
private String surname;
}
If you need I can also insert User.java and the pom, but the pom has no problems as the dependencies are all correct.

You have an additional demo in your path descriptions for GET and POST methods, you should remove it:
#GetMapping("/demo/first")
#PostMapping(path = "/demo/first")
It should be :
#GetMapping("/first")
#PostMapping(path = "/first")
This because you have already defined demo in the RequestMapping annotation in the class level.

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

issue with interface io.javabrains.repository.DepartmentRepository

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>

Insert ID manually for JPA in Spring Boot

How can I insert id manually for this JPA entity in Spring boot? I don't want the id to be autogenerated. I tried sending a POST request using postman sending this JSON object to a RestController:
{
"id":"1",
"name":"New York"
}
I get an error saying that I should manually assing id. Why it is not taking the id that I'm passing in the request?
The Code:
Entity
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
#Entity
public class City{
#Id
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;
}
}
Controller:
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
#RestController
public class CityService{
private CityService cityService;
#Autowired
public void setCityService(CityService CityService) {
this.CityService = CityService;
}
#RequestMapping(method=RequestMethod.POST, value="/cities")
public void cities(#RequestBody City city){
cityService.save(city);
}
}
Service:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.List;
#Service
public class CityService {
private CityRepository cityRepository;
#Autowired
public CityServiceImpl(CityRepository cityRepository) {
this.cityRepository= cityRepository;
}
#Override
public void saveCity(City city) {
CityRepository.save(city);
}
}

Theres probably something wrong with your setters. Try generating them again.

There was an old table with a different structure in the database. There was no error in the code.